NE614A [NXP]

Low power FM IF system; 低功率调频中频系统
NE614A
型号: NE614A
厂家: NXP    NXP
描述:

Low power FM IF system
低功率调频中频系统

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中文:  中文翻译
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RF COMMUNICATIONS PRODUCTS  
SA614A  
Low power FM IF system  
Product specification  
Replaces data of December 15, 1994  
1997 Nov 07  
IC17 Data Handbook  
Philip s Se m ic ond uc tors  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
DESCRIPTION  
PIN CONFIGURATION  
The SA614A is an improved monolithic low-power FM IF system  
incorporating two limiting intermediate frequency amplifiers,  
quadrature detector, muting, logarithmic received signal strength  
indicator, and voltage regulator. The SA614A features higher IF  
bandwidth (25MHz) and temperature compensated RSSI and  
limiters permitting higher performance application compared with the  
SA604. The SA614A is available in a 16-lead dual-in-line plastic  
and 16-lead SO (surface-mounted miniature) package.  
D and N Packages  
1
2
3
4
5
6
7
8
16  
15  
IF AMP DECOUPLING  
GND  
IF AMP INPUT  
IF AMP DECOUPLING  
14 IF AMP OUTPUT  
MUTE INPUT  
13  
V
GND  
CC  
RSSI OUTPUT  
12 LIMITER INPUT  
11  
10  
9
MUTE AUDIO OUTPUT  
LIMITER DECOUPLING  
LIMITER DECOUPLING  
FEATURES  
UNMUTE AUDIO OUTPUT  
QUADRATURE INPUT  
Low power consumption: 3.3mA typical  
LIMITER  
Temperature compensated logarithmic Received Signal Strength  
SR00323  
Indicator (RSSI) with a dynamic range in excess of 90dB  
Figure 1. Pin Configuration  
Two audio outputs - muted and unmuted  
Low external component count; suitable for crystal/ceramic filters  
APPLICATIONS  
Cellular radio FM IF  
Excellent sensitivity: 1.5µV across input pins (0.22µV into 50Ω  
matching network) for 12dB SINAD (Signal to Noise and Distortion  
ratio) at 455kHz  
High performance communications receivers  
Intermediate frequency amplification and detection up to 25MHz  
RF level meter  
SA614A meets cellular radio specifications  
Spectrum analyzer  
Instrumentation  
FSK and ASK data receivers  
ORDERING INFORMATION  
DESCRIPTION  
TEMPERATURE RANGE  
-40 to +85°C  
ORDER CODE  
SA614AN  
DWG #  
SOT38-4  
SOT109-1  
16-Pin Plastic Dual In-Line Package (DIP)  
16-Pin Plastic Small Outline (SO) package (Surface-mount)  
-40 to +85°C  
SA614AD  
2
1997 Nov 07  
853-0594 18663  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
BLOCK DIAGRAM  
16  
15  
14  
13  
12  
11  
10  
9
GND  
IF  
AMP  
LIMITER  
LIMITER  
QUAD  
DET  
SIGNAL  
STRENGTH  
VOLTAGE  
REGULATOR  
MUTE  
V
GND  
CC  
1
2
3
4
5
6
7
8
SR00324  
Figure 2. Block Diagram  
ABSOLUTE MAXIMUM RATINGS  
SYMBOL  
PARAMETER  
RATING  
UNITS  
V
Single supply voltage  
Storage temperature range  
Operating ambient temperature range SA614A  
9
V
CC  
°C  
°C  
T
STG  
-65 to +150  
-40 to +85  
T
A
°C/W  
°C/W  
Thermal impedance  
D package  
N package  
90  
75  
θ
JA  
DC ELECTRICAL CHARACTERISTICS  
V
CC  
= +6V, T = 25°C; unless otherwise stated.  
