FEATURES
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LT5575
800MHz to 2.7GHz
High Linearity Direct Conversion
Quadrature Demodulator
DESCRIPTION
The LT
®
5575 is an 800MHz to 2.7GHz direct conversion
quadrature demodulator optimized for high linearity
receiver applications. It is suitable for communications
receivers where an RF signal is directly converted into I
and Q baseband signals with bandwidth up to 490MHz.
The LT5575 incorporates balanced I and Q mixers, LO
buffer amplifiers and a precision, high frequency quadrature
phase shifter. The integrated on-chip broadband transform-
ers provide 50Ω single-ended interfaces at the RF and LO
inputs. Only a few external capacitors are needed for its
application in an RF receiver system.
The high linearity of the LT5575 provides excellent spur-
free dynamic range for the receiver. This direct conversion
demodulator can eliminate the need for intermediate fre-
quency (IF) signal processing, as well as the corresponding
requirements for image filtering and IF filtering. Channel
filtering can be performed directly at the outputs of the I
and Q channels. These outputs can interface directly to
channel-select filters (LPFs) or to baseband amplifiers.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
*Operation over a wider frequency range is possible with reduced performance. Consult
the factory.
Input Frequency Range: 0.8GHz to 2.7GHz*
50Ω Single-Ended RF and LO Ports
High IIP3: 28dBm at 900MHz, 22.6dBm at 1.9GHz
High IIP2: 54.1dBm at 900MHz, 60dBm at 1.9GHz
Input P1dB: 13.2dBm at 900MHz
I/Q Gain Mismatch: 0.04dB Typical
I/Q Phase Mismatch: 0.4° Typical
Low Output DC Offsets
Noise Figure: 12.8dB at 900MHz, 12.7dB at 1.9GHz
Conversion Gain: 3dB at 900MHz, 4.2dB at 1.9GHz
Very Few External Components
Shutdown Mode
16-Lead QFN 4mm
×
4mm Package with
Exposed Pad
APPLICATIONS
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Cellular/PCS/UMTS Infrastructure
RFID Reader
High Linearity Direct Conversion I/Q Receiver
TYPICAL APPLICATION
High Signal-Level I/Q Demodulator for Wireless Infrastructure
+5V
BPF
LNA
BPF
RF
INPUT
V
CC
RF
LT5575
VGA
0°
I
OUT–
A/D
Conversion Gain, NF, IIP3 and IIP2
vs LO Input Power at 1900MHz
35
IIP2
GAIN (dB), NF (dB), IIP3 (dBm)
70
60
IIP3
50
IIP2 (dBm)
40
DSB NF
–40°C
25°C
85°C
30
20
10
0
I
OUT+
LPF
30
25
20
15
10
5
0
–15
LO INPUT
LO
0°/90°
90°
Q
OUT
+
LPF
VGA
A/D
CONV
GAIN
Q
OUT–
ENABLE
EN
5575 TA01
–5
–10
0
LO INPUT POWER (dBm)
5
5575 TA01b
5575f
1
LT5575
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
Q
OUT+
Q
OUT–
12 V
CC
17
11 GND
10 LO
9
5
EN
6
V
CC
7
V
CC
8
V
CC
GND
I
OUT+
GND 1
RF 2
GND 3
GND 4
I
OUT–
Power Supply Voltage ..............................................5.5V
Enable Voltage ................................ –0.3V to V
CC
+ 0.3V
LO Input Power ....................................................10dBm
RF Input Power ....................................................20dBm
RF Input DC Voltage ...............................................±0.1V
LO Input DC Voltage ..............................................±0.1V
Operating Ambient Temperature ..............–40°C to 85°C
Storage Temperature Range...................–65°C to 125°C
Maximum Junction Temperature .......................... 125°C
CAUTION: This part is sensitive to electrostatic discharge
(ESD). It is very important that proper ESD precautions
be observed when handling the LT5575.
