FEATURES
■
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LT5568-2
GSM/EDGE Optimized,
High Linearity Direct
Quadrature Modulator
DESCRIPTIO
The LT
®
5568-2 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
GSM, EDGE, CDMA, CDMA2000 and other systems that
operate in the 850MHz to 965MHz band. It may be config-
ured as an image reject upconverting mixer, by applying
90° phase-shifted signals to the I and Q inputs. The 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 level of 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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Optimized Image Rejection for 850MHz to 965MHz
High OIP3: +22.9dBm at 900MHz
Low Output Noise Floor at 5MHz Offset:
No RF: –159.4dBm/Hz
P
OUT
= 4dBm: –153dBm/Hz
Integrated LO Buffer and LO Quadrature Phase
Generator
50Ω AC-Coupled Single-Ended LO and RF Ports
50Ω DC Interface to Baseband Inputs
Low Carrier Leakage: –43dBm at 900MHz
High Image Rejection: –52dBc at 900MHz
16-Lead 4mm
×
4mm QFN Package
APPLICATIO S
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■
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Infrastructure Tx for GSM/Cellular Bands
Image Reject Up-Converters for Cellular Bands
Low-Noise Variable Phase-Shifter for 700MHz to
1050MHz Local Oscillator Signals
RFID Reader
TYPICAL APPLICATIO
850MHz to 965MHz Direct Conversion Transmitter Application
V
CC
LT5568-2
I-DAC
V-I
I-CHANNEL
0°
EN
Q-CHANNEL
Q-DAC
V-I
90°
BALUN
5V
100nF
x2
RF = 850MHz
TO 965MHz
5
4
EVM (%RMS)
PA
3
2
EVM
1
BASEBAND
GENERATOR
55682 TA01
VCO/SYNTHESIZER
0
–10
U
U
U
GSM EVM and Noise
vs RF Output Power at 900MHz
–96
–98
NOISE FLOOR AT 6MHz
OFFSET (dBc/100kHz)
NOISE
–100
–102
–104
4
–8 –6 –4 –2
0
2
GSM RF OUTPUT POWER (dBm)
6
–106
55682 TA02
55682f
1
LT5568-2
ABSOLUTE
(Note 1)
AXI U RATI GS
BBMQ
GND
BBPQ
Supply Voltage .........................................................5.5V
Common Mode Level of BBPI, BBMI and
BBPQ, BBMQ .......................................................2.5V
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
CAUTION: This part is sensitive to ESD. It is very
important that proper ESD precautions be observed
when handling the LT5568-2.
BBMI
BBPI
GND
16 15 14 13
EN 1
GND 2
LO 3
GND 4
5
6
7
8
V
CC
17
12 GND
11 RF
10 GND
9
GND
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
LT5568-2EUF#PBF
TAPE AND REEL
LT5568-2EUF#TRPBF
PART MARKING
55682
PACKAGE DESCRIPTION
16-Lead (4mm
×
4mm) Plastic 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 non-standard 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/
V
CC
= 5V, EN = High, T
A
= 25°C, f
LO
= 900MHz, f
RF
= 902MHz, P
LO
= 0dBm.
BBPI, BBMI, BBPQ, BBMQ inputs 0.54V
DC
, Baseband Input Frequency = 2MHz, I&Q 90° shifted (upper side-band selection).