A
LIMITS  
SA614A  
TYP  
SYMBOL  
PARAMETER  
TEST CONDITIONS  
UNITS  
MIN  
4.5  
MAX  
V
CC  
Power supply voltage range  
DC current drain  
8.0  
4.0  
V
I
2.5  
3.3  
mA  
CC  
Mute switch input threshold (ON)  
(OFF)  
V
V
1.7  
1.0  
3
1997 Nov 07  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
AC ELECTRICAL CHARACTERISTICS  
Typical reading at T = 25°C; V = +6V, unless otherwise stated. IF frequency = 455kHz; IF level = -47dBm; FM modulation = 1kHz with  
A
CC  
+8kHz peak deviation. Audio output with C-message weighted filter and de-emphasis capacitor. Test circuit Figure 3. The parameters listed  
below are tested using automatic test equipment to assure consistent electrical characterristics. The limits do not represent the ultimate  
performance limits of the device. Use of an optimized RF layout will improve many of the listed parameters.  
LIMITS  
SYMBOL  
PARAMETER  
TEST CONDITIONS  
SA614A  
TYP  
-92  
UNITS  
MIN  
MAX  
Input limiting -3dB  
Test at Pin 16  
dBm/50Ω  
AM rejection  
80% AM 1kHz  
25  
60  
33  
dB  
Recovered audio level  
Recovered audio level  
Total harmonic distortion  
Signal-to-noise ratio  
15nF de-emphasis  
150pF de-emphasis  
175  
530  
-42  
260  
mV  
mV  
RMS  
RMS  
THD  
S/N  
-30  
dB  
No modulation for noise  
RF level = -118dBm  
RF level = -68dBm  
RF level = -18dBm  
68  
dB  
mV  
V
0
160  
2.50  
4.80  
80  
800  
3.3  
5.8  
1
RSSI output  
1.7  
3.6  
V
RSSI range  
R = 100k (Pin 5)  
4
dB  
dB  
kΩ  
kΩ  
kΩ  
kΩ  
kΩ  
RSSI accuracy  
R = 100k (Pin 5)  
4
+2.0  
1.6  
IF input impedance  
1.4  
0.85  
1.4  
IF output impedance  
Limiter input impedance  
Unmuted audio output resistance  
Muted audio output resistance  
1.0  
1.6  
58  
58  
NOTE:  
1. SA614A data sheets refer to power at 50input termination; about 21dB less power actually enters the internal 1.5k input.  
SA614A (50)  
-97dBm  
-47dBm  
SA614A (1.5k)/SA615 (1.5k)  
-118dBm  
-68dBm  
-18dBm  
+3dBm  
The SA615 and SA614A are both derived from the same basic die. The SA615 performance plots are directly applicable to the SA614A.  
4
1997 Nov 07  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
F
1
NE614A TEST CIRCUIT  
C
4
Q = 20 LOADED  
C
R
1
C
2
2
C
C
5
6
R
3
INPUT  
F
2
R
1
16  
15  
14  
13  
12  
11  
10  
9
8
C
7
SA614A  
C
3
1
2
3
4
5
6
7
C
8
C
9
S
C
1
10  
R
4
C
AUDIO  
OUTPUT  
DATA  
OUTPUT  
12  
C
11  
RSSI  
OUTPUT  
MUTE  
INPUT  
C1 100nF + 80 – 20% 63V K10000–25V Ceramic  
SIGNETICS  
NE614 TEST CKT  
100nF +10% 50V  
100nF +10% 50V  
C2  
C3  
100nF +10% 50V  
C4  
100nF +10% 50V  
C5  
C6  
10pF +2% 100V NPO Ceramic  
100nF +10% 50V  
C7  
100nF +10% 50V  
C8  
15nF +10% 50V  
C9  
150pF +2% 100V N1500 Ceramic  
1nF +10% 100V K2000-Y5P Ceramic  
C10  
C11  
6.8µF +20% 25V Tantalum  
C12  
F1 455kHz Ceramic Filter Murata SFG455A3  
455kHz (Ce = 180pF) TOKO RMC 2A6597H  
F2  
R1  
51+1% 1/4W Metal Film  
1500+1% 1/4W Metal Film  
R2  
1500+5% 1/8W Carbon Composition  
100k+1% 1/4W Metal Film  
R3  
R4  
SIGNETICS  
NE614 TEST CKT  
SR00325  
Figure 3. SA614A Test Circuit  
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1997 Nov 07  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
16  
15  
14  
13  
12  
11  
10  
9
GND  
42k  
42k  
700  
7k  
1.6k  
1.6k  
40k  
40k  
700  
35k  
2k 8k  
4.5k  
2k  
FULL  
WAVE  
RECT.  
