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LT5502
1
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.
Final Electrical Specifications
s
IEEE802.11
s
High Speed Wireless LAN
s
Wireless Local Loop
s
Single 1.8V to 5.25V Supply
s
IF Frequency Range: 70MHz to 400MHz
s
84dB Limiting IF Gain
s
90dB Linear RSSI Range
s
7.7MHz Lowpass Output Filter
s
Baseband I/Q Amplitude Imbalance: <0.7dB
s
4dB Noise Figure
s
Low Supply Current: 25mA
s
Outputs Biased Up While in Standby
s
Shutdown Current: 1
A
s
24-Lead Narrow SSOP Package
APPLICATIO S
U
FEATURES
DESCRIPTIO
U
TYPICAL APPLICATIO
U
400MHz Quadrature
IF Demodulator with RSSI
January 2001
, LTC and LT are registered trademarks of Linear Technology Corporation.
The LT
5502 is a 70MHz to 400MHz monolithic integrated
quadrature IF demodulator. It consists of an IF limiter,
quadrature down mixers, integrated lowpass filters, and
divide-by-two LO buffers. The demodulator provides all
building blocks for demodulation of I and Q baseband
signals with a single supply voltage of 1.8V to 5.25V. The
IF limiter has 84dB small-signal gain, and a built-in receive
signal strength indicator (RSSI) with over 90dB linear
range. The input referred noise-spectral-density is
1.45nV/
Hz, which is equivalent to a 4dB noise figure
when the input is terminated with a 50
source. The
integrated lowpass output filters act as antialiasing and
pulse-shaping filters for demodulated I/Q-baseband sig-
nals. The 3dB cutoff frequency of the filters is about
7.7MHz. The VCO frequency is required to be twice the
desired operating frequency to provide quadrature local
oscillator (LO) signals to the mixers. The standby mode
provides fast transient response to the receive mode with
reduced supply current when the I/Q outputs are
AC-coupled to a baseband chip.
I/Q Output Swing, RSSI Output vs IF Input Power
IF INPUT POWER (dBm)
85
DIFFERENTIAL OUTPUT SWING (mV
P-P
)
1200
1000
800
600
400
200
RSSI OUTPUT (V)
1.2
1.0
0.8
0.6
0.4
0.2
70
55
40
25
5502 TA01b
10
5
2XLO
+
2XLO
IF
+
IF
EN
V
CC
I
OUT
+
I
OUT
Q
OUT
+
Q
OUT
90
0
GND
2V
C2
1
F
C1
1nF
C4
1.8pF
RSSI
ENABLE
2XLO
INPUT
IF
INPUT
R1
240
C3
22nF
BASEBAND
DIFFERENTIAL
I/Q OUTPUTS
5502 TA01a
2
LT5502
LT5502
2
Power Supply Voltage ............................................ 5.5V
LO Input Power .................................................. 10dBm
IF Input Power .................................................... 10dBm
Operating Ambient
Temperature (Note 2) ..............................40
C to 85
C
Storage Temperature Range ................. 65
C to 150
C
Lead Temperature (Soldering, 10 sec).................. 300
C
Voltage on any Pin not to Exceed ............................. V
CC
ORDER PART
NUMBER
T
JMAX
= 150
C,
JA
= 85
C/W
LT5502EGN
ABSOLUTE AXI U
RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
(Note 1)
ELECTRICAL CHARACTERISTICS
V
CC
= 3V, f
2XLO
= 570MHz, P
2XLO
= 10dBm, f
IF
= 280MHz,
P
IF
= 50dBm, T
A
= 25
C, unless otherwise noted. (Note 3)
Consult factory for parts specified with wider operating temperature ranges.
