FEATURES
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LT5571
620MHz – 1100MHz High
Linearity Direct Quadrature
Modulator
DESCRIPTION
The LT
®
5571 is a direct I/Q modulator designed for high
performance wireless applications, including wireless
infrastructure. It allows direct modulation of an RF signal
using differential baseband I and Q signals. It supports
RFID, GSM, EDGE, CDMA, CDMA2000, and other systems.
It may also be configured as an image reject upconvert-
ing mixer by applying 90° phase-shifted signals to the I
and Q inputs. The high impedance I/Q baseband inputs
consist of voltage-to-current converters that in turn drive
double-balanced mixers. The outputs of these mixers are
summed and applied to an on-chip RF transformer, which
converts the differential mixer signals to a 50Ω single-
ended output. The four balanced I and Q baseband input
ports are intended for DC-coupling from a source with a
common-mode voltage at about 0.5V. The LO path consists
of an LO buffer with single-ended input, and precision
quadrature generators that produce the LO drive for the
mixers. The supply voltage range is 4.5V to 5.25V.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
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Direct Conversion from Baseband to RF
High Output: –4.2dB Conversion Gain
High OIP3: 21.7dBm at 900MHz
Low Output Noise Floor at 20MHz Offset:
No RF: –159dBm/Hz
P
OUT
= 4dBm: –153.3dBm/Hz
Low Carrier Leakage: –42dBm at 900MHz
High Image Rejection: –53dBc at 900MHz
3-Ch CDMA2000 ACPR: –70.4dBc at 900MHz
Integrated LO Buffer and LO Quadrature Phase
Generator
50Ω AC-Coupled Single-Ended LO and RF Ports
High Impedance DC Interface to Baseband Inputs
with 0.5V Common Mode Voltage
16-Lead QFN 4mm
×
4mm Package
APPLICATIONS
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RFID Interrogators
GSM, CDMA, CDMA2000 Transmitters
Point-to-Point Wireless Infrastructure Tx
Image Reject Up-Converters for Cellular Bands
Low-Noise Variable Phase-Shifter for 620MHz to
1100MHz Local Oscillator Signals
TYPICAL APPLICATION
Direct Conversion Transmitter Application
5V
V
CC
I-DAC
V-I
I-CH
0°
EN
Q-CH
Q-DAC
BASEBAND
GENERATOR
VCO/SYNTHESIZER
V-I
–80
5571 TA01a
CDMA2000 ACPR, AltCPR and Noise vs RF
Output Power at 900MHz for 1 and 3 Carriers
–40
LT5571
100nF
×2
RF = 620MHz
TO 1100MHz
ACPR, AltCPR (dBc)
PA
DOWNLINK TEST
MODEL 64 DPCH
3-CH ACPR
3-CH AltCPR
1-CH
ACPR
–110
NOISE FLOOR AT 30MHz OFFSET (dBm/Hz)
–50
–120
–60
–130
90°
BALUN
–70
1-CH NOISE
1-CH AltCPR
3-CH NOISE
–90
–30
–140
–150
–160
–10
–5
0
–25
–20
–15
RF OUTPUT POWER PER CARRIER (dBm)
5571 TA01b
5571f
1
LT5571
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW
BBMI
BBPI
GND
V
CC
12 GND
17
11 RF
10 GND
9
5
BBMQ
6
GND
7
BBPQ
8
V
CC
GND
Supply Voltage .........................................................5.5V
Common-Mode Level of BBPI, BBMI and
BBPQ, BBMQ .......................................................0.6V
Operating Ambient Temperature
(Note 2) ............................................... –40°C to 85°C
Storage Temperature Range................... –65°C to 125°C
Voltage on any Pin
Not to Exceed...................... –500mV to V
CC
+ 500mV
Note: The baseband input pins should not be left floating.