P
RF, OUT
= –10dBm, unless otherwise noted. (Note 3)
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
–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)
P
OUT
/P
IN, I&Q
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)
–9
0.6 to 1.1
0.7 to 1
–16
–18
–159.4
–153
–152.6
–6.8
–6.8
–2.8
–23
8.6
59
22.9
–3
GHz
GHz
dB
dB
dBm/Hz
dBm/Hz
dBm/Hz
dB
dB
dBm
dB
dBm
dBm
dBm
55682f
ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
MIN
V
CC
G
P
G
V
P
OUT
G
3LO vs LO
OP1dB
OIP2
OIP3
Conversion Power Gain
Conversion Voltage Gain
Absolute Output Power
3 • LO Conversion Gain Difference
Output 1dB Compression
Output 2nd Order Intercept
Output 3rd Order Intercept
2
U
W W
W
PIN CONFIGURATION
TOP VIEW
TYP
MAX
UNITS
LT5568-2
ELECTRICAL CHARACTERISTICS
SYMBOL
IR
LOFT
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, SE
P
LO2BB
IP1dB
V
CC
I
CC, ON
I
CC, OFF
t
ON
t
OFF
Enable
Sleep
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
Single-Ended Input Resistance
Carrier Feedthrough on BB
Input 1dB Compression Point
Supply Voltage
Supply Current
Supply Current, Sleep Mode
Turn-On Time
Turn-Off Time
Input High Voltage
Input High Current
Input Low Voltage
Input Low Current
EN = High
EN = 0V
EN = Low to High (Note 11)
EN = High to Low (Note 12)
EN = High
EN = 5V
EN = Low
EN = 0V
1.0
245
0.5
0.01
0.3
1.4
EN = High (Note 6)
EN = Low (Note 6)
(Note 5) at 900MHz
(Note 5) at 900MHz
(Note 5) at 900MHz
–3dB Bandwidth
(Note 4)
(Note 4)
P
OUT
= 0 (Note 4)
Differential Peak-to-Peak (Notes 7, 18)
4.5
80
–10
0.6 to 1.1
0
–15
–2.5
14.7
14.7
–3
380
0.54
47
–38
4.3
5
110
5.25
145
100
5
GHz
dBm
dB
dB
dB
dB
dBm
MHz
V
Ω
dBm
V
P-P, DIFF
V
mA
µA
µs
µs
V
µA
V
µA
PARAMETER
Image Rejection
Carrier Leakage
(LO Feedthrough)
V
CC
= 5V, EN = High, T
A
= 25°C, f
LO
= 900MHz, f
RF
= 902MHz, P
LO
= 0dBm.
BBPI, BBMI, BBPQ, BBMQ inputs 0.54V
DC
, Baseband Input Frequency = 2MHz, I&Q 90° shifted (upper side-band selection).
P
RF, OUT
= –10dBm, unless otherwise noted. (Note 3)
CONDITIONS
f
BB
= 100kHz (Note 16)
EN = High, P
LO
= 0dBm (Note 16)
EN = Low, P
LO
= 0dBm (Note 16)
MIN
TYP
–52
–43
–65
MAX
UNITS
dBc
dBm
dBm
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:
On 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 850MHz to 965MHz.
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 feedthrough 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.
Note 18:
The input voltage corresponding to the output P1dB.
55682f
3
LT5568-2
TYPICAL PERFOR A CE CHARACTERISTICS
V
CC
= 5V, EN = High, T
A
= 25°C, f
LO
= 900MHz,
P
LO
= 0dBm. BBPI, BBMI, BBPQ, BBMQ inputs 0.54V
DC
, Baseband Input Frequency f
BB
= 2MHz, I&Q 90° shifted. 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
0
85°C
–2
RF OUTPUT POWER (dBm)
SUPPLY CURRENT (mA)
VOLTAGE GAIN (dB)
25°C
–4
–6
–8
–10
–12
90
4.5
–14
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)
55682 G02
–6
–8
–10
–12
–14
–16
–18
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)
55682 G03
–4
Supply Current vs Supply Voltage
120
110
100
–40°C
5
SUPPLY VOLTAGE (V)
Output IP3 vs LO Frequency
26
24
22
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)
60
f
BB, 1
= 2MHz
f
BB, 2
= 2.1MHz
70
OP1dB (dBm)
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)
55682 G05
OIP3 (dBm)
OIP2 (dBm)
