Final Electrical Specifications
LT5503
1.2GHz to 2.7GHz Direct
IQ Modulator and Mixer
FEATURES
s
s
DESCRIPTIO
October 2001
s
s
s
s
s
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
The LT
®
5503 is a front-end transmitter IC designed for low
voltage operation, and is compatible with the LTC family of
WLAN products. 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 delivers –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
s
s
s
s
s
IEEE 802.11 DSSS and FHSS
High Speed Wireless LAN (WLAN)
Wireless Local Loop (WLL)
PCS Wireless Data
MMDS
, LTC and LT are registered trademarks of Linear Technology Corporation.
*Patent Pending
TYPICAL APPLICATIO
2.45GHz
BPF
V
CC2
2V
V
CC1
2V
–2
V
CC
LO2 V
CC
LO1
MIXER
ENABLE
MODULATOR
ENABLE
LO2IN
(750MHz)
MIXEN
MODEN
LO2
÷2
MX
–
MX
+
MODIN V
CC
RF
V
CC
MOD
V
CC
VGA
OUTPUT POWER (dBm)
BQ
+
BQ
–
0°
÷1
90°
MODOUT
VGA
CONTROL
LOGIC
GND
DMODE
LO1
LO1IN (2075MHz)
BI
+
GC1 GC2
5503 F01
BI
–
2.45GHz
MODULATED
RFOUT
Figure 1. 2.45GHz Transmitter Application, Carrier for Modulator Generated by Upmixer
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
U
–3
–4
–5
–6
1.8
2.4
U
U
2.45GHz Modulated Output
Power vs Supply Voltage
P
LO1
= –12dBm
P
LO2
= –18dBm
BASEBAND = 1V
P-P
T
A
= 27°C
3.0
3.6
4.2
SUPPLY VOLTAGE (V)
4.8
5.4
5503 TA01b
1
LT5503
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
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
FE PACKAGE
20-LEAD PLASTIC TSSOP
PIN 21 = GND (BACKSIDE)
20 BI
–
19 BI
+
18 GC2
17 MODOUT
16 V
CC
VGA
15 V
CC
LO2
14 LO2
13 MODEN
12 MIXEN
11 MX
–
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
ORDER PART
NUMBER
LT5503EFE
T
JMAX
= 150°C,
θ
JA
= 38°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
2
U
W
U
U
W W
W
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
= 27ºC, 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
MIN
TYP
1.2 to 2.7
Z
O
= 50Ω
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
25
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
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
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
Z
O
= 50Ω
–30dBm/Tone,
∆f
= 200kHz
1400 to 2400
1.5:1
–12
dBm
MHz
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
= 27ºC, 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:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
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.
4
LT5503
(I/Q Modulator)
V
CC1
= 3VDC, 2.4GHz matching, MODEN = high, GC1 = GC2 = low (max gain), T
A
= 27°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
= 27°C
T
A
= –40°C
4.6
2.5
3.9
3.2
V
CC1
SUPPLY VOLTAGE (V)
SSB Output Power vs
I, Q Amplitude
0
5.25 VDC
–5
SSB OUTPUT POWER (dBm)
3 VDC
1.8 VDC
OUTPUT POWER (dBm)
–10
–15
–20
–25
–30
–35
–40
–45
0.1
10
0.01
1
I, Q DIFFERENTIAL INPUT VOLTAGE (V
P-P
)
5503 G04
–15
–20
–25
–30
–35
–40
0.1
CARRIER
IMAGE
1
I, Q INPUT FREQUENCY (MHz)
10
5503 G05
RETURN LOSS (dB)
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
= 27°C
1
T
A
= 27°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
–5
–10
DESIRED
SIDEBAND
–10
0
MODRFIN and MODRFOUT
Return Loss 2.4GHz Matching
MODRFOUT
–20
–30
MODRFIN
–40
2050
2250
2450
2650
FREQUENCY (MHz)
2850
5503 G06
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
5
嵌入式系统
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