LT5517
40MHz to 900MHz
Quadrature Demodulator
FEATURES
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DESCRIPTIO
RF Input Frequency Range: 40MHz to 900MHz
High IIP3: 21dBm at 800MHz
High IIP2: 58dBm at 800MHz
I/Q Gain Mismatch: 0.3dB Max
I/Q Phase Mismatch: 0.7°
Noise Figure: 12.4dB at 800MHz
Conversion Gain: 3.3dB at 800MHz
Baseband Bandwidth: 130MHz
Single Ended, 50Ω Matched 2XLO Input
Shutdown Mode
16-Lead QFN (4mm
×
4mm) Package
with Exposed Pad
The LT
®
5517 is a 40MHz to 900MHz quadrature demodu-
lator optimized for high linearity receiver applications
where high dynamic range is important. It is suitable for
communications receivers where an RF or IF signal is
directly converted into I and Q baseband signals with a
bandwidth up to 130MHz. The LT5517 incorporates bal-
anced I and Q mixers, LO buffer amplifiers and a precision,
broadband quadrature generator derived from an on-chip
divide-by-two circuit.
The superior linearity and low noise performance of the
LT5517 is achieved across its full frequency range. A well-
balanced divide-by-two circuit generates precision quadra-
ture LO carriers to drive the I mixer and the Q mixer.
Consequently, the outputs of the I-channel and the
Q-channel are well matched in amplitude, and their phases
are 90° apart. The LT5517 also provides excellent 50Ω
impedance matching at the 2XLO port across its entire
frequency range.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
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Wireless Infrastructure
High Linearity Direct Conversion I/Q Receiver
High Linearity I/Q Demodulator
TYPICAL APPLICATIO
BPF
LNA
BPF
5V
RF
+
V
CC
LT5517
I
OUT+
I
OUT–
LPF
VGA
RF
–
0°
20
0
P
OUT
, IM3, IM2 (dBm/TONE)
DSP
Q
OUT+
÷2
90°
ENABLE
EN
Q
OUT–
5517 F01
LPF
VGA
2xLO
INPUT
2xLO
Figure 1. High Signal-Level I/Q Demodulator for 450MHz Infrastructure Receiver
U
I/Q Output Power, IM3, IM2
vs RF Input Power
P
OUT
–20
T
A
= 25°C
P
2XLO
= –10dBm
–40 f
2XLO
= 1602MHz
f
RF1
= 799.9MHz
f
RF2
= 800.1MHz
–60
–80
–100
–18
IM3
IM2
–14
–10
–6
–2
RF INPUT POWER (dBm)
2
5517 F01b
U
U
5517f
1
LT5517
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
Q
OUT +
Q
OUT –
I
OUT +
I
OUT –
V
CC
V
CC
UF PACKAGE
16-LEAD (4mm
×
4mm) PLASTIC QFN
EXPOSED PAD (PIN 17) IS GND,
MUST BE SOLDERED TO PCB
T
JMAX
= 125°C,
θ
JA
= 37°C/W
V
CC
EN
Power Supply Voltage ............................................ 5.5V
Enable Voltage ....................................................0V, V
CC
2XLO Voltage (10dBm Equivalent) ..........................
±1V
RF
+
to RF
–
Differential Voltage
(10dBm Equivalent) .................................................
±2V
Operating Ambient Temperature ..............–40°C to 85°C
Storage Temperature Range ................. – 65°C to 125°C
Maximum Junction Temperature .......................... 125°C
ORDER PART
NUMBER
12 V
CC
16 15 14 13
GNDRF 1
RF
+
2
RF
–
LT5517EUF
3
17
11 GND
10 2XLO
9
GND
GNDRF 4
5
6
7
8
UF PART
MARKING
5517
Consult LTC Marketing for parts specified with wider operating temperature ranges.
AC ELECTRICAL CHARACTERISTICS
PARAMETER
RF Frequency Range
2XLO Frequency Range
2XLO Power
2XLO Port Return Loss
Conversion Gain
Gain Variation vs Temperature
Noise Figure
Input 3rd Order Intercept
Input 2nd Order Intercept
Input 1dB Compression
Baseband Bandwidth
I/Q Gain Mismatch
I/Q Phase Mismatch
Output Impedance
2XLO to RF Leakage
LO to RF Leakage
RF to 2XLO Isolation
(Note 4)
(Note 4)
Differential
CONDITIONS
T
A
= 25°C. V
CC
= 5V, EN = V
CC
, f
RF1
= 799.9MHz, f
RF2
= 800.1MHz,
f
2XLO
= 1602MHz, P
2XLO
= –10dBm, unless otherwise noted. (Notes 2, 3) (Test circuit shown in Figure 2)
MIN
TYP
40 to 900
80 to 1800
–15 to 0
Internally Matched to a 50Ω Source
Voltage Gain, Load Impedance = 1kΩ
–40°C to 85°C
2-Tone, –10dBm/Tone,
∆f
= 200kHz
2-Tone, –10dBm/Tone,
∆f
= 200kHz
0
20
3.3
0.01
12.4
21
58
10
130
–0.3
–3.5
0.03
0.7
120
–69
–80
63
0.3
3.5
MAX
UNITS
MHz
MHz
dBm
dB
dB
dB/°C
dB
dBm
dBm
dBm
MHz
dB
deg
Ω
dBm
dBm
dB
2
U
5517f
W
U
U
W W
W
LT5517
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
(Note 5)
(Note 5)
CONDITIONS
T
A
= 25°C. V
CC
= 5V unless otherwise noted.
