LT5525EUF [Linear]
High Linearity, Low Power Downconverting Mixer; 高线性度，低功率下变频混频器
| 型号： | LT5525EUF |
| 厂家： | 
Linear |
| 描述： | High Linearity, Low Power Downconverting Mixer |
| 文件： | 总12页 (文件大小：192K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT5525
High Linearity, Low Power
Downconverting Mixer
U
FEATURES
DESCRIPTIO
The LT®5525 is a low power broadband mixer optimized
for high linearity applications such as point-to-point data
transmission,highperformanceradiosandwirelessinfra-
structure systems. The device includes an internally 50Ω
matched high speed LO amplifier driving a double-bal-
anced active mixer core. An integrated RF buffer amplifier
providesexcellentLO-RFisolation.TheRFinputbalunand
all associated 50Ω matching components are integrated.
The IF ports can be easily matched across a broad range
of frequencies for use in a wide variety of applications.
■
Wide Input Frequency Range: 0.8GHz to 2.5GHz*
■
Broadband LO and IF Operation
■
High Input IP3: +17.6dBm at 1900MHz
■
Typical Conversion Gain: –1.9dB at 1900MHz
■
High LO-RF and LO-IF Isolation
■
SSB Noise Figure: 15.1dB at 1900MHz
■
Single-Ended 50Ω RF and LO Interface
■
Integrated LO Buffer: –5dBm Drive Level
■
Low Supply Current: 28mA Typ
Enable Function
Single 5V Supply
■
■
The LT5525 offers a high performance alternative to
passive mixers. Unlike passive mixers, which require high
LO drive levels, the LT5525 operates at significantly lower
LO input levels and is much less sensitive to LO power
level variations.
■
16-Lead QFN (4mm × 4mm) Package
U
APPLICATIO S
■
Point-to-Point Data Communication Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
*Operation over a wider frequency range is achievable with reduced performance.
Consult factory for more information.
■
Wireless Infrastructure
■
High Performance Radios
High Linearity Receiver Applications
■
U
TYPICAL APPLICATIO
High Signal Level Frequency Downconversion
IF Output Power and IM3 vs
RF Input Power (Two Input Tones)
V
CC
5V DC
0.01µF
0
–10
–20
V
V
EN
BIAS
CC2
CC1
100pF
P
OUT
1900MHz
1900MHz
140MHz
–30
–40
–50
–60
–70
–80
–90
–100
150nH
+
–
+
–
4:1
RF
RF
IF
IF
LNA
VGA
ADC
1.2pF
150nH
T
= 25°C
= 1900MHz
= 1760MHz
= 140MHz
= –5dBm
A
f
f
f
RF
LO
IF
P
GND
IM3
LO
–5
RF INPUT POWER (dBm/TONE)
+
–
LT5525
LO LO
–20
–15
–10
0
5525 TA01
LO INPUT
–5dBm
5525 TA02
5525f
1
LT5525
W W U W
U
W U
ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER INFORMATION
(Note 1)
TOP VIEW
Supply Voltage ...................................................... 5.5V
Enable Voltage ............................... –0.3V to VCC + 0.3V
LO Input Power ............................................... +10dBm
LO+ to LO– Differential DC Voltage ......................... ±1V
LO+ and LO– Common Mode DC Voltage... –0.5V to VCC
RF Input Power................................................ +10dBm
RF+ to RF– Differential DC Voltage ..................... ±0.13V
RF+ and RF– Common Mode DC Voltage ... –0.5V to VCC
IF+ and IF– Common Mode DC Voltage................... 5.5V
Operating Temperature Range ................ – 40°C to 85°C
Storage Temperature Range ................. –65°C to 125°C
Junction Temperature (TJ)................................... 125°C
ORDER PART
NUMBER
16 15 14 13
LT5525EUF
NC
+
1
2
3
4
12 GND
+
RF
11 IF
17
–
–
RF
NC
IF
10
9
GND
5
6
7
8
UF PART
MARKING
UF PACKAGE
16-LEAD (4mm × 4mm) PLASTIC QFN
5525
TJMAX = 125°C, θJA = 37°C/W
EXPOSED PAD (PIN 17) IS GND,
MUST BE SOLDERED TO PCB.
NC PINS SHOULD BE GROUNDED
Consult LTC Marketing for parts specified with wider operating temperature ranges.
