LT5503
1.2GHz to 2.7GHz Direct
IQ Modulator and Mixer
FEATURES
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DESCRIPTIO
Single 1.8V to 5.25V Supply
Direct IQ Modulator with Integrated 90° Phase
Shifter*
Four Step RF Power Control
120MHz Modulation Bandwidth
Independent Double-Balanced Mixer
Modulation Accuracy Insensitive to Carrier Input
Power
Modulator I/Q Inputs Internally Biased
Available in 20-Lead FE Package
The LT
®
5503 is a front-end transmitter IC designed for low
voltage operation. The IC contains a high frequency quadra-
ture modulator with a variable gain amplifier (VGA) and a
balanced mixer. The modulator includes a precision 90°
phase shifter which allows direct modulation of an RF
signal by the baseband I and Q signals.
In a superheterodyne system, the mixer can be used to
generate the high-frequency RF input for the modulator by
mixing the system’s 1st and 2nd local oscillators.
The LT5503 modulator output P 1dB is –3dBm at 2.5GHz.
The VGA allows output power reduction in three steps up
to 13dB with digital control. The baseband inputs are
internally biased for maximum input voltage swing at low
supply voltage. If needed, they can be driven with external
bias voltages.
APPLICATIO S
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IEEE 802.11 DSSS and FHSS
High Speed Wireless LAN (WLAN)
Wireless Local Loop (WLL)
PCS Wireless Data
MMDS
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. *Patent Pending
TYPICAL APPLICATIO
2.45GHz Transmitter Application, Carrier for Modulator Generated by Upmixer
2.45GHz
BPF
V
CC2
2V
V
CC1
2V
SSB OUTPUT POWER (dBm)
BQ
+
BQ
–
V
CC
LO2 V
CC
LO1
MIXER
ENABLE
MODULATOR
ENABLE
LO2IN
(750MHz)
MIXEN
MODEN
LO2
÷2
0°
÷1
90°
MODOUT
VGA
MX
–
MX
+
MODIN V
CC
RF
V
CC
MOD
V
CC
VGA
LT5503
GND
DMODE
LO1
LO1IN (2075MHz)
CONTROL
LOGIC
GC1 GC2
5503 TA01
BI
+
BI
–
2.45GHz
MODULATED
RFOUT
U
SSB Output Power vs
I, Q Amplitude
0
5.25 VDC
–5
–10
–15
–20
–25
–30
–35
–40
–45
0.1
10
0.01
1
I, Q DIFFERENTIAL INPUT VOLTAGE (V
P-P
)
5503 G04
U
U
3 VDC
1.8 VDC
5503f
1
LT5503
ABSOLUTE
(Note 1)
AXI U RATI GS
PI CO FIGURATIO
TOP VIEW
BQ
–
1
BQ
+
2
GC1 3
MODIN 4
V
CC
MOD 5
V
CC
RF 6
LO1 7
V
CC
LO1 8
DMODE 9
MX
+
10
21
Supply Voltage ...................................................... 5.5V
Control Voltages .......................... –0.3V to (V
CC
+ 0.3V)
Baseband Voltages (BI
+
to BI
–
and BQ
+
to BQ
–
) ......