16 15 14 13
UF PACKAGE
16-LEAD (4mm
×
4mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 37°C/W
EXPOSED PAD (PIN #17) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LT5575EUF#PBF
TAPE AND REEL
LT5575EUF#TRPBF
PART MARKING
5575
PACKAGE DESCRIPTION
16-Lead (4mm
×
4mm) QFN
TEMPERATURE RANGE
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Supply Voltage
Supply Current
Shutdown Current
Turn On Time
Turn Off Time
EN = High (On)
EN = Low (Off)
EN Input Current
Output DC Offset Voltage
( | I
OUT+
– I
OUT–
|, | Q
OUT+
– Q
OUT–
| )
Output DC Offset Variation
vs Temperature
V
ENABLE
= 5V
EN = Low
CONDITIONS
V
CC
= +5V, T
A
= 25°C, unless otherwise noted. (Note 3)
MIN
4.5
132
<1
120
750
2
1
120
<9
38
TYP
MAX
5.25
155
100
UNITS
V
mA
µA
ns
ns
V
V
µA
mV
µV/°C
f
LO
= 1900MHz, P
LO
= 0dBm
–40°C to 85°C
5575f
2
LT5575
AC ELECTRICAL CHARACTERISTICS
PARAMETER
RF Input Frequency Range
LO Input Frequency Range
Baseband Frequency Range
Baseband I/Q Output Impedance
RF Input Return Loss
LO Input Return Loss
LO Input Power
Single-Ended
Z
O
= 50Ω, 1.5GHz to 2.7GHz,
Internally Matched
Z
O
= 50Ω, 1.5GHz to 2.7GHz,
Internally Matched
CONDITIONS
No External Matching (High Band)
With External Matching (Low Band, Mid Band)
No External Matching (High Band)
With External Matching (Low Band, Mid Band)
Test circuit shown in Figure 1. (Notes 2, 3)
MIN
TYP
1.5 to 2.7
0.8 to 1.5
1.5 to 2.7
0.8 to 1.5
DC to 490
65Ω// 5pF
>10
>10
–13 to 5
dB
dB
dBm
MAX
UNITS
GHz
GHz
GHz
GHz
MHz
AC ELECTRICAL CHARACTERISTICS
PARAMETER
Conversion Gain
CONDITIONS
V
CC
= +5V, EN = High, T
A
= 25°C, P
RF
= –10dBm (–10dBm/tone for
2-tone IIP2 and IIP3 tests), Baseband Frequency = 1MHz (0.9MHz and 1.1MHz for 2-tone tests), P
LO
= 0dBm, unless otherwise noted.
(Notes 2, 3, 6)
MIN
TYP
3
4.2
3.5
2
12.8
12.7
13.6
15.7
28
22.6
22.7
23.3
54.1
60
56
52.3
13.2
11.2
11
12.3
0.03
0.01
0.04
0.04
0.5
0.4
0.6
0.2
–60.8
–64.6
–60.2
–51.2
MAX
UNITS
dB
dB
dB
dB
dB
dB
dB
dB
dBm
dBm
dBm
dBm
dBm
dBm
dBm
dBm
dBm
dBm
dBm
dBm
dB
dB
dB
dB
°
°
°
°
dBm
dBm
dBm
dBm
5575f
Voltage Gain, R
LOAD
= 1kΩ
R
F
= 900MHz (Note 5)
R
F
= 1900MHz
R
F
= 2100MHz
R
F
= 2500MHz
R
F
= 900MHz (Note 5)
R
F
= 1900MHz
R
F
= 2100MHz
R
F
= 2500MHz
R
F
= 900MHz (Note 5)
R
F
= 1900MHz
R
F
= 2100MHz
R
F
= 2500MHz
R
F
= 900MHz (Note 5)
R
F
= 1900MHz
R
F
= 2100MHz
R
F
= 2500MHz
R
F
= 900MHz (Note 5)
R
F
= 1900MHz
R
F
= 2100MHz
R
F
= 2500MHz
R
F
= 900MHz (Note 5)
R
F
= 1900MHz
R
F
= 2100MHz
R
F
= 2500MHz
R
F
= 900MHz (Note 5)
R
F
= 1900MHz
R
F
= 2100MHz
R
F
= 2500MHz
R
F
= 900MHz (Note 5)
R
F
= 1900MHz
R
F
= 2100MHz
R
F
= 2500MHz
Noise Figure (Double-Side Band, Note 4)
Input 3rd-Order Intercept
Input 2nd-Order Intercept
Input 1dB Compression
I/Q Gain Mismatch
I/Q Phase Mismatch
LO to RF Leakage
3
LT5575
AC ELECTRICAL CHARACTERISTICS
PARAMETER
RF to LO Isolation
CONDITIONS
R
F
= 900MHz (Note 5)
R
F
= 1900MHz
R
F
= 2100MHz
R
F
= 2500MHz
V
CC
= +5V, EN = High, T
A
= 25°C, P
RF
= –10dBm (–10dBm/tone for
2-tone IIP2 and IIP3 tests), Baseband Frequency = 1MHz (0.9MHz and 1.1MHz for 2-tone tests), P
LO
= 0dBm, unless otherwise noted.