FULL  
WAVE  
RECT.  
VOLTAGE/  
CURRENT  
CONVERTER  
V
EE  
MUTE  
QUAD  
VOLT  
REG  
VOLT  
REG  
V
CC  
DET  
40k  
BAND  
GAP  
VOLT  
40k  
V
CC  
55k  
80k  
80k  
55k  
80k  
3
V
GND  
2
CC  
1
4
5
6
7
8
SR00326  
Figure 4. Equivalent Circuit  
6
1997 Nov 07  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
0.5  
to  
SFG455A3  
1.3µH  
22pF  
1nF  
0.1µF  
NE604A TEST CIRCUIT  
0.1µF  
455kHz  
Q=20  
44.545  
3rd OVERTURE  
XTAL  
5.5µH  
5.6pF  
0.1µF  
SFG455A3  
10pF  
+6V  
16  
15  
14  
13  
12  
11  
10  
9
8
8
1
7
6
5
4
100nF  
10nF  
6.8µF  
0.1µF  
SA604A  
SA602  
2
0.1µF  
3
1
2
3
4
5
6
7
47pF  
22pF  
0.1µF  
DATA  
OUT  
0.21  
100k  
to  
0.28µH  
+6V  
C–MSG  
FILTER  
AUDIO  
OUT  
MUTE  
100nF  
RSSI  
614A IF INPUT (µV) (1500)  
10  
100  
1k  
10k  
100k  
AUDIO  
–0  
4V  
3V  
2V  
1V  
RSSI (VOLTS)  
–20  
–40  
–60  
THD + NOISE  
AM (80% MOD)  
NOISE  
–80  
–120  
–100  
–80  
–60  
–40  
–20  
602 RF INPUT (dBm) (50)  
SR00327  
Figure 5. Typical Application Cellular Radio (45MHz to 455kHz)  
small signal AC bandwidth of 28MHz. The outputs of the final  
differential stage are buffered to the internal quadrature detector.  
One of the outputs is available at Pin 9 to drive an external  
quadrature capacitor and L/C quadrature tank.  
CIRCUIT DESCRIPTION  
The SA614A is a very high gain, high frequency device. Correct  
operation is not possible if good RF layout and gain stage practices  
are not used. The SA614A cannot be evaluated independent of  
circuit, components, and board layout. A physical layout which  
correlates to the electrical limits is shown in Figure 3. This  
configuration can be used as the basis for production layout.  
Both of the limiting amplifier stages are DC biased using feedback.  
The buffered output of the final differential amplifier is fed back to the  
input through 42kresistors. As shown in Figure 4, the input  
impedance is established for each stage by tapping one of the  
feedback resistors 1.6kfrom the input. This requires one  
additional decoupling capacitor from the tap point to ground.  
The SA614A is an IF signal processing system suitable for IF  
frequencies as high as 21.4MHz. The device consists of two limiting  
amplifiers, quadrature detector, direct audio output, muted audio  
output, and signal strength indicator (with log output characteristic).  
The sub-systems are shown in Figure 4. A typical application with  
45MHz input and 455kHz IF is shown in Figure 5.  