1
2
3
4
5
6
7
8
9
10
11
12
TOP VIEW
GN PACKAGE
24-LEAD NARROW PLASTIC SSOP
24
23
22
21
20
19
18
17
16
15
14
13
Q
OUT
+
Q
OUT
V
CC
GND
GND
2XLO
+
2XLO
V
CC
V
CC
RSSI
GND
IFt
I
OUT
+
I
OUT
GND
V
CC
GND
IF
+
IF
GND
GND
EN
STBY
IFt
+
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
IF Input
f
IF
Frequency Range
70 to 400
MHz
3dB Limiting Sensitivity
79
dBm
Noise Figure
Terminated 50
Source
4
dB
DC Common Mode Voltage
2.6
V
Demodulator I/Q Output
I/Q Output Voltage Swing
Differential
850
mV
P-P
I/Q Amplitude Mismatch
0.1
0.7
dB
I/Q Phase Mismatch
0.6
DEG
Output Driving Capability
Differential; C
MAX
= 10pF
1.5
k
DC Common Mode Voltage
1.84
V
RSSI
Linear Dynamic Range (Note 4)
3dB Linearity Error
90
dB
Output Impedance
3.8
k
Output Voltage
Input = 70dBm
0.27
0.41
0.54
V
Output Voltage
Input = 0dBm
0.8
1.01
1.2
V
Output Voltage Slope
Input from 70dBm to 0dBm
8.7
mV/dB
Linearity Error
Input from 70dBm to 0dBm
1
dB
Baseband Lowpass Filter
3dB Cutoff Frequency
7.7
MHz
Group Delay Ripple
16.4
ns
LT5502
3
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Power Supply Current
vs Temperature
I/Q Output Swing vs Temperature
I/Q Output Swing vs IF Input Power
ELECTRICAL CHARACTERISTICS
V
CC
= 3V, f
2XLO
= 570MHz, P
2XLO
= 10dBm, f
IF
= 280MHz,
P
IF
= 50dBm, T
A
= 25
C, unless otherwise noted. (Note 3)
(Note 3)
IF INPUT POWER (dBm)
85
DIFFERENTIAL OUTPUT SWING (mV
P-P
)
5
5502 G03
70
55
40
25
10
1200
1000
800
600
400
200
T
A
= 40
C
T
A
= 25
C
T
A
= 85
C
V
CC
= 3V
f
IF
= 280MHz
SUPPLY VOLTAGE (V)
1.8
SUPPLY CURRENT (mA)
5.5
5502 G01
2.5
3.5
4.5
36
32
28
24
20
16
T
A
= 40
C
T
A
= 25
C
T
A
= 85
C
SUPPLY VOLTAGE (V)
1.8
DIFFERENTIAL OUTPUT SWING (mV
P-P
)
800
1000
5.5
5502 G02
600
400
2.5
3.5
4.5
1200
T
A
= 40
C
T
A
= 25
C
T
A
= 85
C
f
IF
= 280MHz
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
2XLO
f
2XLO
Frequency Range
140 to 800
MHz
P
2XLO
Input Power
20
5
dBm
DC Common Mode Voltage
2.6
V
Power Supply
V
CC
Supply Voltage
1.8
5.25
V
I
CC
Supply Current
EN = High
25
32
mA
I
OFF
Shutdown Current
EN = Low; Standby = Low
1
100
A
Standby Mode Current
EN = Low; Standby = High
2.6
3.5
mA
Note 1: Absolute Maximum Ratings are those values beyond which the life
a device may be impaired.
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 3.
Note 4: Tests are performed as shown in the configuration of Figure 1 for
IF input.
LT5502
4
RSSI Output Voltage vs V
CC
IF Input Sensitivity
vs Temperature
IF Input Sensitivity vs IF Frequency
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
LPF Frequency Response
vs Baseband Frequency
LPF Group Delay
vs Baseband Frequency
LPF Frequency Response vs V
CC
(Note 3)
IF INPUT POWER (dBm)
85
RSSI OUTPUT (V)
5
5502 G07
70
55
40
25
10
1.2
1.0
0.8
0.6
0.4
0.2
f
IF
= 280MHz
T
A
= 25
C
V
CC
= 3V
V
CC
= 5.5V
V
CC
= 1.8V
SUPPLY VOLTAGE (V)
1.8
INPUT SENSITIVITY (dBm)
5.5
5502 G08
2.5
3.5
4.5
73
75
77
79
81
83
T
A
= 40
C
T
A
= 25
C
T
A
= 85
C
f
IF
= 280MHz
IF FREQUENCY (MHz)
70
INPUT SENSITIVITY (dBm)
79
76
5502 G09
82
85
150
200
250
300
350
400
100
73
T
A
= 40
C
T
A
= 25
C
V
CC
= 3V
T
A
= 85
C
BASEBAND FREQUENCY (MHz)
0
GAIN RESPONSE (dB)
12
20
5502 G10