DC ELECTRICAL CHARACTERISTICS
VCC = 5V, EN = 3V, TA = 25°C (Note 3), unless otherwise noted. Test circuit shown in Figure 1.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Power Supply Requirements (V
Supply Voltage
)
CC
(Note 6)
3.6
5
5.3
33
V
mA
µA
Supply Current
V
= 5V
28
CC
Shutdown Current
EN = Low
100
Enable (EN) Low = Off, High = On
EN Input High Voltage (On)
EN Input Low Voltage (Off)
Enable Pin Input Current
3
V
V
0.3
EN = 5V
EN = 0V
55
0.1
µA
µA
Turn-On Time (Note 5)
Turn-Off Time (Note 5)
3
6
µs
µs
(Notes 2, 3)
AC ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
MIN
MIN
TYP
MAX
MAX
UNITS
MHz
RF Input Frequency Range (Note 4)
LO Input Frequency Range (Note 4)
IF Output Frequency Range (Note 4)
Requires RF Matching Below 1300MHz
800 to 2500
500 to 3000
0.1 to 1000
MHz
Requires IF Matching
MHz
VCC = 5V, EN = 3V, TA = 25°C. Test circuit shown in Figure 1. (Notes 2, 3)
PARAMETER
CONDITIONS
Z = 50Ω
TYP
15
UNITS
dB
RF Input Return Loss
LO Input Return Loss
IF Output Return Loss
LO Input Power
O
Z = 50Ω, External DC Blocks
O
15
dB
Z = 50Ω, External Match
O
15
dB
–10 to 0
dBm
5525f
2
LT5525
VCC = 5V, EN = 3V, TA = 25°C, PRF = –15dBm (–15dBm/tone for 2-tone
AC ELECTRICAL CHARACTERISTICS
in Figure 1. (Notes 2, 3)
IIP3 tests, ∆f = 1MHz), fLO = fRF – 140MHz, PLO = –5dBm, IF output measured at 140MHz, unless otherwise noted. Test circuit shown
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Conversion Gain
f
f
f
f
= 900MHz
= 1900MHz
= 2100MHz
= 2500MHz
–2.6
–1.9
–2.0
–2.0
dB
dB
dB
dB
RF
RF
RF
RF
Conversion Gain vs Temperature
Input 3rd Order Intercept
T = –40°C to 85°C
–0.020
dB/°C
A
f
f
f
f
= 900MHz
= 1900MHz
= 2100MHz
= 2500MHz
21.0
17.6
17.6
12.0
dBm
dBm
dBm
dBm
RF
RF
RF
RF
Single Sideband Noise Figure
f
f
f
f
= 900MHz
= 1900MHz
= 2100MHz
= 2500MHz
14.0
15.1
15.6
15.6
dB
dB
dB
dB
RF
RF
RF
RF
LO to RF Leakage
LO to IF Leakage
f
f
= 500MHz to 1000MHz
= 1000MHz to 3000MHz
≤–50
≤–43
dBm
dBm
LO
LO
f
f
= 500MHz to 1400MHz
= 1400MHz to 3000MHz
≤–50
≤–39
dBm
dBm
LO
LO
RF to LO Isolation
RF to IF Isolation
f
= 500MHz to 3000MHz
>38
dB
RF
f
f
f
f
= 900MHz
= 1900MHz
= 2100MHz
= 2500MHz
62
42
40
33
dB
dB
dB
dB
RF
RF
RF
RF
Input 1dB Compression
f
f
f
f
= 900MHz
= 1900MHz
= 2100MHz
= 2500MHz
7.6
4
4
dBm
dBm
dBm
dBm
RF
RF
RF
RF
3
2RF-2LO Output Spurious Product
900MHz: f = 830MHz at –15dBm
–63
–53
–45
–42
dBc
dBc
dBc
dBc
RF
(f = f + f /2)
1900MHz: f = 1830MHz at –15dBm
RF
LO
IF
RF
2100MHz: f = 2030MHz at –15dBm
RF
2500MHz: f = 2430Hz at –15dBm
RF
3RF-3LO Output Spurious Product
(f = f + f /3)
900MHz: f = 806.67MHz at –15dBm
–74
–59
–59
–60
dBc
dBc
dBc
dBc
RF
1900MHz: f = 1806.67MHz at –15dBm
RF
LO
IF
RF
2100MHz: f = 2006.67MHz at –15dBm
RF
2500MHz: f = 2406.67Hz at –15dBm
RF
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 4: Operation over a wider frequency range is possible with reduced
performance. Consult the factory for information and assistance.
