AD8314ARM [ADI]

100 MHz-2500 MHz 45 dB RF Detector/Controller; 100兆赫, 2500兆赫45分贝RF检测器/控制器
AD8314ARM
型号: AD8314ARM
厂家: ADI    ADI
描述:

100 MHz-2500 MHz 45 dB RF Detector/Controller
100兆赫, 2500兆赫45分贝RF检测器/控制器

电信集成电路 电信电路 光电二极管 控制器
文件: 总16页 (文件大小:277K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
100 MHz–2500 MHz 45 dB  
RF Detector/Controller  
a
AD8314  
FEATURES  
For convenience, the signal is internally ac-coupled, using a 5 pF  
capacitor to a load of 3 kin shunt with 2 pF. This high-pass  
coupling, with a corner at 16 MHz, determines the lowest oper-  
ating frequency. Thus, the source may be dc-grounded.  
Complete RF Detector/Controller Function  
Typical Range –58 dBV to –13 dBV  
–45 dBm to 0 dBm re 50  
Frequency Response from 100 MHz to 2.5 GHz  
Temperature-Stable Linear-in-dB Response  
Accurate to 2.5 GHz  
Rapid Response: 70 ns to a 10 dB Step  
Low Power: 12 mW at 2.7 V  
The AD8314 provides two voltage outputs. The first, called  
V_UP, increases from close to ground to about 1.2 V as the  
input signal level increases from 1.25 mV to 224 mV. This output  
is intended for use in measurement mode. Consult the Appli-  
cations section of this data sheet for information on use in this  
mode. A capacitor may be connected between the V_UP and  
FLTR pins when it is desirable to increase the time interval over  
which averaging of the input waveform occurs.  
Power-Down to 20 A  
APPLICATIONS  
Cellular Handsets (TDMA, CDMA, GSM)  
RSSI and TSSI for Wireless Terminal Devices  
Transmitter Power Measurement and Control  
The second output, V_DN, is an inversion of V_UP, but with  
twice the slope and offset by a fixed amount. This output starts  
at about 2.25 V (provided the supply voltage is 3.3 V) for  
the minimum input and falls to a value close to ground at the  
maximum input. This output is intended for analog control  
loop applications. A setpoint voltage is applied to VSET and  
V_DN is then used to control a VGA or power amplifier. Here  
again, an external filter capacitor may be added to extend the  
averaging time. Consult the Applications section of this data  
sheet for information on use in this mode.  
PRODUCT DESCRIPTION  
The AD8314 is a complete low-cost subsystem for the mea-  
surement and control of RF signals in the frequency range  
0.1 GHz–2.5 GHz, with a typical dynamic range of 45 dB,  
intended for use in a wide variety of cellular handsets and other  
wireless devices. It provides a wider dynamic range and better  
accuracy than possible using discrete diode detectors. In particular,  
its temperature stability is excellent over the full operating range of  
–30°C to +85°C.  
The AD8314 is available in a micro_SOIC package and con-  
sumes 4.5 mA from a 2.7 V to 5.5 V supply. When powered  
down, the typical sleep current is 20 µA.  
Its high sensitivity allows control at low power levels, thus  
reducing the amount of power that needs to be coupled to the  
detector. It is essentially a voltage-responding device, with a  
typical signal range of 1.25 mV to 224 mV rms or –58 dBV to  
–13 dBV. This is equivalent to –45 dBm to 0 dBm re 50 .  
FUNCTIONAL BLOCK DIAGRAM  
FLTR  
V-I  
VSET  
V UP  
I-V  
DET  
DET  
DET  
DET  
DET  
X2  
V DN  
RFIN  
10dB  
10dB  
10dB  
10dB  
VPOS  
ENBL  
BAND-GAP  
REFERENCE  
OFFSET  
COMP'N  
AD8314  
COMM  
(PADDLE)  
REV. 0  
Information furnished by Analog Devices is believed to be accurate and  
reliable. However, no responsibility is assumed by Analog Devices for its  
use, nor for any infringements of patents or other rights of third parties  
which may result from its use. No license is granted by implication or  
otherwise under any patent or patent rights of Analog Devices.  
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.  
Tel: 781/329-4700  
Fax: 781/326-8703  
World Wide Web Site: http://www.analog.com  
© Analog Devices, Inc., 1999  
(V = 3 V, T = +25؇C, unless otherwise noted)  
AD8314–SPECIFICATIONS  
S
A
Parameter  
Condition  
Min  
Typ  
Max  
Unit  
OVERALL FUNCTION  
Frequency Range  
Input Voltage Range  
Equivalent Power Range  
Logarithmic Slope  
Logarithmic Intercept  
Equivalent dBm Level  
To Meet All Specifications  
Internally AC-Coupled  
52.3 External Termination  
Main Output, V_UP, 100 MHz1  
Main Output, V_UP, 100 MHz  
52.3 External Termination  
0.1  
1.25  
–45  
18.85  
–68  
–55  
2.5  
224  
0
23.35  
–56  
–43  
GHz  
mV rms  
dBm  
mV/dB  
dBV  
dBm  
21.3  
–62  
–49  
INPUT INTERFACE  
DC Resistance to COMM  
Inband Input Resistance  
Input Capacitance  
(Pin RFIN)  
100  
3
2
kΩ  
kΩ  
pF  
f = 0.1 GHz  
f = 0.1 GHz  
MAIN OUTPUT  
Voltage Range  
Minimum Output Voltage  
Maximum Output Voltage2  
General Limit  
Available Output Current  
Response Time  
(Pin V_UP)  
V_UP Connected to VSET  
No Signal at RFIN, RL 10 kΩ  
RL 10 kΩ  
2.7 V VS 5.5 V  
Sourcing/Sinking  
10%–90%, 10 dB Step  
f = 0.1 GHz (Worst Condition)  
0.01  
0.01  
1.9  
VS – 1.1  
1/0.5  
1.2  
0.05  
V
V
V
V
mA  
ns  
µV  
0.02  
2
VS – 1  
2/1  
70  
100  
Residual RF (at 2f)  
INVERTED OUTPUT  
Gain Referred to V_UP  
Minimum Output Voltage  
Maximum Output Voltage  
Available Output Current  
Output-Referred Noise  
Response Time  
(Pin V_DN)  
V
DN = 2.25 V – 2 × VUP  
–2  
0.05  
2.2  
6/200  
1.05  
70  
VS 3.3 V  
0.01  
2.1  
4/100  
0.1  
2.5  
V
V
VS 3.3 V3  
Sourcing/Sinking  
mA/µA  
µV/Hz  
ns  
RF Input = 2 GHz, –33 dBV, fNOISE = 10 kHz  
10%–90%, 10 dB Input Step  
–40 dBm to 0 dBm Input Step, to 95%  
Full-Scale Settling Time  
150  
ns  
SETPOINT INPUT  
Voltage Range  
Input Resistance  
(Pin VSET)  
Corresponding to Central 40 dB  
0.15  
7
1.2  
V
kΩ  
10  
Logarithmic Scale Factor  
f = 0.900 GHz  
f = 1.900 GHz  
20.7  
19.7  
mV/dB  
mV/dB  
ENABLE INTERFACE  
Logic Level to Enable Power  
Input Current when HI  
(Pin ENBL)  
HI Condition, –30°C TA +85°C  
2.7 V at ENBL, –30°C TA +85°C  
LO Condition, –30°C TA +85°C  
1.6  
VPOS  
300  
0.8  
V
µA  
V
20  
Logic Level to Disable Power  
–0.5  
POWER INTERFACE  
Supply Voltage  
Quiescent Current  
Over Temperature  
Total Supply Current when Disabled  
Over Temperature  
(Pin VPOS)  
2.7  
3.0  
2.7  
3.0  
4.5  
4.4  
20  
5.5  
5.7  
6.6  
95  
V
mA  
mA  
µA  
µA  
–30°C TA +85°C  
–30°C TA +85°C  
40  
NOTES  
1Mean and Standard Deviation specifications are available in Table I.  