±2V
Baseband Common Mode Voltage .....1V to (V
CC
– 0.3V)
LO1 Input Power .................................................. 4dBm
LO2 Input Power .................................................. 4dBm
MODIN Input Power ............................................. 4dBm
Operating Temperature Range .................–40°C to 85°C
Storage Temperature Range ..................–65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
FE PACKAGE
20-LEAD PLASTIC TSSOP
T
JMAX
= 150°C,
θ
JA
= 38°C/W
EXPOSED PAD IS GND (PIN 21)
MUST BE SOLDERED TO PCB
ORDER I FOR ATIO
LEAD FREE FINISH
LT5503EFE#PBF
TAPE AND REEL
LT5503EFE#TRPBF
PART MARKING
5503
PACKAGE DESCRIPTION
20-Lead Plastic TSSOP
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/
2
U
20 BI
–
19 BI
+
18 GC2
17 MODOUT
16 V
CC
VGA
15 V
CC
LO2
14 LO2
13 MODEN
12 MIXEN
11 MX
–
U
U
U
U
W W
W
W
U
TEMPERATURE RANGE
–40°C to 85°C
5503f
LT5503
ELECTRICAL CHARACTERISTICS
PARAMETER
RF Carrier Input (MODRFIN)
Frequency Range
2
Input VSWR
Input Power
Baseband Inputs (BI
+
, BI
–
, BQ
+
, BQ
–
)
Frequency Bandwidth (3dB)
Differential Input Voltage for 1dB Compressed Output
DC Common-Mode Voltage
Differential Input Resistance
Input Capacitance
Gain Error
Phase Error
Modulated RF Carrier Output (MODRFOUT)
Output Power, Max Gain
Output VSWR
Image Suppression
Carrier Suppression
Output 1dB Compression
Output 3rd Order Intercept
Output 2rd Order Intercept
Broadband Noise
VGA Control Logic (GC2, GC1)
Switching Time
Input Current
Input Low Voltage
Input High Voltage
Output Power Attenuation
Output Power Attenuation
Output Power Attenuation
Modulator Enable (MODEN)
Low = Off, High = On
Turn ON/OFF Time
Input Current
Enable
Disable
Modulator Power Supply Requirements
Supply Voltage
Modulator Supply Current
Modulator Shutdown Current
(I/Q Modulator)
V
CC1
= 3VDC, 2.4GHz matching, MODEN = High, GC1 = GC2 = Low, T
A
= 25°C, MODRFIN = 2.45GHz at –16dBm, [I – I
B
] and [Q – Q
B
] =
100kHz CW signal at 1V
P-P
differential, Q leads I by 90°, unless otherwise noted. (Test circuit shown in Figure 2.) (Note 3)
CONDITIONS
Requires Appropriate Matching
Z
O
= 50Ω
MIN
TYP
1.2 to 2.7
1.3:1
–20 to -10
120
1
Internally Biased
1.4
18
0.8
±0.2
±1
–6
Z
O
= 50Ω
– 26
– 24
f
I
= 100kHz, f
Q
= 120kHz
f
I
= 100kHz, f
Q
= 120kHz
20MHz Offset
–3
1.5:1
–34
–32
–3
2
16
–142
100
2
0.4
1.7
GC2 = Low, GC1 = High
GC2 = High, GC1 = Low
GC2 = High, GC1 = High
4.5
9
13.5
1
105
V
CC
– 0.4
0.4
1.8
MODEN = High
MODEN = Low
29
5.25
38
50
dBc
dBc
dBm
dBm
dBm
dBm/Hz
ns
μA
VDC
VDC
dB
dB
dB
μs
μA
VDC
VDC
VDC
mA
μA
dBm
MHz
V
P-P
VDC
kΩ
pF
dB
DEG
dBm
MAX
UNITS
GHz
5503f
3
LT5503
ELECTRICAL CHARACTERISTICS
PARAMETER
Mixer 2nd LO Input (LO2IN)
Frequency Range
Input VSWR
Input Power
Mixer 1st LO Input (LO1IN)
Frequency Range
2
Input VSWR
Input 3rd Order Intercept
Mixer RF Output (MIXRFOUT)
Frequency Range
2
Output VSWR
Small-Signal Conversion Gain
Output Power
LO1 Suppression
Output 1dB Compression
Broadband Noise
Input Current
Input Low Voltage (÷2)
Input High Voltage (÷1)
Mixer Enable (MIXEN)
Low = Off, High = On
Turn ON/OFF Time
Input Current
Enable
Disable
Mixer Power Supply Requirements
Supply Voltage
Supply Current (÷2 mode)
Supply Current (÷1 mode)
Shutdown Current
DMODE = Low, MIXEN = High
DMODE = High, MIXEN = High
MIXEN = Low
1.8
11.9
10.8
10
5.25
15.5
VDC
mA
mA
μA
V
CC
– 0.4
0.4
1
130
μs
μA
VDC
VDC
V
CC
– 0.4
20MHz Offset
LO2 Divider Mode Control (DMODE)
Low = f
LO2
÷
2, High = f
LO2
÷
1
1
0.4
μA
VDC
VDC
Requires Appropriate Matching
Z
O
= 50Ω
P
LO1
= –30dBm
–14.7
– 22
1700 to 2700
1.5:1
5
–12.7
– 29
–15
–152
dB
dBm
dBc
dBm
dBm/Hz
MHz
Requires Appropriate Matching
Z
O
= 50Ω
–30dBm/Tone,
Δf
= 200kHz
1400 to 2400
1.5:1
–12
dBm
MHz
Internally Matched
Z
O
= 50Ω
50 to 1000
1.4:1
–20 to –12
dBm
MHz
(Mixer)
V
CC2
= 3VDC, 2.4GHz matching, MIXEN = High, DMODE = Low (LO2
÷
2 mode), T
A
= 25°C, LO2IN = 750MHz at –18dBm, LO1IN =
2075MHz at –12dBm. MIXRFOUT measured at 2450MHz, unless otherwise noted. (Test circuit shown in Figure 2.) (Note 3)
CONDITIONS
MIN
TYP
MAX
UNITS
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:
External component values on the final test circuit shown in
Figure 2 are optimized for operation in the 2.4GHz to 2.5GHz band.