Note 2: The performance is measured with the test circuit shown in
Figure 1. For 900MHz measurements, C1 = 3.9pF. For all other
measurements, C1 is not used.
Note 5: Turn-on and turn-off times correspond to a change in the output
level of 40dB.
Note 6: The part is operable below 3.6V with reduced performance.
Note 3: Specifications over the –40°C to 85°C temperature range are
assured by design, characterization and correlation with statistical process
controls.
5525f
3
LT5525
W U
VCC = 5V, EN = 3V, TA = 25°C, fRF = 1900MHz,
TYPICAL AC PERFOR A CE CHARACTERISTICS
PRF = –15dBm (–15dBm/tone for 2-tone IIP3 tests, ∆f = 1MHz), fLO = fRF – 140MHz, PLO = –5dBm, IF output measured at 140MHz,
unless otherwise noted. Test circuit shown in Figure 1.
Conversion Gain and IIP3
Conversion Gain and IIP3
vs RF Frequency (Low Side LO)
vs RF Frequency (High Side LO)
SSB NF vs RF Frequency
25
25
20
19
18
17
16
15
14
13
12
11
12
20
15
10
5
20
15
10
5
IIP3
IIP3
HIGH SIDE LO
LOW SIDE LO
25°C
25°C
85°C
85°C
–40°C
–40°C
GAIN
GAIN
0
0
–5
–5
1900 2100
1900 2100
2300 2500
900 1100 1300 1500 1700
2300 2500
900 1100 1300 1500 1700
900
1100 1300 1500
1700
1900 2500
2100 2300
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
RF FREQUENCY (MHz)
5525 G01
5525 G02
5525 G03
Conversion Gain and IIP3
vs LO Input Power
SSB Noise Figure
vs LO Input Power
LO-IF, LO-RF and RF-LO Leakage
vs Frequency
25
20
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
20
19
18
17
16
15
14
13
12
25°C
85°C
–40°C
15
10
IIP3
LO-RF
RF-LO
25°C
85°C
–40°C
5
0
LO-IF
GAIN
–5
–16 –14 –12 –10 –8 –6 –4 –2
LO INPUT POWER (dBm)
0
2
4
500
1000
1500
2000
2500
3000
–6 –4
–14 –12 –10 –8
LO INPUT POWER (dBm)
–2
0
2
FREQUENCY (MHz)
5525 G04
5525 G06
5525 G05
Conversion Gain and IIP3
vs Supply Voltage
RF, LO and IF Port Return Loss
vs Frequency
IF Output Power and IM3 vs RF
Input Power (Two Input Tones)
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
0
–5
25
20
15
10
P
OUT
RF
LO
–10
–15
–20
–25
–30
25°C
85°C
–40°C
IIP3
5
0
IF
IM3
GAIN
25°C
85°C
–40°C
–5
4.4
SUPPLY VOLTAGE (V)
5.2 5.6
0
1000 1500 2000 2500 3000
FREQUENCY (MHz)
–20
–15
–10
0
2.8 3.2
3.6
4
4.8
500
–5
RF INPUT POWER (dBm/TONE)
5525 G08
5525 G09
5525 G07
5525f
4
LT5525
W U
VCC = 5V, EN = 3V, TA = 25°C, fRF = 1900MHz,
PRF = –15dBm (–15dBm/tone for 2-tone IIP3 tests, ∆f = 1MHz), fLO = fRF – 140MHz, PLO = –5dBm, IF output measured at 140MHz,
TYPICAL AC PERFOR A CE CHARACTERISTICS
unless otherwise noted. Test circuit shown in Figure 1.