2Increased output possible when using an attenuator between V_UP and VSET to raise the slope.  
3Refer to Figure 19 for details.  
Specifications subject to change without notice.  
REV. 0  
–2–  
AD8314  
Pin Function Descriptions  
ABSOLUTE MAXIMUM RATINGS*  
Supply Voltage VPOS . . . . . . . . . . . . . . . . . . . . . . . . . . .5.5 V  
V_UP, V_DN, VSET, ENBL . . . . . . . . . . . . . . . . 0 V, VPOS  
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 V rms  
Equivalent Power . . . . . . . . . . . . . . . . . . . . . . . . . . . +17 dBm  
Internal Power Dissipation . . . . . . . . . . . . . . . . . . . . 200 mW  
θJA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200°C  
Maximum Junction Temperature . . . . . . . . . . . . . . . . . 125°C  
Operating Temperature Range . . . . . . . . . . . –30°C to +85°C  
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C  
Lead Temperature Range (Soldering 60 sec) . . . . . . . . . 300°C  
Pin  
Name  
Function  
1
2
RFIN  
ENBL  
RF Input.  
Connect pin to VS for normal operation.  
Connect pin to ground for disable mode.  
Setpoint input for operation in controller  
mode. To operate in detector mode connect  
VSET to V_UP  
Connection for an external capacitor to slow  
the response of the output. Capacitor is con-  
nected between FLTR and V_UP.  
3
4
VSET  
FLTR  
*Stresses above those listed under Absolute Maximum Ratings may cause permanent  
damage to the device. This is a stress rating only; functional operation of the device  
at these or any other conditions above those indicated in the operational section  
of this specification is not implied. Exposure to absolute maximum rating conditions  
for extended periods may affect device reliability.  
5
6
COMM Device Common (Ground).  
V_UP  
V_DN  
VPOS  
Logarithmic output. Output voltage increases  
with increasing input amplitude.  
Inversion of V_UP, governed by the following  
equation: V_DN = 2.25 V – 2 × VUP  
7
8
.
PIN CONFIGURATION  
Positive supply voltage (VS), 2.7 V to 5.5 V.  
1
2
3
4
8
7
6
5
VPOS  
V DN  
RFIN  
ENBL  
VSET  
FLTR  
AD8314  
TOP VIEW  
(Not to Scale)  
V UP  
COMM  
ORDERING GUIDE  
Model  
Temperature Range  
Package Description  
Package Option  
AD8314ARM*  
–30°C to +85°C  
Tube, 8-Lead micro_SOIC  
13" Tape and Reel  
7" Tape and Reel  
RM-8  
AD8314ARM-REEL  
AD8314ARM-REEL7  
AD8314-EVAL  
Evaluation Board  
*Device branded as J5A.  
CAUTION  
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily  
accumulate on the human body and test equipment and can discharge without detection. Although  
the AD8314 features proprietary ESD protection circuitry, permanent damage may occur on  
devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are  
recommended to avoid performance degradation or loss of functionality.  
WARNING!  
ESD SENSITIVE DEVICE  
REV. 0  
–3–  
AD8314–Typical Performance Characteristics  
4
3
2
1.2  
0.1GHz  
1.0  
2.5GHz  
0.1GHz  
1.9GHz  
0.9GHz  
0.8  
1
0
1.9GHz  
0.6  
2.5GHz  
–1  
–2  
0.9GHz  
0.4  
0.2  
0
–3  
–4  
–70  
–60  
–50  
–40  
–30  
–20  
–10  
0
–75  
–65  
–55  
–45  
–35  
–25  
–15  
–5  
(–52dBm)  
(–47dBm)  
(+3dBm)  
INPUT AMPLITUDE – dBV  
(–2dBm)  
INPUT AMPLITUDE – dBV  
Figure 4. Log Conformance vs. Input Amplitude  
Figure 1. VUP vs. Input Amplitude  
3
1.2  
1.0  
0.8  
0.6  
0.4  
0.2  
3
1.2  
2
2
1.0  
0.8  
0.6  
0.4  
0.2  
+25؇C  
+85؇C  
1
1
–30؇C  
+85؇C  
–30؇C  
+25؇C  
–30؇C  
0
0
+25؇C  
–1  
–2  
–3  
–1  
–2  
–3  
SLOPE AND INTERCEPT  
NORMALIZED AT +25؇C AND  
APPLIED TO –30؇C AND +85؇C  
SLOPE AND INTERCEPT  
NORMALIZED AT +25؇C AND  
APPLIED TO –30؇C AND +85؇C  
0
0
–70  
–60  
(–47dBm)  
–50  
–40  
–30  
–20  
–10  
(+3dBm)  
0
–60  
(–47dBm)  
–10  
(+3dBm)  
–70  
–50  
–40  
–30  
–20  
0
INPUT AMPLITUDE – dBV  
INPUT AMPLITUDE – dBV  
Figure 5. VUP and Log Conformance vs. Input Amplitude  
Figure 2. VUP and Log Conformance vs. Input Amplitude at  
at 1.9 GHz; –30°C, +25°C, and +85°C  
0.1 GHz; –30°C, +25°C, and +85°C  
3
3
1.2  
1.2  
2
2
1.0  
1.0  
+25؇C  
+85؇C  
1
1
0.8  
0.6  
0.4  
0.2  
0
0.8  
0.6  
0.4  
0.2  
0
+85؇C  