Note 3:
Specifications over the –40°C to 85°C temperature range are
assured by design, characterization and correlation with statistical process
controls.
5503f
4
LT5503
(I/Q Modulator)
V
CC1
= 3VDC, 2.4GHz matching, MODEN = high, GC1 = GC2 = low (max gain), T
A
= 25°C, MODRFIN = 2.45GHz at –16dBm, (I–I
B
) and
(Q–Q
B
) = 100kHz sine at 1V
P-P
differential, Q leads I by 90°, unless otherwise noted. (Test circuit shown in Figure 2.)
Modulator Supply Current vs
Supply Voltage
38
36
SHUTDOWN CURRENT (μA)
SUPPLY CURRENT (mA)
TYPICAL PERFOR A CE CHARACTERISTICS
34
32
30
28
26
24
22
20
1.8
T
A
= 85°C
10
T
A
= 85°C
INPUT CURRENT (μA)
T
A
= 25°C
T
A
= –40°C
4.6
2.5
3.9
3.2
V
CC1
SUPPLY VOLTAGE (V)
2.45GHz Modulated Output
Power vs Supply Voltage
–2
0
–5
OUTPUT POWER (dBm)
OUTPUT POWER (dBm)
–3
–15
–20
–25
–30
–35
–40
0.1
CARRIER
IMAGE
1
I, Q INPUT FREQUENCY (MHz)
10
5503 G05
RETURN LOSS (dB)
–4
–5
P
LO1
= –12dBm
P
LO2
= –18dBm
BASEBAND = 1V
P-P
T
A
= 25°C
1.8
2.4
3.0
3.6
4.2
SUPPLY VOLTAGE (V)
4.8
5.4
–6
P
OUT
(dBm)
U W
5503 G01
Modulator Shutdown Current vs
Supply Voltage
100
MODEN = LOW
220
200
180
MODEN Current vs Enable
Voltage
MODEN = V
CC1
T
A
= 85°C
160
140
120
100
80
60
T
A
= –40°C
T
A
= 25°C
1
T
A
= 25°C
5.3
0.1
1.8
T
A
= –40°C
4.6
2.5
3.9
3.2
V
CC1
SUPPLY VOLTAGE (V)
5.3
5503 G02
40
1.8
2.5
4.6
3.9
3.2
MODEN VOLTAGE (V)
5.3
5503 G03
Baseband Frequency Response
I/Q Amplitude = 1V
P-P
0
DESIRED
SIDEBAND
MODRFIN and MODRFOUT
Return Loss 2.4GHz Matching
–10
–10
MODRFOUT
–20
–30
MODRFIN
–40
2050
2250
2450
2650
FREQUENCY (MHz)
2850
5503 G06
5503 TA01b
Typical SSB Spectrum
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
2449.6 2449.8 2450.0 2450.2 2450.4
FREQUENCY (MHz)
2450.6
5503 G07
5503f
5
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