IFOUT, 2 × 2 and 3 × 3 Spurs
vs RF Input Power
2 × 2 and 3 × 3 Spurs
vs LO Input Power
10
0
–30
–40
T
= 25°C
A
IF OUT
f
f
= 1760MHz
LO
IF
f
RF
= 1900MHz
= 140MHz
–10
–20
–30
–40
–50
–50
–60
–70
3RF-3LO
f
= 1806.67MHz
RF
2RF-2LO
= 1830MHz
f
RF
2RF-2LO
= 1830MHz
–60
–70
f
RF
–80
–90
–100
3RF-3LO
= 1806.67MHz
–80
–90
T
= 25°C
f
RF
A
f
f
= 1760MHz
LO
IF
= 140MHz
–100
–12
–8
–4
4
–20
–15
–10
–5
0
–16
0
RF INPUT POWER (dBm)
LO INPUT POWER (dBm)
5525 G10
5525 G11
W U
Test circuit shown in Figure 1.
TYPICAL DC PERFOR A CE CHARACTERISTICS
Supply Current vs Supply Voltage
Shutdown Current vs Supply Voltage
20
15
10
5
32
30
28
26
24
22
20
18
16
25°C
85°C
–40°C
25°C
85°C
–40°C
0
14
2.8 3.2
3.6
4
4.4 4.8 5.2 5.6
2.8 3.2 3.6
4
5.6
4.4 4.8 5.2
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
5525 G13
5525 G12
5525f
5
LT5525
U
U
U
PI FU CTIO S
NC (Pins 1, 4, 8, 13, 16): Not Connected Internally. These
pinsshouldbegroundedonthecircuitboardforimproved
LO-to-RF and LO-to-IF isolation.
RF+, RF– (Pins 2, 3): Differential Inputs for the RF Signal.
OneRFinputpinmaybeDCconnectedtoalowimpedance
ground to realize a 50Ω single-ended input at the other RF
pin. No external matching components are required. A DC
voltage should not be applied across these pins, as they
are internally connected through a transformer winding.
GND (Pins 9, 12): Ground. These pins are internally
connected to the Exposed Pad for better isolation. They
should be connected to ground on the circuit board,
though they are not intended to replace the primary
grounding through the Exposed Pad of the package.
IF– and IF+ (Pins 10, 11): Differential Outputs for the IF
Signal. An impedance transformation may be required to
match the outputs. These pins must be connected to VCC
through impedance matching inductors, RF chokes or a
transformer center-tap.
LO–, LO+ (Pins 14, 15): Differential Inputs for the Local
Oscillator Signal. The LO input is internally matched to
50Ω. The LO can be driven with a single-ended source
through either LO input pin, with the other LO input pin
connected to ground. There is an internal DC resistance
across these pins of approximately 480Ω. Thus, a DC
blocking capacitor should be used if the signal source has
a DC voltage present.
EN (Pin 5): Enable Pin. When the input voltage is higher
than 3V, the mixer circuits supplied through Pins 6, 7, 10
and 11 are enabled. When the input voltage is less than
0.3V, all circuits are disabled. Typical enable pin input
current is 55µA for EN = 5V and 0.1µA when EN = 0V.
V
CC1 (Pin 6): Power Supply Pin for the LO Buffer Circuits.
Typical current consumption is 11mA. This pin should be
externally connected to the other VCC pins and decoupled
with 1µF and 0.01µF capacitors.
Exposed Pad (Pin 17): Circuit Ground Return for the
EntireIC.Thismustbesolderedtotheprintedcircuitboard
ground plane.
VCC2 (Pin 7): Power Supply Pin for the Bias Circuits.
Typical current consumption is 2.5mA. This pin should be
externally connected to the other VCC pins and decoupled
with 1µF and 0.01µF capacitors.