+85؇C  
+25؇C  
–30؇C  
0
0
–30؇C  
–1  
–2  
–3  
–1  
–2  
–3  
SLOPE AND INTERCEPT  
NORMALIZED AT +25؇C AND  
APPLIED TO –30؇C AND +85؇C  
SLOPE AND INTERCEPT  
NORMALIZED AT +25؇C AND  
APPLIED TO –30؇C AND +85؇C  
–60  
(–47dBm)  
–10  
(+3dBm)  
–70  
–60  
(–47dBm)  
–50  
–40  
–30  
–20  
–10  
(+3dBm)  
0
–70  
–50  
–40  
–30  
–20  
0
INPUT AMPLITUDE – dBV  
INPUT AMPLITUDE – dBV  
Figure 6. VUP and Log Conformance vs. Input Amplitude  
Figure 3. VUP and Log Conformance vs. Input Amplitude  
at 2.5 GHz; –30°C, +25°C, and +85°C  
at 0.9 GHz; –30°C, +25°C, and +85°C  
REV. 0  
–4–  
AD8314  
23  
–55  
–60  
–65  
22  
21  
20  
–30؇C  
–30؇C  
+25؇C  
+25؇C  
+85؇C  
+85؇C  
–70  
–75  
19  
18  
0.5  
1.0  
1.5  
2.0  
2.5  
0
0.5  
1.0  
1.5  
2.0  
2.5  
0
FREQUENCY – GHz  
FREQUENCY – GHz  
Figure 7. Slope vs. Frequency; –30°C, +25°C, and +85°C  
Figure 10. VUP Intercept vs. Frequency: –30°C, +25°C, and  
+85°C  
22  
–61  
0.1GHz  
–62  
0.1GHz  
2.5GHz  
21  
–63  
0.9GHz  
0.9GHz  
–64  
–65  
20  
1.9GHz  
–66  
2.5GHz  
1.9GHz  
5.0  
19  
2.5  
–67  
2.5  
3.0  
3.5  
4.0  
4.5  
5.0  
5.5  
3.0  
3.5  
4.0  
4.5  
5.5  
V
– Volts  
V
– Volts  
S
S
Figure 8. VUP Slope vs. Supply Voltage  
Figure 11. VUP Intercept vs. Supply Voltage  
3500  
3000  
2500  
2000  
0
6
5
4
X
–200  
–400  
–600  
–800  
FREQUENCY (GHz)  
R || - jX⍀  
3030 || - j748⍀  
760 || - j106⍀  
301 || - j80⍀  
90 || - j141⍀  
0.1  
0.9  
1.9  
2.5  
DECREASING  
3
2
V
ENBL  
INCREASING  
1500  
1000  
V
ENBL  
X
R
1
–1000  
–1200  
–1400  
R
500  
0
0
–1  
0.5  
1.0  
1.5  
2.0  
2.5  
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6  
FREQUENCY – GHz  
V
– Volts  
ENBL  
Figure 9. Input Impedance  
Figure 12. Supply Current vs. ENBL Voltage, VS = 3 V  
REV. 0  
–5–  
AD8314  
AVERAGE: 128 SAMPLES  
AVERAGE: 128 SAMPLES  
500mV/VERT. DIV.  
V
DN  
V
1V/VERT. DIV.  
DN  
V
UP 500mV/  
V
GND  
DN  
VERT. DIV.  
GND  
GND  
1s PER  
HORIZONTAL  
DIVISION  
PULSED RF  
0.1GHz, –13dBV  
V
UP 500mV/VERT. DIV.  
RF INPUT  
100ns PER  
HORIZONTAL  
DIVISION  
200mV PER  
VERTICAL  
DIVISION  
V
GND  
GND  
V
UP  
ENBL  
5V PER VERTICAL DIVISION  
V
ENBL  
Figure 13. ENBL Response Time  
Figure 16. VUP and VDN Response Time, –40 dBm to 0 dBm  
HP8648B  
EXT TRIG  
OUT  
10MHz REF OUTPUT  
PULSE MODE IN  
TRIG  
OUT  
PICOSECOND  
PULSE LABS  
PULSE  
TRIG  
OUT  
SIGNAL  
GENERATOR  
PULSE  
MODULATION  
MODE  
HP8648B  
SIGNAL  
GENERATOR  
HP8116A  
PULSE  
GENERATOR  
10MHz REF OUTPUT  
EXT TRIG  
GENERATOR  
–33dBV RF OUT  
PULSE OUT  
RF OUT  
–3dB  
RF  
TEK P6204  
3.0V  
0.1F  
SPLITTER  
FET PROBE  
3.0V  
0.1F  
–3dB  
VPOS  
V DN  
8
7
6
5
1
2
3
4
RFIN  
TRIG  
VPOS  
V DN  
8
7
1
2
3
4
RFIN  
TRIG  
TEK P6204  
FET PROBE  
52.3⍀  
ENBL  
52.3⍀  
TEK  
TDS784C  
SCOPE  
TEK P6204  
FET PROBE  
3.0V  
ENBL  
VSET  
FLTR  
AD8314  
TEK  
TEK P6204  
FET PROBE  
TDS784C  
SCOPE  
AD8314  
V UP  
VSET  
FLTR  
TEK P6204  
FET PROBE  
V UP  
6
5
COMM  
NC  
COMM  
NC  
NC = NO CONNECT  
NC = NO CONNECT  
Figure 14. Test Setup for ENBL Response Time  
Figure 17. Test Setup for Pulse Response  
0
80  
10.0  
–10  
–20  
–30  
–40  
–50  
–60  
–70  
–80  
–90  
–100  
–110  
RF INPUT  
–70dBm  
75  
70  
65  
60  
55  
50  
45  
40  
35  
30  
25  
–60dBm  
–50dBm  
–30dBm  
–40dBm  
–20dBm  
1.0  
–120  
–130  
–140  
–150  
–160  
–170  
20  
15  
10  
5
0
–5  
10  
0.1  
100  
100  
1k  
10k  
100k  
1M  
10M  
1k  
10k  
100k  
1M  
10M  
FREQUENCY – Hz  
FREQUENCY – Hz  
Figure 15. AC Response from VSET to V_DN  
Figure 18. VDN Noise Spectral Density  
REV. 0  
–6–  
AD8314  
2.3  
2.2  
2.1  
2.0  
2.3  
2.2  
2.1  
2.0  
1.9  
1.8  
1.7  
0mA  
2mA  
SHADING INDICATES  
؎3 SIGMA  
4mA  
6mA  
1.9  
1.8  
1.7  
2.8  
2.9  
3.0  
3.1  
3.2  
3.3  
3.4  
3.5  
2.7  
2.8  
2.9  
3.0  
3.1  
3.2  
3.3  
3.4  
3.5  
2.7  
V
– Volts  
V
– Volts  
S
S
Figure 19. Maximum VDN Voltage vs. VS by Load Current  
Figure 22. Maximum VDN Voltage vs. VS with 3 mA Load  
AVERAGE: 128 SAMPLES  
AVERAGE: 128 SAMPLES  
V
UP  
200mV PER  
VERTICAL  
DIVISION  
500mV/VERT. DIV.  