16 15 14 13
EN 1
GND 2
LO 3
GND 4
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 PART NUMBER
LT5571EUF
UF PART MARKING
5571
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL
RF Output (RF)
f
RF
S
22, ON
S
22, OFF
NFloor
RF Frequency Range
RF Frequency Range
RF Output Return Loss
RF Output Return Loss
RF Output Noise Floor
PARAMETER
V
CC
= 5V, EN = High, T
A
= 25°C, f
LO
= 900MHz, f
RF
= 902MHz,
P
LO
= 0dBm. BBPI, BBMI, BBPQ, BBMQ CM input voltage = 0.5V
DC
, Baseband Input Frequency = 2MHz, I & Q 90° shifted (upper
sideband selection). P
RF(OUT)
= –10dBm, unless otherwise noted. (Note 3)
CONDITIONS
–3dB Bandwidth
–1dB Bandwidth
EN = High (Note 6)
EN = Low (Note 6)
No Input Signal (Note 8)
P
OUT
= 4dBm (Note 9)
P
OUT
= 4dBm (Note 10)
20 • Log (V
OUT, 50Ω
/V
IN, DIFF, I or Q
)
1V
P-P DIFF
CW Signal, I and Q
(Note 17)
(Note 7)
(Notes 13, 14)
(Notes 13, 15)
(Note 16)
EN = High, P
LO
= 0dBm (Note 16)
EN = Low, P
LO
= 0dBm (Note 16)
MIN
TYP
0.62 to 1.1
0.65 to 1.04
12.7
11.6
–159
–153.3
–152.9
–4.2
–0.2
–25.5
8.1
63.8
21.7
–53
–42
–61
MAX
UNITS
GHz
GHz
dB
dB
dBm/Hz
dBm/Hz
dBm/Hz
dB
dBm
dB
dBm
dBm
dBm
dBc
dBm
dBm
G
V
P
OUT
G
3LO vs LO
OP1dB
OIP2
OIP3
IR
LOFT
Conversion Voltage Gain
Absolute Output Power
3 • LO Conversion Gain Difference
Output 1dB Compression
Output 2nd Order Intercept
Output 3rd Order Intercept
Image Rejection
Carrier Leakage (LO Feedthrough)
5571f
2
LT5571
ELECTRICAL CHARACTERISTICS
LO Input (LO)
f
LO
P
LO
S
11, ON
S
11, OFF
NF
LO
G
LO
IIP3
LO
BW
BB
V
CMBB
R
IN
I
DC, IN
P
LO-BB
IP1dB
ΔG
I/Q
Δϕ
I/Q
V
CC
I
CC(ON)
I
CC(OFF)
t
ON
t
OFF
Enable
Shutdown
LO Frequency Range
LO Input Power
LO Input Return Loss
LO Input Return Loss
LO Input Referred Noise Figure
LO to RF Small Signal Gain
LO Input 3rd Order Intercept
Baseband Bandwidth
DC Common-Mode Voltage
Differential Input Resistance
Baseband Static Input Current
Carrier Feedthrough on BB
Input 1dB Compression Point
I/Q Absolute Gain Imbalance
I/Q Absolute Phase Imbalance
Supply Voltage
Supply Current
Supply Current, Shutdown Mode
Turn-On Time
Turn-Off Time
Input High Voltage
Input High Current
Input Low Voltage
EN = High
EN = 0V
EN = Low to High (Note 11)
EN = High to Low (Note 12)
EN = High
EN = 5V
EN = Low
1
230
0.5
0.4
1.4
4.5
(Note 4)
No Baseband Signal (Note 4)
Differential Peak-to-Peak (Note 7)
EN = High (Note 6)
EN = Low (Note 6)
at 900MHz (Note 5)
at 900MHz (Note 5)
at 900MHz (Note 5)
–3dB Bandwidth
Externally Applied (Note 4)
–10
0.5 to 1.2
0
–10.9
–2.6
14.3
18.5
–4.8
400
0.5
90
–24
–42
2.9
0.013
0.24
5
97
5.25
120
100
0.6
5
GHz
dBm
dB
dB
dB
dB
dBm
MHz
V
kΩ
µA
dBm
V
P-P,DIFF
dB
Deg
V
mA
µA
µs
µs
V
µA
V
V
CC
= 5V, EN = High, T
A
= 25°C, f
LO
= 900MHz, f
RF
= 902MHz,
P
LO
= 0dBm. BBPI, BBMI, BBPQ, BBMQ CM input voltage = 0.5V
DC
, Baseband Input Frequency = 2MHz, I & Q 90° shifted (upper
sideband selection). P
RF(OUT)
= –10dBm, unless otherwise noted. (Note 3)
Baseband Inputs (BBPI, BBMI, BBPQ, BBMQ)
Power Supply (V
CC
)
Enable (EN), Low = Off, High = On
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:
Specifications over the –40°C to 85°C temperature range are
assured by design, characterization and correlation with statistical process
controls.