42k  
V+  
15  
16  
700  
14  
IF Amplifiers  
7k  
1.6k  
The IF amplifier section consists of two log-limiting stages. The first  
consists of two differential amplifiers with 39dB of gain and a small  
signal bandwidth of 41MHz (when driven from a 50source). The  
output of the first limiter is a low impedance emitter follower with  
1kof equivalent series resistance. The second limiting stage  
consists of three differential amplifiers with a gain of 62dB and a  
1
40k  
SR00328  
Figure 6. First Limiter Bias  
7
1997 Nov 07  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
42k  
9
11  
12  
V+  
40k  
BPF  
8
BPF  
10  
40k  
80k  
SR00329  
SR00330  
Figure 7. Second Limiter and Quadrature Detector  
Figure 8. Feedback Paths  
HIGH IMPEDANCE  
BPF  
HIGH IMPEDANCE  
BPF  
LOW IMPEDANCE  
a. Terminating High Impedance Filters with Transformation to Low Impedance  
BPF  
BPF  
A
RESISTIVE LOSS INTO BPF  
b. Low Impedance Termination and Gain Reduction  
Figure 9. Practical Termination  
SR00331  
430  
11  
16  
15  
14  
13  
12  
10  
9
8
614A  
430  
1
2
3
4
5
6
7
SR00332  
Figure 10. Crystal Input Filter with Ceramic Interstage Filter  
Because of the very high gain, bandwidth and input impedance of  
the limiters, there is a very real potential for instability at IF  
frequencies above 455kHz. The basic phenomenon is shown in  
Figure 8. Distributed feedback (capacitance, inductance and  
radiated fields) forms a divider from the output of the limiters back to  
the inputs (including RF input). If this feedback divider does not  
cause attenuation greater than the gain of the forward path, then  
oscillation or low level regeneration is likely. If regeneration occurs,  
two symptoms may be present: (1)The RSSI output will be high with  
no signal input (should nominally be 250mV or lower), and (2) the  
demodulated output will demonstrate a threshold. Above a certain  
8
1997 Nov 07  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
input level, the limited signal will begin to dominate the regeneration,  
and the demodulator will begin to operate in a “normal” manner.  
quadrature tank and the filters. Most filters demonstrate a large  
phase shift across their passband (especially at the edges). If the  
quadrature detector is tuned to the edge of the filter passband, the  
combined filter and quadrature phase shift can aggravate stability.  
This is not usually a problem, but should be kept in mind.  
There are three primary ways to deal with regeneration: (1)  
Minimize the feedback by gain stage isolation, (2) lower the stage  
input impedances, thus increasing the feedback attenuation factor,  
and (3) reduce the gain. Gain reduction can effectively be  
accomplished by adding attenuation between stages. This can also  
lower the input impedance if well planned. Examples of  
impedance/gain adjustment are shown in Figure 9. Reduced gain  
will result in reduced limiting sensitivity.  
Quadrature Detector  
Figure 7 shows an equivalent circuit of the SA614A quadrature  
detector. It is a multiplier cell similar to a mixer stage. Instead of  
mixing two different frequencies, it mixes two signals of common  
frequency but different phase. Internal to the device, a constant  
amplitude (limited) signal is differentially applied to the lower port of  
the multiplier. The same signal is applied single-ended to an  
A feature of the SA614A IF amplifiers, which is not specified, is low  
phase shift. The SA614A is fabricated with a 10GHz process with  
very small collector capacitance. It is advantageous in some  
applications that the phase shift changes only a few degrees over a  
wide range of signal input amplitudes.  
external capacitor at Pin 9. There is a 90° phase shift across the  
plates of this capacitor, with the phase shifted signal applied to the  
upper port of the multiplier at Pin 8. A quadrature tank (parallel L/C  
network) permits frequency selective phase shifting at the IF  
frequency. This quadrature tank must be returned to ground through  
a DC blocking capacitor.  
Stability Considerations  
The high gain and bandwidth of the SA614A in combination with its  
very low currents permit circuit implementation with superior  
performance. However, stability must be maintained and, to do that,  
every possible feedback mechanism must be addressed. These  
mechanisms are: 1) Supply lines and ground, 2) stray layout  
inductances and capacitances, 3) radiated fields, and 4) phase shift.  
As the system IF increases, so must the attention to fields and  
strays. However, ground and supply loops cannot be overlooked,  
especially at lower frequencies. Even at 455kHz, using the test  
layout in Figure 3, instability will occur if the supply line is not  
decoupled with two high quality RF capacitors, a 0.1µF monolithic  
The loaded Q of the quadrature tank impacts three fundamental  
aspects of the detector: Distortion, maximum modulated peak  
deviation, and audio output amplitude. Typical quadrature curves  
are illustrated in Figure 12. The phase angle translates to a shift in  
the multiplier output voltage.  