V
DN  
V
DN  
V
GND  
GND  
V
GND  
GND  
DN  
DN  
500mV/VERT. DIV.  
V
UP  
V
UP  
VPOS AND ENABLE  
2V PER  
VERTICAL  
DIVISION  
100ns PER  
HORIZONTAL  
DIVISION  
2V PER  
VERTICAL  
DIVISION  
VPOS AND ENABLE  
1s PER  
HORIZONTAL  
DIVISION  
GND  
Figure 20. Power-On and -Off Response, Measurement  
Mode  
Figure 23. Power-On Response, VDN, Controller Mode with  
VSET Held Low  
TRIG  
OUT  
TRIG  
OUT  
HP8648B  
SIGNAL  
GENERATOR  
HP8648B  
SIGNAL  
GENERATOR  
EXT TRIG  
HP8116A  
PULSE  
GENERATOR  
10MHz REF OUTPUT  
HP8112A  
PULSE  
GENERATOR  
EXT TRIG  
10MHz REF OUTPUT  
PULSE  
OUT  
RF OUT  
–33dBV  
PULSE  
OUT  
RF OUT  
AD811  
49.9⍀  
AD811  
49.9⍀  
732⍀  
TRIG  
RFIN  
ENBL  
VSET  
FLTR  
VPOS  
V DN  
8
7
6
5
1
2
3
4
RFIN  
ENBL  
VSET  
FLTR  
8
7
6
5
1
2
3
4
VPOS  
732⍀  
TRIG  
TEK  
TDS784C  
SCOPE  
52.3⍀  
52.3⍀  
TEK  
TDS784C  
SCOPE  
TEK P6204  
FET PROBE  
TEK P6204  
FET PROBE  
V DN  
V UP  
AD8314  
AD8314  
TEK P6204  
FET PROBE  
V UP  
+0.2  
NC  
COMM  
NC  
COMM  
NC  
NC = NO CONNECT  
NC = NO CONNECT  
Figure 21. Test Setup for Power-On and -Off Response  
Figure 24. Test Setup for Power-On Response at V_DN  
Output, Controller Mode with VSET Pin Held Low  
REV. 0  
–7–  
AD8314  
Table I. Typical Specifications at Selected Frequencies at 25؇C (Mean and Sigma)  
؎1 dB Dynamic Range* – dBV  
High Point Low Point  
Slope – mV/dB  
Intercept – dBV  
Frequency – GHz  
0.1  
0.9  
1.9  
2.5  
21.3  
20.7  
19.7  
19.2  
0.4  
0.4  
0.4  
0.4  
–62.2  
–63.6  
–66.3  
–62.1  
0.4  
0.4  
0.4  
0.7  
–11.8  
–13.8  
–19  
0.3  
0.3  
0.7  
1.7  
–59  
–61.4  
–64  
0.5  
0.4  
0.6  
1.3  
–16.4  
–61  
*Refer to Figure 29.  
GENERAL DESCRIPTION  
However, in using this part, it must be understood that log amps  
do not fundamentally respond to power. It is for this reason that  
we use dBV (decibels above 1 V rms) rather than the commonly  
used metric of dBm. While the dBV scaling is fixed, independent  
of termination impedance, the corresponding power level is not.  
For example, 224 mV rms is always –13 dBV (with one further  
condition of an assumed sinusoidal waveform; see the Applications  
section for more information about the effect of waveform on  
logarithmic intercept), and it corresponds to a power of 0 dBm  
when the net impedance at the input is 50 . When this imped-  
ance is altered to 200 , the same voltage clearly represents a  
power level that is four times smaller (P = V2/R), that is, –6 dBm.  
Note that dBV may be converted to dBm for the special case of a  
50 system by simply adding 13 dB (0 dBV is equivalent to  
+13 dBm).  
The AD8314 is a logarithmic amplifier (log amp) similar in  
design to the AD8313; further details about the structure and  
function may be found in the AD8313 data sheet and other log  
amps produced by Analog Devices. Figure 25 shows the main  
features of the AD8314 in block schematic form.  
The AD8314 combines two key functions needed for the mea-  
surement of signal level over a moderately wide dynamic range.  
First, it provides the amplification needed to respond to small  
signals, in a chain of four amplifier/limiter cells, each having  
a small-signal gain of 10 dB and a bandwidth of approximately  
3.5 GHz. At the output of each of these amplifier stages is a  
full-wave rectifier, essentially a square-law detector cell, that  
converts the RF signal voltages to a fluctuating current having  
an average value that increases with signal level. A further passive  
detector stage is added ahead of the first stage. Thus, there are  
five detectors, each separated by 10 dB, spanning some 50 dB  
of dynamic range. The overall accuracy at the extremes of this  
total range, viewed as the deviation from an ideal logarithmic  
response, that is, the law-conformance error, can be judged by  
reference to Figure 4, which shows that errors across the central  
40 dB are moderate. Other curves show how the conformance  
to an ideal logarithmic function varies with supply voltage,  
temperature and frequency.  
Thus, the external termination added ahead of the AD8314  
determines the effective power scaling. This will often take the  
form of a simple resistor (52.3 will provide a net 50 input)  
but more elaborate matching networks may be used. This im-  
pedance determines the logarithmic intercept, the input power  
for which the output would cross the baseline (V_UP = zero) if  
the function were continuous for all values of input. Since this is  
never the case for a practical log amp, the intercept refers to  
the value obtained by the minimum-error straight-line fit to the  
actual graph of V_UP versus PIN (more generally, VIN). Again,  
keep in mind that the quoted values assume a sinusoidal (CW)  
signal. Where there is complex modulation, as in CDMA, the  
calibration of the power response needs to be adjusted accordingly.  
Where a true power (waveform-independent) response is needed,  
the use of an rms-responding detector, such as the AD8361,  
should be considered.  
The output of these detector cells is in the form of a differential  
current, making their summation a simple matter. It can easily  
be shown that such summation closely approximates a logarith-  
mic function. This result is then converted to a voltage, at pin  
V_UP, through a high-gain stage. In measurement modes, this  
output is connected back to a voltage-to-current (V–I) stage, in  
such a manner that V_UP is a logarithmic measure of the RF input  
voltage, with a slope and intercept controlled by the design. For  
a fixed termination resistance at the input of the AD8314, a given  
voltage corresponds to a certain power level.  