4
8
16
5
0
5
10
15
20
25
30
35
V
CC
= 3V
T
A
= 85
C
T
A
= 40
C
T
A
= 25
C
BASEBAND FREQUENCY (MHz)
0
GROUP DELAY (ns)
110
95
80
65
50
35
20
4
8
12
16
5502 G11
20
V
CC
= 3V
T
A
= 85
C
T
A
= 40
C
T
A
= 25
C
BASEBAND FREQUENCY (MHz)
0
GAIN RESPONSE (dB)
12
20
5502 G12
4
8
16
5
0
5
10
15
20
25
30
35
110
90
70
50
30
V
CC
= 1.8V, 3V, 5.5V
T
A
= 25
C
GROUP DELAY (ns)
I/Q Output Swing vs IF Input Power
RSSI Output vs Temperature
RSSI Output Voltage vs IF Frequency
IF INPUT POWER (dBm)
85
DIFFERENTIAL OUTPUT SWING (mV
P-P
)
5
5502 G04
70
55
40
25
10
1200
1000
800
600
400
200
f
IF
= 70MHz
f
IF
= 280MHz
f
IF
= 400MHz
V
CC
= 3V
T
A
= 25
C
IF INPUT POWER (dBm)
85
RSSI OUTPUT (V)
5
5502 G05
70
55
40
25
10
1.2
1.0
0.8
0.6
0.4
0.2
T
A
= 40
C
T
A
= 85
C
V
CC
= 3V
f
IF
= 280MHz
T
A
= 25
C
IF INPUT POWER (dBm)
85
RSSI OUTPUT (V)
5
5502 G06
70
55
40
25
10
1.2
1.0
0.8
0.6
0.4
0.2
f
IF
= 70MHz
f
IF
= 280MHz
V
CC
= 3V
T
A
= 25
C
f
IF
= 400MHz
LT5502
5
U
U
U
PI FU CTIO S
I
OUT
+
(Pin 1): Positive Baseband Output Pin of I-Channel.
The DC bias voltage is V
CC
1.16V. This pin should not be
shorted to ground.
I
OUT
(Pin 2): Negative Baseband Input Pin of I-Channel.
The DC bias voltage is V
CC
1.16V. This pin should not be
shorted to ground.
GND (Pins 3, 5, 8, 9, 14, 20, 21): Ground Pin.
V
CC
(Pins 4, 16, 17, 22): Power Supply Pin. This pin
should be decoupled using 1000pF and 0.1
F capacitors.
IF
+
(Pin 6): Positive IF Input Pin. The DC bias voltage is
V
CC
0.4V.
IF
(Pin 7): Negative IF Input Pin. The DC bias voltage is
V
CC
0.4V.
EN (Pin 10): Enable Pin. When the input voltage is higher
than 0.9V or up to V
CC
, the circuit is completely turned on.
When the input voltage is less than 0.7V or down to
ground, the circuit is turned off except the part of the
circuit associated with standby mode.
STBY (Pin 11): Standby Pin. When the input voltage is
higher than 0.9V or up to V
CC
, the circuit of standby mode
is turned on to bias the I/Q buffers to desired quiescent
voltage. When the input voltage is less than 0.7V or down
to ground, it is turned off.
IFt
+
(Pin 12): Interstage IF Positive Pin. The DC bias
voltage is V
CC
0.25V.
IFt
(Pin 13): Interstage IF Negative Pin. The DC bias
voltage is V
CC
0.25V.
RSSI (Pin 15): RSSI Output Pin.
2XLO
(Pin 18): Negative Carrier Input Pin. The input-
signal's frequency must be twice that of the desired
demodulator LO frequency. The DC bias voltage is V
CC
0.4V.
2XLO
+
(Pin 19): Positive Carrier Input Pin. The input-
signal's frequency must be twice that of the desired
demodulator LO frequency. The DC bias voltage is V
CC
0.4V.
Q
OUT
(Pin 23): Negative Baseband Output Pin of the
Q-Channel. The DC bias voltage is V
CC
1.16V. This pin
should not be shorted to ground.
Q
OUT
+
(Pin 24): Positive Baseband Output Pin of the
Q-Channel. The DC bias voltage is V
CC
1.16V. This pin
should not be shorted to ground.
BLOCK DIAGRA
W
2XLO
+
2XLO
IF
+
IF
EN
BIAS
5502 BD
LIMITER
2
LIMITER
1
1
6
12
13
7
2
24
23
10
15
RSSI
RSSI
LO
BUFFERS
IFt
+
IFt
I
OUT
+
I
OUT
Q
OUT
+
Q
OUT
Q-MIXER
I-MIXER
LPF
LPF
1
1
DIVIDE 2
0
/90
19
18
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