Thus a small deviation gives a large output with a high Q tank.  
However, as the deviation from resonance increases, the  
non-linearity of the curve increases (distortion), and, with too much  
deviation, the signal will be outside the quadrature region (limiting  
the peak deviation which can be demodulated). If the same peak  
deviation is applied to a lower Q tank, the deviation will remain in a  
region of the curve which is more linear (less distortion), but creates  
a smaller phase angle (smaller output amplitude). Thus the Q of the  
quadrature tank must be tailored to the design. Basic equations and  
an example for determining Q are shown below. This explanation  
includes first-order effects only.  
right at the V pin, and a 6.8µF tantalum on the supply line. An  
CC  
electrolytic is not an adequate substitute. At 10.7MHz, a 1µF  
tantalum has proven acceptable with this layout. Every layout must  
be evaluated on its own merit, but don’t underestimate the  
importance of good supply bypass.  
At 455kHz, if the layout of Figure 3 or one substantially similar is  
used, it is possible to directly connect ceramic filters to the input and  
between limiter stages with no special consideration. At frequencies  
above 2MHz, some input impedance reduction is usually necessary.  
Figure 9 demonstrates a practical means.  
Frequency Discriminator Design Equations for  
SA614A  
V
OUT  
As illustrated in Figure 10, 430external resistors are applied in  
parallel to the internal 1.6kload resistors, thus presenting  
approximately 330to the filters. The input filter is a crystal type for  
narrowband selectivity. The filter is terminated with a tank which  
transforms to 330. The interstage filter is a ceramic type which  
doesn’t contribute to system selectivity, but does suppress wideband  
noise and stray signal pickup. In wideband 10.7MHz IFs the input  
filter can also be ceramic, directly connected to Pin 16.  
SR00333  
Figure 11.  
In some products it may be impractical to utilize shielding, but this  
mechanism may be appropriate to 10.7MHz and 21.4MHz IF. One  
of the benefits of low current is lower radiated field strength, but  
lower does not mean non-existent. A spectrum analyzer with an  
active probe will clearly show IF energy with the probe held in the  
proximity of the second limiter output or quadrature coil. No specific  
recommendations are provided, but mechanical shielding should be  
considered if layout, bypass, and input impedance reduction do not  
solve a stubborn instability.  
(1a)  
C
S
1
+
V
IN  
V
O
=
C
+ C  
S
ω
ω
1
2
P
1
1 +  
1
( )  
Q S  
S
1
(1b)  
(1c)  
where ω =  
1
L(C + C )  
P
S
Q = R (C + C ) ω  
1
1
P
S
The final stability consideration is phase shift. The phase shift of the  
limiters is very low, but there is phase shift contribution from the  
9
1997 Nov 07  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
From the above equation, the phase shift between nodes 1 and 2, or  
A more exact analysis including the source resistance of the  
the phase across C will be:  
previous stage shows that there is a series and a parallel resonance  
in the phase detector tank. To make the parallel and series  
resonances close, and to get maximum attenuation of higher  
S
ω
(2)  
1
Q ω  
1
-1  
φ =  
V
O
-
V =  
t
IN  
g
harmonics at 455kHz IF, we have found that a C = 10pF and C  
=
S
P
ω
2
1
164pF (commercial values of 150pF or 180pF may be practical), will  
give the best results. A variable inductor which can be adjusted  
around 0.7mH should be chosen and optimized for minimum  
( ω )  
1
Figure 12 is the plot of φ vs. (ωω )  
distortion. (For 10.7MHz, a value of C = 1pF is recommended.)  
S
1
It is notable that at ω = ω , the phase shift is  
1
Audio Outputs  
Two audio outputs are provided. Both are PNP current-to-voltage  
π
and the response is close to a straight  
2
∆φ  
converters with 55knominal internal loads. The unmuted output  
is always active to permit the use of signaling tones in systems such  
as cellular radio. The other output can be muted with 70dB typical  
2Q  
ω1  
1
=
line with a slope of  
∆ω  
The signal V would have a phase shift of  
O
attenuation. The two outputs have an internal 180° phase  
difference.  
2Q  
ω1  
π
2
1
ω
with respect to the V  
.