MIN
4.5
70
90
0.1
200
300
1.6
1.3
2
0.5
7
30
TYP
MAX
5.25
110
20
UNITS
V
mA
µA
ns
ns
V
V
µA
mV
µV/°C
f
LO
= 1602MHz, P
LO
= –10dBm
– 40°C to 85°C
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Tests are performed as shown in the configuration of Figure 2.
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:
Measured at P
2XLO
= –10dBm and output frequency = 1MHz.
Note 5:
Turn ON and Turn OFF times are based on rise and fall times of the
output baseband voltage with RF input power of –10dBm.
TYPICAL PERFOR A CE CHARACTERISTICS
f
RF
= 800MHz, P
2XLO
= –10dBm, unless otherwise noted. (Test circuit shown in Figure 2)
Conv Gain, NF, IIP3
vs RF Input Frequency
25
IIP3
T
A
= 85°C
T
A
= 25°C
Supply Current vs Supply Voltage
110
GAIN (dB), NF (dB), IIP3 (dBm)
100
SUPPLY CURRENT (mA)
90
15
NF
10
80
T
A
= –40°C
IIP2 (dBm)
70
60
4.5
5
4.75
5.25
SUPPLY VOLTAGE (V)
U W
5517 G01
IIP2 vs RF Input Frequency
80
P
2XLO
= –10dBm
V
CC
= 5V
T
A
= 25°C
20
P
2XLO
= –10dBm
V
CC
= 5V
T
A
= 25°C
70
60
50
5
CONV GAIN
40
0
5.5
30
0 100 200 300 400 500 600 700 800 900
RF INPUT FREQUENCY (MHz)
5517 G02
0 100 200 300 400 500 600 700 800 900
RF INPUT FREQUENCY (MHz)
5517 G03
5517f
3
LT5517
TYPICAL PERFOR A CE CHARACTERISTICS
f
RF
= 800MHz, P
2XLO
= –10dBm, unless otherwise noted. (Test circuit shown in Figure 2)
I/Q Output Power, IM3
vs RF Input Power
20
0
f
2XLO
= 1602MHz f
RF1
= 799.9MHz
V
CC
= 5V
f
RF2
= 800.1MHz
OUTPUT POWER
–20
–40
IM3
–60
–80
–100
–18
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
–14
–10
–6
–2
RF INPUT POWER (dBm)
2
5517 G04
P
OUT
, IM3 (dBm/TONE)
GAIN MISMATCH (dB)
0.40
0.20
0
–0.20
–0.40
–0.60
–0.80
0
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
100 200 300 400 500 600 700 800 900
RF INPUT FREQUENCY (MHz)
5517 G05
PHASE MISMATCH (DEGREE)
Conv Gain, IIP3 vs Supply Voltage
28
24
f
2XLO
= 1602MHz f
RF1
= 799.9MHz
V
CC
= 5V
f
RF2
= 800.1MHz
14
CONV GAIN (dB), IIP3 (dBm)
CONV GAIN (dB), IIP3 (dBm)
20
16
12
8
4
0
4.5
IIP3
NF (dB)
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
CONV GAIN
4.75
5.25
SUPPLY VOLTAGE (V)
5
IIP2 vs 2XLO Input Power
70
65
60
IIP2 (dBm)
f
2XLO
= 1602MHz
V
CC
= 5V
T
A
= 85°C
LO-RF LEAKAGE (dBm)
55
50
45
40
35
30
–15
–12
T
A
= 25°C
T
A
= –40°C
f
2XLO
= 1600MHz
–80
f
2XLO
= 800MHz
–90
2XLO-RF LEAKAGE (dBm)
–3
–6
2XLO INPUT POWER (dBm)
–9
4
U W
5517 G07
I/Q Gain Mismatch
vs RF Input Frequency
P
2XLO
= –10dBm
0.60 f
BB
= 1MHz
V
CC
= 5V
0.80
I/Q Phase Mismatch
vs RF Input Frequency
6
P
2XLO
= –10dBm
f
BB
= 1MHz
4 V
CC
= 5V
2
0
–2
–4
–6
0 100 200 300 400 500 600 700 800 900
RF INPUT FREQUENCY (MHz)
5517 G06
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
NF vs 2XLO Input Power
T
A
= 25°C
V
CC
= 5V
Conv Gain, IIP3
vs 2XLO Input Power
24
f
RF
= 800MHz
f
RF
= 400MHz
12
20
16
12
8
4
0
–15
f
2XLO
= 1602MHz
V
CC
= 5V
f
RF1
= 799.9MHz
f
RF2
= 800.1MHz