However, the logarithmic slope, the amount by which the output  
V_UP changes for each decibel of input change (voltage or  
power) is, in principle, independent of waveform or termination  
impedance. In practice, it usually falls off somewhat at higher  
FLTR  
V-I  
VSET  
V UP  
I-V  
DET  
DET  
DET  
DET  
DET  
X2  
V DN  
RFIN  
10dB  
10dB  
10dB  
10dB  
VPOS  
ENBL  
BAND-GAP  
REFERENCE  
OFFSET  
COMP'N  
AD8314  
COMM  
(PADDLE)  
Figure 25. Block Schematic  
–8–  
REV. 0  
AD8314  
frequencies, due to the declining gain of the amplifier stages and  
other effects in the detector cells. For the AD8314, the slope  
at low frequencies is nominally 21.3 mV/dB, falling almost linearly  
with frequency to about 19.2 mV/dB at 2.5 GHz. These values  
are sensibly independent of temperature (see Figure 7) and  
almost totally unaffected by the supply voltage from 2.7 V to  
5.5 V (Figure 8).  
APPLICATIONS  
Basic Connections  
Figure 28 shows connections for the basic measurement mode.  
A supply voltage of 2.7 V to 5.5 V is required. The supply to  
the VPOS pin should be decoupled with a low inductance 0.1 µF  
surface mount ceramic capacitor. A series resistor of about 10 Ω  
may be added; this resistor will slightly reduce the supply voltage to  
the AD8314 (maximum current into the VPOS pin is approxi-  
mately 9 mA when V_DN is delivering 5 mA). Its use should be  
avoided in applications where the power supply voltage is very  
low (i.e., 2.7 V). A series inductor will provide similar power  
supply filtering with minimal drop in supply voltage.  
Inverted Output  
The second provision is the inclusion of an inverting amplifier  
to the output, for use in controller applications. Most power  
amplifiers require a gain-control bias that must decrease from a  
large positive value toward ground level as the power output is  
required to decrease. This control voltage, which appears at the pin  
V_DN, is not only of the opposite polarity to V_UP, but also  
needs to have an offset added in order to determine its most posi-  
tive value when the power level (assumed to be monitored through  
a directional coupler at the output of the PA) is minimal.  
0.1F  
52.3⍀  
RFIN  
ENBL  
VSET  
FLTR  
VPOS  
V DN  
8
7
6
5
V
V
INPUT  
1
2
3
4
S
OPTIONAL  
(SEE TEXT)  
V
S
DN  
AD8314  
The starting value of V_DN is nominally 2.25 V, and it falls  
on a slope of twice that of V_UP, in other words, –43 mV/dB.  
Figure 26 shows how this is achieved: the reference voltage  
that determines the maximum output is derived from the on-  
chip voltage reference, and is substantially independent of the  
supply voltage or temperature. However, the full output cannot  
be attained for supply voltages under 3.3 V; Figure 19 shows  
this dependency. The relationship between V_UP and V_DN is  
shown in Figure 27.  
V UP  
V
UP  
COMM  
C
F
OPTIONAL  
(SEE TEXT)  
Figure 28. Basic Connections for Operation in  
Measurement Mode  
The ENBL pin is here connected to VPOS. The AD8313 may  
be disabled by pulling this pin to ground when the chip current  
is reduced to about 20 µA from its normal value of 4.5 mA.  
The logic threshold is around +VS/2 and the enable function  
occurs in about 1.5 µs. Note, however, further settling time is  
generally needed at low input levels.  
V_UP  
CURRENTS FROM  
+2  
I–V  
V_DN  
DETECTORS  
VSET  
V–I  
V
= 2.25V – 2.0 
؋
 V_UP  
DN  
AD8314  
FLTR  
The AD8314 has an internal input coupling capacitor. This  
eliminates the need for external ac-coupling. A broadband input  
match is achieved in this example by connecting a 52.3 resis-  
tor between RFIN and ground. This resistance combines with  
the internal input impedance of approximately 3 kto give  
an overall broadband input resistance of 50 . Several other  
coupling methods are possible; these are described in the Input  
Coupling section.  
BAND-GAP  
REFERENCE  
1.125V  
Figure 26. Output Interfaces  
2.5  
2.0  
1.5  
1.0  
0.5  
OUTPUT FOR  
PA CONTROL  
The measurement mode is selected by connecting VSET to V_UP,  
which establishes a feedback path and sets the logarithmic slope  
to its nominal value. The peak voltage range of the measurement  
extends from –58 dBV to –13 dBV at 0.9 GHz, and only slightly  
less at higher frequencies up to 2.5 GHz. Thus, using the 50 Ω  
termination, the equivalent power range is –45 dBm to 0 dBm.  
At a slope of 21.5 mV/dB, this would amount to an output span  
of 967 mV. Figure 29 shows the transfer function for V_UP at a  
supply voltage of 3 V, and input frequency of 0.9 GHz.  
V_DN  
V_UP  
OUTPUT FOR  
MEASUREMENT  
V_DN, which will generally not be used when the AD8314 is  
used in the measurement mode, is essentially an inverted version  
of V_UP. The voltage on V_UP and V_DN are related by the  
equation.  
0
–60  
–50  
–40  
–30  
–20  
–10  
0
INPUT AMPLITUDE – dBV  
Figure 27. Showing V_UP and V_DN Relationship  
V
DN = 2.25 V – 2 VUP  
While V_DN can deliver up to 6 mA, the load resistance on V_UP  
should not be lower than 10 kin order that the full-scale output  
of 1 V can be generated with the limited available current of  
200 µA max. Figure 29 shows the logarithmic conformance  
under the same conditions.  
REV. 0  
–9–  
AD8314  
Filter Capacitor  
3
1.2  
1.0  
0.8  
0.6  
0.4  
0.2  
V
= 3V  
S
The video bandwidth of both V_UP and V_DN is approximately  
3.5 MHz. In CW applications where the input frequency is much  
higher than this, no further filtering of the demodulated signal  
will be required. Where there is a low-frequency modulation of  
the carrier amplitude, however, the low-pass corner must be  
reduced by the addition of an external filter capacitor, CF (see  
Figure 28). The video bandwidth is related to CF by the equation  
R
= 52.3⍀  
T
2
؎1dB DYNAMIC RANGE  
1
0
1
Video Bandwidth =  
–1  
–2  
–3  
2 π × 4.4 kΩ × (10 pF + CF )  
Operating in Controller Mode  
؎3dB DYNAMIC RANGE  
INTERCEPT  
–50 –40  
INPUT AMPLITUDE – dBV  
Figure 30 shows the basic connections for operation in the con-  
troller mode and Figure 31 shows a block diagram of a typical  
controller mode application. The feedback from V_UP to VSET is  
broken and the desired setpoint voltage is applied to VSET from  
the controlling source (often this will be a DAC). VDN will rail  
high (2.2 V on a 3.3 V supply, 1.9 V on a 2.7 V supply) when  
the applied power is less than the value corresponding to the set-  
point voltage. When the input power slightly exceeds this value,  
VDN would, in the absence of the loop via the power amplifier  
gain pin, decrease rapidly toward ground. In the closed loop,  
however, the reduction in VDN causes the power amplifier to re-  
duce its output. This restores a balance between the actual power  
level sensed at the input of the AD8314 and the demanded value  
determined by the setpoint. This assumes that the gain control  
sense of the variable gain element is positive, that is, an increas-  
ing voltage from V_DN will tend to increase gain. The output  
swing and current sourcing capability of V_DN are shown in  
Figures 19 and 20.  