Note 3:
Tests are performed as shown in the configuration of Figure 7.
Note 4:
At each of the four baseband inputs BBPI, BBMI, BBPQ and BBMQ.
Note 5:
V(BBPI) – V(BBMI) = 1V
DC
, V(BBPQ) – V(BBMQ) = 1V
DC
.
Note 6:
Maximum value within –1dB bandwidth.
Note 7:
An external coupling capacitor is used in the RF output line.
Note 8:
At 20MHz offset from the LO signal frequency.
Note 9:
At 20MHz offset from the CW signal frequency.
Note 10:
At 5MHz offset from the CW signal frequency.
Note 11:
RF power is within 10% of final value.
Note 12:
RF power is at least 30dB lower than in the ON state.
Note 13:
Baseband is driven by 2MHz and 2.1MHz tones. Drive level is set
in such a way that the two resulting RF tones are –10dBm each.
Note 14:
IM2 measured at LO frequency + 4.1MHz
Note 15:
IM3 measured at LO frequency + 1.9MHz and LO frequency +
2.2MHz.
Note 16:
Amplitude average of the characterization data set without image
or LO feed-through nulling (unadjusted).
Note 17:
The difference in conversion gain between the spurious signal at
f = 3 • LO – BB versus the conversion gain at the desired signal at f = LO +
BB for BB = 2MHz and LO = 900MHz.
5571f
3
LT5571
TYPICAL PERFORMANCE CHARACTERISTICS
V
CC
= 5V, EN = High, T
A
= 25°C, f
LO
= 900MHz,
f
RF
= 902MHz, P
LO
= 0dBm. BBPI, BBMI, BBPQ, BBMQ CM input voltage = 0.5V
DC
, Baseband Input Frequency f
BB
= 2MHz, I & Q 90°
shifted, without image or LO feedthrough nulling. f
RF
= f
BB
+ f
LO
(upper sideband selection). P
RF(OUT)
= –10dBm (–10dBm/tone for 2-
tone measurements), unless otherwise noted. (Note 3)
RF Output Power vs LO Frequency
at 1V
P-P
Differential Baseband
Drive
2
0
VOLTAGE GAIN (dB)
85°C
100
25°C
90
–40°C
RF OUTPUT POWER (dBm)
SUPPLY CURRENT (mA)
–2
–4
–6
–8
–10
80
4.50
–12
550
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
5571 G02
Supply Current vs Supply Voltage
110
Voltage Gain vs LO Frequency
–2
–4
–6
–8
–10
–12
–14
–16
550
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
5558 G03
4.75
5.00
SUPPLY VOLTAGE (V)
5.25
5571 G01
Output IP3 vs LO Frequency
26
24
22
OIP3 (dBm)
20
18
16
14
12
550
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
5571 G04
Output IP2 vs LO Frequency
75
70
65
OIP2 (dBm)
60
55
50
45
550
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
5571 G05
Output 1dB Compression vs
LO Frequency
10
8
6
4
2
0
–2
550
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
5571 G06
f
BB, 1
= 2MHz
f
BB, 2
= 2.1MHz
f
IM2
= f
BB
,
1
+ f
BB
,
2
+ f
LO
f
BB
,
1
= 2MHz
f
BB
,
2
= 2.1MHz
LO Feedthrough to RF Output vs
LO Frequency
–40
–40
2 • LO Leakage to RF Output vs
2 • LO Frequency
–45
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
OP1dB (dBm)
3 • LO Leakage to RF Output vs
3 • LO Frequency