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
IIP3
10
f
RF
= 200MHz
f
RF
= 40MHz
8
6
CONV GAIN
5.5
4
–15
–12
–6
–3
–9
2XLO INPUT POWER (dBm)
0
5517 G08
–12
–9
–6
–3
2XLO INPUT POWER (dBm)
0
5517 G09
LO-RF Leakage
vs 2XLO Input Power
–60
–70
T
A
= 25°C
V
CC
= 5V
–60
–70
–80
–90
2XLO-RF Leakage
vs 2XLO Input Power
T
A
= 25°C
V
CC
= 5V
f
2XLO
= 1600MHz
f
2XLO
= 800MHz
–100
–110
f
2XLO
= 80MHz
–100
–110
f
2XLO
= 80MHz
0
5517 G10
–120
–15
–12
–9
–6
–3
2XLO INPUT POWER (dBm)
0
5517 G11
–120
–15
–12
–9
–6
–3
2XLO INPUT POWER (dBm)
0
5517 G12
5517f
LT5517
TYPICAL PERFOR A CE CHARACTERISTICS
f
RF
= 800MHz, P
2XLO
= –10dBm, unless otherwise noted. (Test circuit shown in Figure 2)
RF-LO Isolation
vs RF Input Power
120
110
RF-LO ISOLATION (dB)
6
f
RF
= 40MHz
CONV GAIN (dB)
90
80
f
RF
= 400MHz
70
f
RF
= 800MHz
60
T
A
= 25°C
V
CC
= 5V
–10
–5
0
5
10
5517 G13
2
RETURN LOSS (dB)
100
50
–15
RF INPUT POWER (dBm)
PI FU CTIO S
GNDRF (Pins 1, 4):
Ground Pins for RF Termination.
These pins are not internally connected, and should be
connected to the PCB ground plane for best RF isolation.
RF
+
, RF
–
(Pins 2, 3):
Differential RF Input Pins. These pins
are internally biased to 2.30V. These two pins should be
DC blocked when connected to ground or other matching
components. The inputs can be terminated in a single-
ended configuration, but differential input drive is pre-
ferred for best performance. An external matching network
is required for impedance transformation.
EN (Pin 5):
Enable Pin. When the input voltage is higher
than 1.6V, the circuit is completely turned on. When the
input voltage is less than 1.3V, the circuit is turned off.
V
CC
(Pins 6, 7, 8, 12):
Power Supply Pins. These pins
should be decoupled using 1000pF and 0.1µF capacitors.
GND (Pins 9, 11):
Ground Pins. These pins are internally
tied together and to the Exposed Pad. They should be
connected to the PCB ground plane.
2XLO (Pin 10):
2XLO Input Pin. This pin is internally
biased to 1V. The input signal’s frequency should be twice
that of the desired demodulator LO frequency. The pin
should be AC coupled with an external DC blocking
capacitor.
Q
OUT–
, Q
OUT+
(Pins 13, 14):
Differential Baseband Output
Pins of the Q-Channel. The internal DC bias voltage is
V
CC
– 0.78V for each pin.
I
OUT–
, I
OUT+
(Pins 15, 16):
Differential Baseband Output
Pins of the I-Channel. The internal DC bias voltage is
V
CC
– 0.78V for each pin.
Exposed Pad (Pin 17):
Ground Return for the Entire IC.
This pin must be soldered to the printed circuit board
ground plane.
U W
Conv Gain
vs Baseband Frequency
f
2XLO
= 1602MHz
V
CC
= 5V
T
A
= –40°C
RF, 2XLO Port Return Loss
vs Frequency
0
4
–5
T
A
= 25°C
T
A
= 85°C
–10
RF
–15
LO
–20
0
–2
–4
0.1
1
10
100
BASEBAND FREQUENCY (MHz)
1000
5517 G14
–25
0
0.40
1.20
1.60
0.80
FREQUENCY (GHz)
2
5517 G15
U
U
U
5517f
5
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