0
–70  
–60  
(–47dBm)  
–30  
–20  
–10  
(+3dBm)  
0
Figure 29. VUP and Log Conformance Error vs. Input  
Level vs. Input Level at 900 MHz  
Transfer Function in Terms of Slope and Intercept  
The transfer function of the AD8314 is characterized in terms of  
its Slope and Intercept. The logarithmic slope is defined as the  
change in the RSSI output voltage for a 1 dB change at the input.  
For the AD8314, slope is nominally 21.5 mV/dB. So a 10 dB  
change at the input results in a change at the output of approxi-  
mately 215 mV. The plot of Log-Conformance (Figure 29) shows  
the range over which the device maintains its constant slope. The  
dynamic range can be defined as the range over which the error  
remains within a certain band, usually ±1 dB or ±3 dB. In  
Figure 29, for example, the ±1 dB dynamic range is approxi-  
mately 50 dB (from –13 dBV to –63 dBV).  
The intercept is the point at which the extrapolated linear  
response would intersect the horizontal axis (Figure 29). Using  
the slope and intercept, the output voltage can be calculated for  
any input level within the specified input range using the equation:  
0.1F  
52.3⍀  
V
RFIN  
8
7
6
5
INPUT  
VSET  
1
2
3
4
VPOS  
V DN  
S
VUP = VSLOPE × (PIN – PO)  
V
VDN  
ENBL  
S
AD8314  
where VUP is the demodulated and filtered RSSI output, VSLOPE  
is the logarithmic slope, expressed in V/dB, PIN is the input sig-  
nal, expressed in decibels relative to some reference level (either  
dBm or dBV in this case) and PO is the logarithmic intercept,  
expressed in decibels relative to the same reference level.  
V UP  
VSET  
FLTR  
COMM  
C
F
For example, at an input level of –40 dBV (–27 dBm), the  
output voltage will be  
Figure 30. Basic Connections for Operation in Controller  
Mode  
V
OUT = 0.020 V/dB × (–40 dBV – (–63 dBV )) = 0.46 V  
dBV vs. dBm  
POWER  
The most widely used convention in RF systems is to specify power  
in dBm, that is, decibels above 1 mW in 50 . Specification of  
log amp input levels in terms of power is strictly a concession to  
popular convention; they do not respond to power (tacitly “power  
absorbed at the input”), but to the input voltage. The use of dBV,  
defined as decibels with respect to a 1 V rms sine wave, is more pre-  
cise, although this is still not unambiguous because waveform is  
also involved in the response of a log amp, which, for a complex  
input (such as a CDMA signal), will not follow the rms value  
exactly. Since most users specify RF signals in terms of power—  
more specifically, in dBm/50 —we use both dBV and dBm in  
specifying the performance of the AD8314, showing equivalent  
dBm levels for the special case of a 50 environment. Values in  
dBV are converted to dBm re 50 by adding 13.  
AMPLIFIER  
RF INPUT  
DIRECTIONAL  
COUPLER  
GAIN  
C
F
CONTROL  
VOLTAGE  
V UP V DN  
VSET  
DAC  
FLTR  
AD8314  
RFIN  
52.3⍀  
Figure 31. Typical Controller Mode Application  
REV. 0  
–10–  
AD8314  
The relationship between the input level and the setpoint voltage  
follows from the nominal transfer function of the device (VUP vs.  
Input Amplitude, see Figure 1). For example, a voltage of 1 V  
on VSET is demanding a power level of 0 dBm at RFIN. The cor-  
responding power level at the output of the power amplifier will be  
greater than this amount due to the attenuation through the direc-  
tional coupler.  
the large input resistance. For low frequencies, Option a or  
Option c (see below) are recommended.  
In Figure 32b, the matching components are drawn as general  
reactances. Depending on the frequency, the input impedance at  
that frequency and the availability of standard value components,  
either a capacitor or an inductor will be used. As in the previous  
case, the input impedance at a particular frequency is plotted on  
a Smith Chart and matching components are chosen (shunt  
or series L, shunt or series C) to move the impedance to the  
center of the chart. Table II gives standard component values  
for some popular frequencies. Matching components for other  
frequencies can be calculated using the input resistance and  
reactance data over frequency which is given in Figure 9. Note  
that the reactance is plotted as though it appears in parallel with  
the input impedance (which it does because the reactance is prima-  
rily due to input capacitance).  
When connected in a PA control loop, as shown in Figure 31,  
the voltage VUP is not explicitly used, but is implicated in again  
setting up the required averaging time, by choice of CF. However,  
now the effective loop response time is a much more complicated  
function of the PA’s gain-control characteristics, which are very  
nonlinear. A complete solution requires specific knowledge of  
the power amplifier.  
The transient response of this control loop is determined by the  
filter capacitor, CF. When this is large, the loop will be uncon-  
ditionally stable (by virtue of the “dominant pole” generated  
by this capacitor), but the response will be sluggish. The minimum  
value ensuring stability should be used, requiring full attention  
to the particulars of the power amplifier control function. Because  
this is invariably nonlinear, the choice must be made for the  
worst-case condition, which usually corresponds to the smallest  
output from the PA, where the gain function is steepest. In practice,  
an improvement in loop dynamics can often be achieved by adding  
a response zero, formed by a resistor in series with CF.  
The impedance matching characteristics of a reactive matching  
network provide voltage gain ahead of the AD8314; this increases  
the device sensitivity (see Table II). The voltage gain is calculated  
using the equation:  
R2  
Voltage GaindB = 20 log10  
R1  
where R2 is the input impedance of the AD8314 and R1 is the  
source impedance to which the AD8314 is being matched. Note  
that this gain will only be achieved for a perfect match. Component  
tolerances and the use of standard values will tend to reduce  
the gain.  
Power-On and Enable Glitch  
As already mentioned, the AD8314 can be put into a low power  
mode by pulling the ENBL pin to ground. This reduces the quies-  
cent current from 4.5 mA to 20 µA. Alternatively, the supply can  
be turned off completely to eliminate the quiescent current. Figures  
13 and 23 show the behavior of the V_DN output under these  
two conditions (in Figure 23, ENBL is tied to VPOS). The glitch  
that results in both cases can be reduced by loading the V_DN  
output.  
50SOURCE  
50⍀  
AD8314  
RFIN  
C
C
R
52.3⍀  
SHUNT  
R
C
IN  
IN  
V
BIAS  
Input Coupling Options  
The internal 5 pF coupling capacitor of the AD8314, along with  
the low frequency input impedance of 2 kgive a high-pass input  
corner frequency of approximately 16 MHz. This sets the mini-  
mum operating frequency. Figure 32 shows three options for  
input coupling. A broadband resistive match can be implemented  
by connecting a shunt resistor to ground at RFIN (Figure 32a).  