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
LO FEEDTHROUGH (dBm)
2 • LO LEAKAGE (dBm)
3 • LO LEAKAGE (dBm)
–42
–50
–45
–55
–44
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
5571 G07
–50
–60
–46
–55
–65
–48
550
–60
1.1
1.3
1.5 1.7 1.9 2.1 2.3
2 • LO FREQUENCY (GHz)
2.5
5571 G08
–70
1.65 1.95 2.25 2.55 2.85 3.15 3.5 3.75
3 • LO FREQUENCY (GHz)
5571 G09
5571f
4
LT5571
TYPICAL PERFORMANCE CHARACTERISTICS
V
CC
= 5V, EN = High, T
A
= 25°C, f
LO
= 900MHz,
f
RF
= 902MHz, P
LO
= 0dBm. BBPI, BBMI, BBPQ, BBMQ CM input voltage = 0.5V
DC
, Baseband Input Frequency f
BB
= 2MHz, I & Q 90°
shifted, without image or LO feedthrough nulling. f
RF
= f
BB
+ f
LO
(upper sideband selection). P
RF(OUT)
= –10dBm (–10dBm/tone for 2-
tone measurements), unless otherwise noted. (Note 3)
LO and RF Port Return Loss vs
Frequency
0
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
S
11
(dB)
LO PORT, EN = LOW
–10
LO PORT, EN = HIGH, P
LO
= 0dBm
Noise Floor vs RF Frequency
–157
f
LO
= 900MHz (FIXED)
NO BASEBAND SIGNAL
IMAGE REJECTION (dBc)
–30
Image Rejection vs LO Frequency
–158
NOISE FLOOR (dBm/Hz)
–35
–159
–40
–20
RF PORT,
EN = LOW
RF PORT,
EN = HIGH,
P
LO
= 0dBm
RF PORT,
EN = HIGH,
NO LO
LO PORT,
EN = HIGH,
P
LO
= –10dBm
–160
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
650 750 850 950 1050 1150 1250
RF FREQUENCY (MHz)
5571 G10
–45
–161
–30
–50
–162
550
–55
550
650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
5571 G11
–40
550
650 750 850 950 1050 1150 1250
FREQUENCY (MHz)
5571 G12
Absolute I/Q Gain Imbalance vs
LO Frequency
0.3
ABSOLUTE I/Q PHASE IMBALANCE (DEG)
ABSOLUTE I/Q GAIN IMBALANCE (dB)
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
3
Absolute I/Q Phase Imbalance vs
LO Frequency
–2
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
–4
–6
VOLTAGE GAIN (dB)
–8
–10
–12
–14
–16
–18
0
550
650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
5571 G14
Voltage Gain vs LO Power
0.2
2
0.1
1
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
–16 –12 –8
–4
0
4
LO INPUT POWER (dBm)
8
5571 G15
0
550
650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
5571 G13
–20
–20
Output IP3 vs LO Power
24
22
LO FEEDTHROUGH (dBm)
20
OIP3 (dBm)
18
16
14
12
10
–20
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
f
BB, 1
= 2MHz
f
BB, 2
= 2.1MHz
4
–16 –12 –8
–4
0
LO INPUT POWER (dBm)
8
5571 G16
LO Feedthrough vs LO Power
–38
–40
–42
–44
–46
–48
–50
–20
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
–16 –12 –8
–4
0
4
LO INPUT POWER (dBm)
8
5571 G17
Image Rejection vs LO Power
–35
–40
IMAGE REJECTION (dBc)
–45
–50
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
–16 –12 –8
–4
0
4
LO INPUT POWER (dBm)
8
5571 G18
–55
–60
–20
5571f
5
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