(Notes 2, 3, 6)
MIN
TYP
59.7
57.1
59.5
53.1
MAX
UNITS
dBc
dBc
dBc
dBc
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
Tests are performed as shown in the configuration of Figure 1.
Note 3:
Specifications over the –40˚C to 85˚C temperature range are
assured by design, characterization and correlation with statistical
process control.
Note 4:
DSB Noise Figure is measured with a small-signal noise source
at the baseband frequency of 15MHz without any filtering on the RF input
and no other RF signal applied.
Note 5:
900MHz performance is measured with external RF and LO
matching. The optional output capacitors C1-C4 (10pF) are also used for
best IIP2 performance.
Note 6:
For these measurements, the complementary outputs (e.g., I
OUT +
,
I
OUT –
) were combined using a 180˚ phase shift combiner.
Note 7:
Large-signal noise figure is measured at an output frequency of
198.7MHz with RF input signal at f
LO
–1MHz. Both RF and LO input signals
are appropriately bandpass filtered, as well as baseband output.
5575f
4
LT5575
TYPICAL AC PERFORMANCE CHARACTERISTICS
V
CC
= 5V, EN = High, T
A
= 25ºC, P
RF
= –10dBm
(–10dBm/tone for 2-tone IIP2 and IIP3 tests), f
BB
= 1MHz (0.9MHz and 1.1MHz for 2-tone tests), P
LO
= 0dBm, unless otherwise noted.
Test Circuit Shown in Figure 1 (Note 6).
Conversion Gain, NF and IIP3
vs Frequency
35
GAIN (dB), NF (dB), IIP3 (dBm)
30
25
LOW
MID
20 BAND BAND
15
10
5
0
800
CONV GAIN
DSB NF
IIP3
60
IIP2 (dBm)
I
CC
(mA)
HIGH BAND
55
50
45
40
800
–40°C
25°C
85°C
1100 1400 1700 2000 2300 2600
RF INPUT FREQUENCY (MHz)
5575 G02
IIP2 vs Frequency
70
65
160
150
140
Supply Current
vs Supply Voltage
–40°C
25°C
85°C
85°C
25°C
130
120
– 40°C
110
100
4.50
1100 1400 1700 2000 2300 2600
RF INPUT FREQUENCY (MHz)
5575 G01
4.75
5.00
5.25
SUPPLY VOLTAGE (V)
5.50
5575 G03
Conversion Gain
vs RF Input Power
5
1900MHz
4
CONVERSION GAIN (dB)
GAIN MISMATCH (dB)
900MHz
3
2500MHz
2
1
0
–1
–15
0.2
0.1
0.0
–0.1
–0.2
0.3
I/Q Gain Mismatch
vs RF Input Frequency
f
BB
= 1MHz
–40°C
25°C
85°C
PHASE MISMATCH (DEG)
3
2
1
0
1
2
I/Q Phase Mismatch
vs RF Input Frequency
f
BB
= 1MHz
–40°C
25°C
85°C
–10
10
–5
0
5
RF INPUT POWER (dBm)
15
5575 G04
–0.3
800
1100 1400 1700 2000 2300 2600
RF FREQUENCY (MHz)
5575 G05
3
800
1100 1400 1700 2000 2300 2600
RF FREQUENCY (MHz)
5575 G06
RF-LO Isolation
vs RF Input Power
70
65
RF-LO ISOLATION (dBc)
LO-RF LEAKAGE (dBm)
60
55
50
45
40
–16
900MHz
1900MHz
2500MHz
– 40
– 45
–50
–55
– 60
–65
–70
–75
–12
–8
–4
0
RF INPUT POWER (dBm)
4
8
5575 G07
LO-RF Leakage
vs LO Input Power
6
5
CONV. GAIN (dB)
4
3
2
1
0
Conversion Gain
vs Baseband Frequency
f
LO
= 1901MHz
– 40°C
25°C
85°C
2500MHz
900MHz
1900MHz
– 80
–15
–5
–10
0
LO INPUT POWER (dBm)
5
5575 G08
0.1
1.0
10
100
BASEBAND FREQUENCY (MHz)
1000
5575 G09
5575f
5
FPGA/CPLD
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