This 52.3 resistor (other values can also be used to select dif-  
ferent overall input impedances) resistor combines with the  
input impedance of the AD8314 (3 kʈ2 pF) to give a broad-  
band input impedance of 50 . While the input resistance and  
capacitance (CIN and RIN) will vary by approximately ± 20% from  
device to device, the dominance of the external shunt resistor  
means that the variation in the overall input impedance will  
be close to the tolerance of the external resistor.  
a. Broadband Resistive  
50SOURCE  
AD8314  
X1  
50⍀  
RFIN  
C
C
C
R
X2  
IN  
IN  
V
BIAS  
b. Narrowband Reactive  
AD8314  
RFIN  
R
C
ATTN  
C
STRIPLINE  
R
C
IN  
IN  
At frequencies above 2 GHz, the input impedance drops below  
250 (see Figure 9), so it is appropriate to use a larger value of  
shunt resistor. This value is calculated by plotting the input  
impedance (resistance and capacitance) on a Smith Chart and  
choosing the best value of shunt resistor to bring the input imped-  
ance closest to the center of the chart. At 2.5 GHz, a shunt  
resistor of 165 is recommended.  
V
BIAS  
c. Series Attenuation  
Figure 32. Input Coupling Options  
Figure 32c shows a third method for coupling the input signal  
into the AD8314, applicable in applications where the input signal  
is larger than the input range of the log amp. A series resistor,  
connected to the RF source, combines with the input impedance  
A reactive match can also be implemented as shown in Figure  
32b. This is not recommended at low frequencies as device toler-  
ances will dramatically vary the quality of the match because of  
REV. 0  
–11–  
AD8314  
of the AD8314 to resistively divide the input signal being applied  
to the input. This has the advantage of very little power being  
“tapped off” in RF power transmission applications.  
Table III. Shift in AD8314 Output for Signals with Differing  
Crest Factors  
Correction Factor  
(Add to Measured  
Table II. Recommended Components for X1 and X2 in  
Figure 32b  
Signal Type  
Input Level)  
Sine Wave  
Square Wave  
GSM Channel (All Time Slots On)  
CDMA Channel (Forward Link,  
9 Channels On)  
CDMA Channel (Reverse Link)  
PDC Channel (All Time Slots On)  
0 dB  
Frequency  
(GHz)  
Voltage Gain  
(dB)  
–3.01 dB  
0.55 dB  
3.55 dB  
X1  
X2  
0.1  
0.9  
1.9  
2.5  
Short  
52.3 Ω  
39 nH  
15 nH  
3.9 nH  
33 nH  
10 nH  
1.5 pF  
11.8  
7.8  
2.55  
0.5 dB  
0.58 dB  
Increasing the Logarithmic Slope in Measurement Mode  
The nominal logarithmic slope of 21.5 mV/dB (see Figure 7 for  
the variation of slope with frequency) can be increased to an  
arbitrarily high value by attenuating the signal between V_UP  
and VSET as shown in Figure 33. The ratio R1/R2 is set using  
the equation  
Mobile Handset Power Control Examples  
Figure 34 shows a complete power amplifier control circuit for  
a dual mode handset. This circuit is applicable to any dual  
mode handset using TDMA or CDMA technologies. The  
PF08107B (Hitachi) is driven by a nominal power level of  
+3 dBm. Some of the output power from the PA is coupled off  
using an LDC15D190A0007A (Murata) directional coupler.  
This has a coupling factor of approximately 19 dB for its lower  
frequency band (897.5 ± 17.5 MHz) and 14 dB for its upper band  
(1747.5 ± 37.5 MHz) and an insertion loss of 0.38 dB and 0.45 dB  
respectively. Because the PF08107B transmits a maximum power  
level of +35 dBm, additional attenuation of 15 dB is required  
before the coupled signal is applied to the AD8314.  
R1/R2 = (New Slope/Original Slope) – 1  
In the example shown, two 5 kresistors combine to change the  
slope at 1900 MHz from 20 mV/dB to 40 mV/dB. The slope can  
be increased to higher levels. This will, however, reduce the usable  
dynamic range of the device.  
40mV/dB  
V_UP  
@ 1900MHz  
3.5V  
R1  
5k⍀  
VSET  
R2  
4.7F  
5k⍀  
AD8314  
1000pF  
BAND  
SELECT  
0V/2V  
Figure 33. Increasing the Output Slope  
POUT BAND 1  
+35dBm MAX  
Effect of Waveform Type on Intercept  
TO  
ANTENNA  
LDC15D190A0007A  
PIN BAND 1  
+3dBm  
V
Although specified for input levels in dBm (dB relative to 1 mW),  
the AD8314 fundamentally responds to voltage and not to power.  
A direct consequence of this characteristic is that input signals of  
equal rms power but differing crest factors will produce different  
results at the log amp’s output.  
CTL  
7
8
5
1
4
3
PF081807B  
(HITACHI)  
49.9⍀  
PIN BAND 2  
+3dBm  
V
2
6
APC  
POUT BAND 2  
+32dBm MAX  
ATTN  
15dB  
52.3⍀  
The effect of differing signal waveforms is to shift the effective  
value of the intercept upwards or downwards. Graphically, this  
looks like a vertical shift in the log amp’s transfer function. The  
logarithmic slope, however, is not affected. For example, consider  
the case of the AD8314 being alternately fed by an unmodulated  
sine wave and by a single CDMA channel of the same rms power.  
The AD8314’s output voltage will differ by the equivalent of  
3.55 dB (70 mV) over the complete dynamic range of the device  
(the output for a CDMA input being lower).  
0.1F  
0dBm  
MAX  
+V  
2.7V  
S
RFIN  
8
1
2
3
4
VPOS  
V DN  
+V  
S
ENBL  
7
AD8314  
VSET  
0V–1.1V  
V UP  
6
5
VSET  
FLTR  
COMM  
Table III shows the correction factors that should be applied to  
measure the rms signal strength of a various signal types. A  
sine wave input is used as a reference. To measure the rms power  
of a square wave, for example, the mV equivalent of the dB value  
given in the table (20 mV/dB times 3.01 dB) should be subtracted  
from the output voltage of the AD8314.  
C
F
220pF  
Figure 34. A Dual Mode Power Amplifier Control Circuit  
REV. 0  
–12–  
AD8314  
3.5V  
The setpoint voltage, in the range 0 V to 1.1 V, is applied to the  
VSET pin of the AD8314. This will typically be supplied by a  
Digital-to-Analog Converter (DAC). This voltage is compared  
to the input level to the AD8314. Any imbalance is between VSET  
and the RF input level is corrected by V_DN, which drives the  
VAPC (gain control) of the power amplifier. V_DN reaches a  
maximum value of approximately 1.9 V on a 2.7 V supply (this  
will be higher for higher supply voltages) while delivering approxi-  
mately 3 mA to the VAPC input.  