W
BLOCK DIAGRA
17
15 14
+
–
LO
LO
EXPOSED
PAD
HIGH
SPEED
LO BUFFER
GND
LINEAR
AMPLIFIER
12
11
10
9
+
–
RF
RF
+
IF
2
3
–
IF
GND
DOUBLE-
BALANCED
MIXER
BIAS
EN
V
V
CC1
CC2
5
7
6
5525 BD
5525f
6
LT5525
TEST CIRCUITS
RF
GND
ER = 4.4
0.018"
0.062"
LO
IN
1760MHz
DC
0.018"
GND
16
15 14
13
NC
+
–
17 NC LO LO
NC
C1
OPTIONAL
1
2
12
11
10
9
L3
T2
GND
RF
+
1
2
3
5
4
IN
+
C4
RF
IF
1900MHz
C3
L2
LT5525
–
3
4
IF
OUT
140MHz
IF
–
RF
NC
GND
EN
V
V
NC
CC1 CC2
5
6
7
8
EN
V
CC
5526 F01
900MHz INPUT MATCHING:
C1: 3.9pF
C2
C8
REF DES
VALUE
—
SIZE
0402
0402
0402
0402
0603
1608
SM-22
PART NUMBER
C1
C2
C3
C4
C8
Frequency Dependent
AVX 04023C103JAT
AVX 04025A1R2BAT
AVX 04025A101JAT
0.01µF
1.2pF
100pF
1µF
Taiyo Yuden LMK107BJ105MA
Toko LL1608-FSR15J
L2, L3
T2
150nH
4:1
M/A-COM ETC4-1-2
Figure 1. Test Schematic
W U U
APPLICATIO S I FOR ATIO
U
T
he LT5525 consists of a double-balanced mixer, RF
RF Input Port
balun, RF buffer amplifier, high speed limiting LO buffer
and bias/enable circuits. The IC has been optimized for
downconverter applications with RF input signals from
0.8GHz to 2.5GHz and LO signals from 500MHz to 3GHz.
With proper matching, the IF output can be operated at
frequencies from 0.1MHz to 1GHz. Operation over a
wider frequency range is possible, though with reduced
performance.
The mixer’s RF input, shown in Figure 2, consists of an
integrated balun and a high linearity differential amplifier.
The primary terminals of the balun are connected to the
RF+ andRF– pins(Pins2and3, respectively). Thesecond-
arysideofthebalunisinternallyconnectedtotheamplifier’s
differential inputs.
For single-ended operation, the RF+ pin is grounded and
the RF– pin becomes the RF input. It is also possible to
ground the RF– pin and drive the RF+ pin, if desired. If the
RF source has a DC voltage present, then a coupling
capacitor must be used in series with the RF input pin.
Otherwise, excessive DC current could damage the pri-
mary winding of the balun.
The RF, LO and IF ports are all differential, though the RF
and LO ports are internally matched to 50Ω for single-
ended drive. The LT5525 is characterized and production
tested using single-ended RF and LO inputs. Low side or
high side LO injection can be used.
5525f
7
LT5525
APPLICATIO S I FOR ATIO
W U U
U
25
20
+
LT5525
RF
2
IIP3
15
10
5
OPTIONAL SERIES
REACTANCE FOR
LOW BAND OR
HIGH BAND
SSB NF
T
f
= 25°C
A
IF
RF
IN
= 140MHz
MATCHING
–
RF
LOW SIDE LO
HIGH SIDE LO
3
5525 F02
0
GAIN
Figure 2. RF Input Schematic
–5
1050 1100
800 850 900 950 1000
1150 1200
RF FREQUENCY (MHz)
As shown in Figure 3, the RF input return loss with no
external matching is greater than 12dB from 1.3GHz to
2.3GHz. The RF input match can be shifted down to
800MHzbyaddingaseries3.9pFcapacitorattheRFinput.
A series 1.2nH inductor can be added to shift the match up
to 2.5GHz. Measured return losses with these external
components are also shown in Figure 3.
5525 F04
Figure 4. Typical Gain, IIP3 and NF with
Series 3.9pF Matching Capacitor
Table 1. RF Port Input Impedance vs Frequency
FREQUENCY
(MHz)
INPUT
REFLECTION COEFFICIENT
IMPEDANCE
MAG
0.675
0.551
0.478
0.398
0.321
0.244
0.177
0.131
0.138
0.187
0.250
0.311
0.369
0.435
ANGLE
174
124
106
90
50
10.4 + j2.63
18.1 + j23.7
25.8 + j30.7
36.5 + j34.5
48.4 + j33.3
59.5 + j25.7
65.9 + j13.1
65.0 – j1.0
0
500
700
–5
NO RF
900
MATCHING
–10
1100
1300
1500
1700
1900
2100
2300
2500
2700
3000
74
57
–15
–20
33
–3
59.0 – j12.2
50.2 – j19.0
41.8 – j22.1
34.9 – j22.7
29.1 – j21.9
23.2 – j19.1
–47
–79
–97
–109
–118
–130
SERIES 1.2nH
–25
SERIES 3.9pF
–30
500
1000
1500
2000
2500
3000
RF FREQUENCY (MHz)
5525 F03
Figure 3. RF Input Return Loss Without and
with External Matching Components
A broadband RF input match can be easily realized by
using both the series capacitor and series inductor as
shown in Figure 5. This network provides good return loss
at both lower and higher frequencies simultaneously,
while maintaining good mid-band return loss. The broad-
band return loss is plotted in Figure 6. The return loss is
better than 12dB from 700MHz to 2.6GHz using the
element values of Figure 5.