IN  
The nominal frequency response of the audio outputs is 300kHz.  
this response can be increased with the addition of external  
resistors from the output pins to ground in parallel with the internal  
55k resistors, thus lowering the output time constant. Singe the  
output structure is a current-to-voltage converter (current is driven  
into the resistance, creating a voltage drop), adding external parallel  
resistance also has the effect of lowering the output audio amplitude  
and DC level.  
(3)  
(4)  
If V = A Sin ωt  
V = A  
O
IN  
2Q  
π
1
ωt +  
ω
Sin  
ω1  
2
Multiplying the two signals in the mixer, and  
low pass filtering yields:  
2
V
IN V = A Sin ωt  
O
2Q  
ω1  
π
ωt +  
1
ω
This technique of audio bandwidth expansion can be effective in  
many applications such as SCA receivers and data transceivers.  
Sin  
2
after low pass filtering  
1
Because the two outputs have a 180° phase relationship, FSK  
demodulation can be accomplished by applying the two output  
differentially across the inputs of an op amp or comparator. Once  
the threshold of the reference frequency (or “no-signal” condition)  
has been established, the two outputs will shift in opposite directions  
(higher or lower output voltage) as the input frequency shifts. The  
output of the comparator will be logic output. The choice of op amp  
or comparator will depend on the data rate. With high IF frequency  
(10MHz and above), and wide IF bandwidth (L/C filters) data rates in  
excess of 4Mbaud are possible.  
(5)  
(6)  
2Q  
ω1  
π
1
2
V
OUT  
=
ω
A
Cos  
2
2
2Q  
1
2
1
2
ω
=
A
Sin  
( ω )  
1
ω1 + ∆ω  
ω
2Q  
1
V
OUT  
=
2Q  
(
)
1
ω1  
ω1  
2Q ω  
ω1  
π
2
1
For  
<<  
RSSI  
Which is discriminated FM output. (Note that ∆ω is the deviation  
frequency from the carrier ω1.  
The “received signal strength indicator”, or RSSI, of the SA614A  
demonstrates monotonic logarithmic output over a range of 90dB.  
The signal strength output is derived from the summed stage  
currents in the limiting amplifiers. It is essentially independent of the  
IF frequency. Thus, unfiltered signals at the limiter inputs, spurious  
products, or regenerated signals will manifest themselves as RSSI  
outputs. An RSSI output of greater than 250mV with no signal (or a  
very small signal) applied, is an indication of possible regeneration  
or oscillation.  
Ref. Krauss, Raab, Bastian; Solid State Radio Eng.; Wiley, 1980, p.  
311. Example: At 455kHz IF, with +5kHz FM deviation. The  
maximum normalized frequency will be  
455 +5kHz  
= 1.010 or 0.990  
455  
Go to the f vs. normalized frequency curves (Figure 12) and draw a  
vertical straight line at  
In order to achieve optimum RSSI linearity, there must be a 12dB  
insertion loss between the first and second limiting amplifiers. With  
a typical 455kHz ceramic filter, there is a nominal 4dB insertion loss  
in the filter. An additional 6dB is lost in the interface between the  
filter and the input of the second limiter. A small amount of  
ω
= 1.01.  
ω1  
The curves with Q = 100, Q = 40 are not linear, but Q = 20 and less  
shows better linearity for this application. Too small Q decreases  
additional loss must be introduced with a typical ceramic filter. In the  
test circuit used for cellular radio applications (Figure 5) the optimum  
the amplitude of the discriminated FM signal. (Eq. 6)  
Q = 20  
Choose a  
linearity was achieved with a 5.1kresistor from the output of the  
first limiter (Pin 14) to the input of the interstage filter. With this  
resistor from Pin 14 to the filter, sensitivity of 0.25µV for 12dB  
The internal R of the 614A is 40k. From Eq. 1c, and then 1b, it  
results that  
SINAD was achieved. With the 3.6kresistor, sensitivity was  
C
+ C = 174pF and L = 0.7mH.  