47F  
2.2F  
680pF  
TO  
ANTENNA  
+35dBm  
MAX  
DC09-73  
RF INPUT  
A filter capacitor (CF) must be used to stabilize the loop. The  
choice of CF will depend to a large degree on the gain control  
dynamics of the power amplifier, something that is frequently  
poorly characterized, so some trial and error may be necessary.  
In this example, a 220 pF capacitor gives the loop sufficient  
speed to follow the GSM and DCS1800 time slot ramping profiles,  
while still having a stable, critically-damped response.  
6
4
P
IN  
0dBm  
BGY241  
3
5
+15dBm  
1
2
ATTN  
15dB  
52.3⍀  
0.1F  
0dBm  
MAX  
V
S
RFIN  
ENBL  
VSET  
FLTR  
VPOS  
Figure 35 shows the relationship between the setpoint voltage,  
2.7V  
V
SET and output power, at 0.9 GHz. The overall gain control  
V
S
V DN  
V UP  
function is linear in dB for a dynamic range of over 40 dB.  
AD8314  
V
SET  
Figure 36 shows a similar circuit for a single band handset power  
amplifier. The BGY241 (Phillips) is driven by a nominal power  
level of 0 dBm. A 20 dB directional coupler, DC09-73 (Alpha) is  
used to couple the signal in this case. Figure 37 shows the rela-  
tionship between the control voltage and the output power at  
0.9 GHz.  
0V–1.1V  
COMM  
C
F
220pF  
In both of these examples, noise on the V_DN pin can be reduced  
by placing a simple RC low-pass filter between VDN and the gain  
control pin of the power amplifier. However, the value of the  
resistor should be kept low to minimize the voltage drop across  
it due to the dc current flowing into the gain control input.  
Figure 36. A Single Mode Power Amplifier Control Circuit  
40  
30  
20  
10  
40  
30  
20  
10  
0
0
–10  
–20  
–30  
–40  
–50  
–10  
0
0.2  
0.4  
0.6  
0.8  
1.0  
VSET – Volts  
–20  
–30  
Figure 37. POUT vs. VSET at 0.9 GHz for Single Mode  
Handset  
0
0.2  
0.4  
0.6  
0.8  
1.0  
1.2  
VSET – Volts  
Figure 35. POUT vs. VSET at 0.9 GHz for Dual Mode  
Handset Power Amplifier Application  
REV. 0  
–13–  
AD8314  
by a single 0.1 µF capacitor. Additional decoupling, in the form  
of a series resistor or inductor in R9, can also be added. Table IV  
details the various configuration options of the evaluation board.  
EVALUATION BOARD  
Figure 38 shows the schematic of the AD8314 evaluation board.  
The layout and silkscreen of the component side are shown in  
Figures 39 and 40. The board is powered by a single supply  
in the range, 2.7 V to 5.5 V. The power supply is decoupled  
C1  
0.1F  
R2  
52.3⍀  
R9  
0⍀  
V
R1  
0⍀  
RFIN  
VPOS  
V DN  
8
7
6
5
INPUT  
VSET  
1
2
3
4
POS  
R3  
0⍀  
VPOS  
SW1  
V DN  
ENBL  
VSET  
FLTR  
R4  
C2  
AD8314  
(OPEN)  
(OPEN)  
V UP  
R5  
0⍀  
COMM  
LK1  
V UP  
C4  
(OPEN)  
R6  
(OPEN)  
C3  
(OPEN)  
R8  
(OPEN)  
R7  
0⍀  
Figure 38. Evaluation Board Schematic  
Figure 39. Layout of Component Side  
Figure 40. Silkscreen of Component Side  
REV. 0  
–14–  
AD8314  
Table IV. Evaluation Boards Configuration Options  
Component  
Function  
Default Condition  
TP1, TP2  
SW1  
Supply and Ground Vector Pins  
Not Applicable  
SW1 = A  
Device Enable: When in position A, the ENBL  
pin is connected to +VS and the AD8314 is in  
operating mode. In Position B, the ENBL pin is  
grounded, putting the device in power-down mode.  
R1, R2  
Input Interface: The 52.3 resistor in position  
R2 combines with the AD8314’s internal input  
impedance to give a broadband input impedance  
of around 50 . A reactive match can be imple-  
mented by replacing R2 with an inductor and  
R1 (0 ) with a capacitor. Note that the AD8314’s  
RF input is internally ac-coupled.  
R2 = 52.3 (Size 0603)  
R1 = 0 (Size 0402)  
R3, R4, C2, R5, R6, C3  
Output Interface: R4, C2, R6, and C3 can be  
used to check the response of V_UP and V_DN  
to capacitive and resistive loading. R3/R4 and  
R5/R6 can be used to reduce the slope of V_UP  
and V_DN.  
R4 = C2 = R6 = C3 = Open (Size 0603)  
R3 = R5 = 0 (Size 0603)  
C1, R9  
Power Supply Decoupling: The nominal supply  
decoupling consists of a 0.1 µF capacitor (C1). A  
series inductor or small resistor can be placed in  
R9 for additional decoupling.  
C1 = 0.1 µF (Size 0603)  
R9 = 0 (Size 0603)  
C4  
Filter Capacitor: The response time of V_UP  
and V_DN can be modified by placing a capacitor  
between FLTR (pin 4) and V_UP.  
C4 = Open (Size 0603)  
R7, R8  
LK1  
Slope Adjust: By installing resistors in R7 and R8,  
the nominal slope of 20 mV/dB can be increased.  
See Slope Adjust discussion for more details.  
Measurement/Controller Mode: LK1 shorts  
V_UP to VSET, placing the AD8314 in  
measurement mode. Removing LK1 places  
the AD8314 in controller mode.  
R7 = 0 (Size 0603)  
R8 = Open (Size 0603)  
LK1 = Installed  
REV. 0  
–15–  
AD8314  
OUTLINE DIMENSIONS  
Dimensions shown in inches and (mm).  
8-Lead micro_SOIC  
(RM-8)  
0.122 (3.10)  
0.114 (2.90)  
8
5
4
0.122 (3.10)  
0.114 (2.90)  
0.199 (5.05)  
0.187 (4.75)  
1
PIN 1  
0.0256 (0.65) BSC  
0.120 (3.05)  
0.112 (2.84)  
0.120 (3.05)  
0.112 (2.84)  
0.043 (1.09)  
0.037 (0.94)  
0.006 (0.15)  
0.002 (0.05)  
33؇  
27؇  
0.018 (0.46)  
0.008 (0.20)  
0.028 (0.71)  
0.016 (0.41)  
0.011 (0.28)  
0.003 (0.08)  
SEATING  
PLANE  
–16–  
REV. 0  

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