Figure4illustratesthetypicalconversiongain,IIP3andNF
performance of the LT5525 when the RF input match is
shifted lower in frequency using an external series 3.9pF
capacitor on the RF input.
RF input impedance and reflection coefficient (S11) ver-
sus frequency are shown in Table 1. The listed data is
referenced to the RF– pin with the RF+ pin grounded (no
external matching). This information can be used to simu-
late board-level interfacing to an input filter, or to design
a broadband input matching network.
LO Input Port
The LO buffer amplifier consists of high speed limiting
differential amplifiers designed to drive the mixer core for
high linearity. The LO+ and LO– pins are designed for
5525f
8
LT5525
W U U
APPLICATIO S I FOR ATIO
U
0
+
LT5525
RF
2
–5
–10
–15
C5
4.7pF
L3
1.5nH
RF
IN
–
RF
3
5525 F05
Figure 5. Wideband RF Input Matching
–20
0
500 1000 1500 2000 2500 3000
FREQUENCY (MHz)
0
5525 F08
–5
Figure 8. LO Input Return Loss
NO EXTERNAL
RF MATCHING
–10
–15
The LO port input impedance and reflection coefficient
(S11) versus frequency are shown in Table 2. The listed
dataisreferencedtotheLO+ pinwiththeLO–pingrounded.
SERIES 1.5nH
AND 4.7pF
–20
–25
–30
Table 2. Single-Ended LO Input Impedance
FREQUENCY
(MHz)
INPUT
REFLECTION COEFFICIENT
IMPEDANCE
MAG
0.686
0.457
0.276
0.171
0.166
0.187
0.281
0.214
ANGLE
–30
100
250
93.1 – j121
55.8 – j54
47.7 – j28
42.3 – j14
38.5 – j9.3
35.8 – j7.8
34.8 – j7.8
34.2 – j8.7
500
1000
1500
2000
2500
3000
–57
RF FREQUENCY (MHz)
5525 F06
500
–79
1000
1500
2000
2500
3000
–110
–135
–146
–148
–149
Figure 6. RF Input Return Loss Using
Wideband Matching Network
single-ended drive, though differential drive can be used if
desired. The LO input is internally matched to 50Ω. A
simplified schematic for the LO input is shown in Figure 7.
Measured return loss is shown in Figure 8.
IF Output Port
If the LO source has a DC voltage present, then a coupling
capacitor should be used in series with the LO input pin
due to the internal resistive match.
A simplified schematic of the IF output circuit is shown in
Figure 9. The output pins, IF+ and IF–, are internally con-
nected to the collectors of the mixer switching transistors.
Both pins must be biased at the supply voltage, which can
be applied through the center-tap of a transformer or
–
LT5525
LO
14
15
20pF
LT5525
IF
OUT
V
480Ω 54Ω
20pF
CC
L3
T2
4:1
+
IF
11
10
LO
IN
575Ω
50Ω
+
C3
V
CC
L2
LO
0.7pF
–
IF
5525 F07
V
CC
5525 F09
Figure 7. LO Input Schematic
Figure 9. IF Output with External Matching
5525f
9
LT5525
W U U
U
APPLICATIO S I FOR ATIO
throughimpedance-matchinginductors.EachIFpindraws
about 7.5mA of supply current (15mA total). For optimum
single-endedperformance,thesedifferentialoutputsmust
becombinedexternallythroughanIFtransformerorbalun.
LT5525
0.7nH
0.7nH
L3
+
–
IF
11
10
C
IF
0.7pF
R
IF
574Ω
R
L
200Ω
C3
L2
IF
An equivalent small-signal model for the output is shown
in Figure 10. The output impedance can be modeled as a
574Ω resistor (RIF) in parallel with a 0.7pF capacitor. For
most applications, the bond-wire inductance (0.7nH per
side) can be ignored.