S
P
10  
1997 Nov 07  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
demodulation, the maximum data rate is somewhat limited. An  
optimized at 0.22µV for 12dB SINAD with minor change in the RSSI  
internal capacitor limits the RSSI frequency response to about  
100kHz. At high data rates the rise and fall times will not be  
symmetrical.  
linearity.  
Any application which requires optimized RSSI linearity, such as  
spectrum analyzers, cellular radio, and certain types of telemetry,  
will require careful attention to limiter interstage component  
selection. This will be especially true with high IF frequencies which  
require insertion loss or impedance reduction for stability.  
The RSSI output is a current-to-voltage converter similar to the  
audio outputs. However, an external resistor is required. With a  
91kresistor, the output characteristic is 0.5V for a 10dB change in  
the input amplitude.  
At low frequencies the RSSI makes an excellent logarithmic AC  
voltmeter.  
Additional Circuitry  
Internal to the SA614A are voltage and current regulators which  
have been temperature compensated to maintain the performance  
of the device over a wide temperature range. These regulators are  
not accessible to the user.  
For data applications the RSSI is effective as an amplitude shift  
keyed (ASK) data slicer. If a comparator is applied to the RSSI and  
the threshold set slightly above the no signal level, when an in-band  
signal is received the comparator will be sliced. Unlike FSK  
200  
Q = 100  
Φ
175  
150  
125  
100  
75  
Q = 80  
Q = 60  
Q = 20  
Q = 10  
50  
25  
0
0.95  
0.975  
1.0  
1.025  
1.05  
SR00334  
w
wI  
Dw  
wI  
Figure 12. Phase vs Normalized IF Frequency  
+ 1 )  
11  
1997 Nov 07  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
DIP16: plastic dual in-line package; 16 leads (300 mil)  
SOT38-4  
12  
1997 Nov 07  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
SO16: plastic small outline package; 16 leads; body width 3.9 mm  
SOT109-1  
13  
1997 Nov 07  
Philips Semiconductors  
Product specification  
Low power FM IF system  
SA614A  
DEFINITIONS  
Data Sheet Identification  
Product Status  
Definition  
This data sheet contains the design target or goal specifications for product development. Specifications  
may change in any manner without notice.  
Objective Specification  
Formative or in Design  
Preproduction Product  
Full Production  
This data sheet contains preliminary data, and supplementary data will be published at a later date. Philips  
Semiconductors reserves the right to make changes at any time without notice in order to improve design  
and supply the best possible product.  
Preliminary Specification  
Product Specification  
This data sheet contains Final Specifications. Philips Semiconductors reserves the right to make changes  
at any time without notice, in order to improve design and supply the best possible product.  
Philips Semiconductors and Philips Electronics North America Corporation reserve the right to make changes, without notice, in the products,  
including circuits, standard cells, and/or software, described or contained herein in order to improve design and/or performance. Philips  
Semiconductors assumes no responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright,  
or mask work right to these products, and makes no representations or warranties that these products are free from patent, copyright, or mask  
work right infringement, unless otherwise specified. Applications that are described herein for any of these products are for illustrative purposes  
only. PhilipsSemiconductorsmakesnorepresentationorwarrantythatsuchapplicationswillbesuitableforthespecifiedusewithoutfurthertesting  
or modification.  
LIFE SUPPORT APPLICATIONS  
Philips Semiconductors and Philips Electronics North America Corporation Products are not designed for use in life support appliances, devices,  
orsystemswheremalfunctionofaPhilipsSemiconductorsandPhilipsElectronicsNorthAmericaCorporationProductcanreasonablybeexpected  
to result in a personal injury. Philips Semiconductors and Philips Electronics North America Corporation customers using or selling Philips  
Semiconductors and Philips Electronics North America Corporation Products for use in such applications do so at their own risk and agree to fully  
indemnify Philips Semiconductors and Philips Electronics North America Corporation for any damages resulting from such improper use or sale.  
Philips Semiconductors  
811 East Arques Avenue  
P.O. Box 3409  
Copyright Philips Electronics North America Corporation 1997  
All rights reserved. Printed in U.S.A.  
Sunnyvale, California 94088–3409  
Telephone 800-234-7381  
Philips  
Semiconductors  

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