LO Feedthrough to RF Output
vs LO Frequency
–38
–45
LO FEEDTHROUGH (dBm)
–40
P(2 • LO) (dBm)
P(3 • LO) (dBm)
–42
–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)
55682 G07
–46
550
4
U W
Voltage Gain vs LO Frequency
5.5
55682 G01
Output IP2 vs LO Frequency
10
f
IM2
= f
BB, 1
+ f
BB, 2
+ f
LO
f
BB, 1
= 2MHz
f
BB, 2
= 2.1MHz
8
Output 1dB Compression
vs LO Frequency
65
6
55
4
50
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)
55682 G06
45
550
2
550
55682 G04
2 • LO Leakage to RF Output
vs 2 • LO Frequency
–45
3 • LO Leakage to RF Output
vs 3 • LO Frequency
–50
–50
–55
–55
–60
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
–60
–65
1.1
1.3
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
1.5 1.7 1.9 2.1 2.3
2 • LO FREQUENCY (GHz)
2.5
55682 G08
–65
–70
1.65 1.95 2.25 2.55 2.85 3.15 3.45 3.75
3 • LO FREQUENCY (GHz)
55682 G09
55682f
LT5568-2
TYPICAL PERFOR A CE CHARACTERISTICS
V
CC
= 5V, EN = High, T
A
= 25°C, f
LO
= 900MHz,
P
LO
= 0dBm. BBPI, BBMI, BBPQ, BBMQ inputs 0.54V
DC
, Baseband Input Frequency f
BB
= 2MHz, I&Q 90° shifted. 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 RF Frequency
0
LO PORT, EN = LOW
Noise Floor vs RF Frequency
–158
f
LO
= 900MHz
(FIXED)
NO RF
IMAGE REJECTION (dBc)
–30
–159
NOISE FLOOR (dBm/Hz)
S
11
(dB)
–160
–161
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)
–163
–163
550
LO Feedthrough to RF Output
vs LO Input Power
–38
–40
LO FEEDTHROUGH (dBm)
IMAGE REJECTION (dBc)
–40
–42
–44
–46
– 48
–50
–20
–35
VOLTAGE GAIN (dB)
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
55682 G13
Output IP3 vs LO Power
25
23
HD2 (dBc), HD3 (dBc)
21
0IP3 (dBm)
19
17
15
13
–20
–10
f
BB, 1
= 2MHz
f
BB, 2
= 2.1MHz
–20
85°C
–40°C
HD3
85°C
25°C
–40
–50
–60
–20
25°C
–40°C –30
–40
HD2 (dBc), HD3 (dBc)
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
55682 G16
U W
55682 G10
Image Rejection vs LO Frequency
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
–35
–10
LO PORT, EN = HIGH,
P
LO
= 0dBm
–40
–20
–45
RF PORT,
EN = LOW
RF PORT,
EN = HIGH,
P
LO
= 0dBm
RF PORT, EN = HIGH, No LO
–50
f
BB
= 100kHz
–55
550 650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
55682 G11
–30
LO PORT,
EN = HIGH,
P
LO
= 10dBm
650
–40
550
750 850 950 1050 1150 1250
RF FREQUENCY (MHz)
55682 G12
Image Rejection vs LO Input Power
–4
P
RF
= –10dBm
f
BB
= 100kHz
–6
–8
–10
–12
–14
Voltage Gain vs LO Power
–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
55682 G14
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
55682 G15
–55
–20
–16
–20
RF CW Output Power, HD2 and
HD3 vs CW Baseband Voltage
and Temperature
10
RF
0
–40°C
–30
25°C
–10
–20
–30
–40
–50
–60
–70
–80
RF CW OUTPUT POWER (dBm)
–10
RF CW Output Power, HD2 and
HD3 vs CW Baseband Voltage
and Supply Voltage
10
RF
0
5V
HD3
5V
5.5V
HD2
4.5V
–10
–20
–30
RF CW OUTPUT POWER (dBm)
HD2
85°C
4.5V –40
–50
–60
–70
–80
–50
–60
1
2
3
4
5
I AND Q BASEBAND VOLTAGE (V
P–P, DIFF
)
HD2 = MAX POWER AT f
LO
+ 2 • f
BB
OR f
LO
– 2 • f
BB
HD3 = MAX POWER AT f
LO
+ 3 • f
BB
OR f
LO
– 3 • f
BB
0
0
5
1
2
3
4
I AND Q BASEBAND VOLTAGE (V
P–P, DIFF
)
55682 G18
55682 G17
HD2 = MAX POWER AT f
LO
+ 2 • f
BB
OR f
LO
– 2 • f
BB
HD3 = MAX POWER AT f
LO
+ 3 • f
BB
OR f
LO
– 3 • f
BB
55682f
5
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