5525 F10
Figure 10. IF Output Small Signal Model
element network. This circuit is shown in Figure 11, where
L11, L12, C11 and C12 form a narrowband bridge balun.
These element values are selected to realize a 180° phase
shift at the desired IF frequency, and can be estimated
using the equations below. In this case, the load resis-
tance, RL, is 50Ω.
The external components, C3, L2 and L3 form an imped-
ance transformation network to match the mixer output
impedance to the input impedance of transformer T2. The
values for these components can be estimated using the
equationsbelow,alongwiththeimpedancevalueslistedin
Table 3. As an example, at an IF frequency of 140MHz and
RL =200Ω(usinga4:1transformerforT2withanexternal
50Ω load),
RIF •RL
L11= L12 =
ω
n = RIF/RL = 574/200 = 2.87
Q = √(n – 1) = 1.368
XC = RIF/Q = 420Ω
C = 1/(ω • XC) = 2.71pF
C3 = C – CIF = 2.01pF
XL = RL • Q = 274Ω
1
C11= C12 =
ω RIF •RL
I
nductor L13 or L14 provides a DC path between VCC and
the IF+ pin. Only one of these inductors is required. Low
cost multilayer chip inductors are adequate for L11, L12
and L13. If L14 is used instead of L13, a larger value is
usually required, which may require the use of a wire-
wound inductor. Capacitor C13 is a DC block which can
also be used to adjust the impedance match. Capacitor
C14 is a bypass capacitor.
L2 = L3 = XL/2ω = 156nH
Table 3. IF Differential Impedance (Parallel Equivalent)
FREQUENCY
(MHz)
OUTPUT
REFLECTION COEFFICIENT
IMPEDANCE
MAG
0.840
0.840
0.840
0.838
0.834
0.831
0.829
0.822
0.814
ANGLE
–1.8
70
575|| – j3.39k
574|| – j1.67k
572|| – j977
561|| – j519
537|| – j309
525|| – j267
509|| – j229
474|| – j181
435|| – j147
140
–3.5
C12
L11
C11
+
–
240
–5.9
IF
IF
C13
C14
450
–11.1
–18.6
–21.3
–24.8
–31.3
–38.0
IF
L14
OPT
OUT
50Ω
750
860
L13
OPT
1000
1250
1500
L12
V
CC
5525 F11
Figure 11. Narrowband Bridge IF Balun
Low Cost Output Match
Actual component values for IF frequencies of 240MHz,
360MHz and 450MHz are listed in Table 4. Typical IF port
return loss for these examples is shown in Figure 12.
For low cost applications in which the required fractional
bandwidth of the IF output is less than 25%, it may be
possible to replace the output transformer with a lumped-
5525f
10
LT5525
W U U
APPLICATIO S I FOR ATIO
U
Table 4. Component Values for Lumped Balun
IF FREQ (MHz) L11, L12 (nH) C11, C12 (pF) C13 (pF) L14 (nH)
Conversion gain and IIP3 performance with an RF fre-
quency of 1900MHz are plotted vs IF frequency in Figure
13.TheseresultsshowthattheusableIFbandwidthforthe
lumped element balun is greater than 60MHz, assuming
tight tolerance matching components. Contact the factory
for applications assistance with this circuit.
240
360
450
100
68
3.9
2.7
2.2
100
10
560
270
180
56
8.2
0
20
15
10
5
20
19
18
17
16
15
14
13
12
11
10
IIP3
–5
T
= 25°C
A
–10
–15
f
f
P
P
= f – f
LO RF IF
RF
= 1900MHz
= –5dBm
= –15dBm
LO
RF
T
= 25°C
A
GAIN
–20
–25
0
f
= f – f
LO RF IF
P
P
240MHz
360MHz
450MHz
= –5dBm
= –15dBm
LO
RF
–5
200
300
350
400
450
500
200
300
350
400
450
500
250
250
1200
1600 1800 2000 2200 2400 2600
RF FREQUENCY (MHz)
1400
FREQUENCY (MHz)
IF FREQUENCY (MHz)
5525 F12
5525 F13
5525 F14
Figure 12. Typical IF Return Loss
Performance with 240MHz,
360MHz and 450MHz Lumped
Element Baluns
Figure 13. Typical Gain and IIP3 vs
IF Frequency with 240MHz,
360MHz and 450MHz Lumped
Element Baluns
Figure 14. Typical IIP3 vs RF
Frequency with Lumped Element
Baluns and IF Frequencies of
240MHz, 360MHz and 450MHz
U
TYPICAL APPLICATIO S
Evaluation Board Layouts
Top Layer Silkscreen
Top Layer Metal
5525f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
11
LT5525
U
PACKAGE DESCRIPTIO
UF Package
16-Lead Plastic QFN (4mm × 4mm)
(Reference LTC DWG # 05-08-1692)
0.75 ± 0.05
R = 0.115
TYP
0.55 ± 0.20
4.00 ± 0.10
(4 SIDES)
15
16
0.72 ±0.05
PIN 1
TOP MARK
(NOTE 6)
1
2
4.35 ± 0.05 2.15 ± 0.05
2.15 ± 0.10
(4-SIDES)
(4 SIDES)
2.90 ± 0.05
PACKAGE
OUTLINE
(UF) QFN 1103
0.30 ± 0.05
0.65 BSC
0.200 REF
0.30 ±0.05
0.65 BSC
0.00 – 0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
NOTE:
BOTTOM VIEW—EXPOSED PAD
1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGGC)
2. DRAWING NOT TO SCALE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON THE TOP AND BOTTOM OF PACKAGE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
RELATED PARTS
PART NUMBER DESCRIPTION
Infrastructure
COMMENTS
LT5512
LT5514
DC-3GHz High Signal Level Down Converting Mixer
21dBm IIP3, Integrated LO Buffer
Ultralow Distortion, IF Amplifier/ADC Driver with Digitally
Controlled Gain
850MHz Bandwidth, 47dBm OIP3 at 100MHz, 10.5dB to 33dB Gain
Control Range
LT5519
LT5520
LT5521
LT5522
LT5526
0.7GHz to 1.4GHz High Linearity Upconverting Mixer
1.3GHz to 2.3GHz High Linearity Upconverting Mixer
3.7GHz Very High Linearity Mixer
17.1dBm IIP3 at 1GHz, Integrated RF Output Transformer with 50Ω
Matching, Single-Ended LO and RF Ports Operation
15.9dBm IIP3 at 1.9GHz, Integrated RF Output Transformer with 50Ω
Matching, Single-Ended LO and RF Ports Operation
24.2dBm IIP3 at 1.95GHz, 12.5dB SSBNF, –42dBm LO Leakage,
Supply Voltage = 3.15V to 5.25V
600MHz to 2.7GHz High Signal Level Downconverting Mixer
High Linearity, Low Power Downconverting Mixer
4.5V to 5.25V Supply, 25dBm IIP3 at 900MHz, NF = 12.5dB,
50Ω Single-Ended RF and LO Ports
16.5dBm IIP3 at 900MHz, NF = 11dB, Supply Current = 28mA, 3.6V
to 5.3V Supply
RF Power Detectors
LTC5508
LTC5532
LT5534
300MHz to 7GHz RF Power Detector
300MHz to 7GHz Precision RF Power Detector
50MHz to 3GHz RF Power Detector with 60dB Dynamic Range ±1dB Output Variation over Temperature, 38ns Response Time
44dB Dynamic Range, Temperature Compensated, SC70 Package
Precision V
Offset Control, Adjustable Gain and Offset
OUT
LTC5535
600MHz to 7GHz RF Power Detector
12MHz Baseband BW, Precision Offset with Adjustable Gain and Offset
Wide Bandwidth ADCs
LTC1749
LTC1750
12-Bit, 80Msps ADC
500MHz BW S/H, 71.8dB SNR, 87dB SFDR
14-Bit, 80Msps ADC
500MHz BW S/H, 75.5dB SNR, 90dB SFDR, 2.25V or 1.35V
Input Ranges
P-P
P-P
LTC2222/
LTC2223
12-Bit, 105Msps/80Msps ADC
10-Bit/12-Bit, 135Msps ADC
Low Power 775MHz BW S/H, 61dB SNR, 75dB SFDR ±0.5V or ±1V
Input
LTC2224/
LTC2234
Low Power 775MHz BW S/H, 61dB SNR, 75dB SFDR ±0.5V or ±1V
Input
5525f
LT/TP 1004 1K • PRINTED IN THE USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
12
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
©LINEAR TECHNOLOGY CORPORATION 2004
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