LT5506
40MHz to 500MHz
Quadrature Demodulator
with VGA
DESCRIPTIO
The LT
®
5506 is a 40MHz to 500MHz monolithic integrated
quadrature demodulator with variable gain amplifier (VGA),
designed for low voltage operation. It supports standards
that use a linear modulation format. The chip consists of
a VGA, quadrature down-converting mixers and lowpass
noise filters. The LO port consists of a divide-by-two stage
and LO buffers. The IC provides all building blocks for IF
down-conversion to I and Q baseband signals with a single
supply voltage of 1.8V to 5.25V. The VGA gain has a linear-
in-dB relationship to the control input voltage. Hard-clip-
ping amplifiers at the mixer outputs reduce the recovery
time from a signal overload condition. The lowpass filters
reduce the out-of-band noise and spurious frequency
components. The cut-off frequency of the noise filters is
approximately 8.8MHz. The external 2xLO frequency is
required to be twice the IF input frequency for the mixers.
The standby mode provides reduced supply current and
fast transient response into the normal operating mode
when the I/Q outputs are AC-coupled to a baseband chip.
, LTC and LT are registered trademarks of Linear Technology Corporation.
FEATURES
s
s
s
s
s
s
s
s
s
s
s
s
s
s
Wide Range 1.8V to 5.25V Supply
Frequency Range: 40MHz to 500MHz
–4dB to 59dB Variable Power Gain
THD < 0.12% (–58dBc)
at 800mV
P-P
Differential Output Level
8.8MHz I/Q Lowpass Output Noise Filters
IF Overload Detector
Baseband I/Q Amplitude Imbalance: 0.2dB
Baseband I/Q Phase Imbalance: 0.6°
6.8dB Noise Figure at Max Gain
Input IP3 at Low Gain: – 0.5dBm
Low Supply Current: 27mA
Low Delay Shift Over Gain Control Range: 2ps/dB
Outputs Biased Up While in Standby
16-Lead QFN 4mm x 4mm Package with Exposed Pad
APPLICATIO S
s
s
s
IEEE802.11
High Speed Wireless LAN
Wireless Local Loop
TYPICAL APPLICATIO
280MHz
IF INPUT
L1
15nH
C3
10pF
L2
15nH
IF
+
C2
1µF
C1
1nF
V
CC
1.8V
–30
–35
I
OUT+
I
OUT–
THD (dBc)
IF
–
–40
–45
–50
–55
–60
–60
GAIN CONTROL
2xLO
C4
560MHz
3.3pF
INPUT
V
CTRL
2xLO
L3
39nH
2xLO
–
EN
STBY
GND
+
IF DET
Q
OUT+
÷2
Q
OUT–
LT5506
5506 TA01
C3
1.8pF
C5
3.3pF
ENABLE STANDBY
U
U
U
Total Harmonic Distortion vs
IF Input Level at 1.8V Supply
f
IF, 1
= 280MHz
f
IF, 2
= 280.1MHz
f
2xLO
= 570MHz
800mV
P-P
DIFFERENTIAL OUT
–40
–30
–20
–50
IF INPUT POWER EACH TONE (dBm)
–10
5506 TA01b
5506fa
1
LT5506
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
Supply Voltage ....................................................... 5.5V
Differential Voltage Between 2xLO
+
and 2xLO
–
.......... 4V
IF
+
, IF
–
............................................. –500mV to 500mV
I
OUT+
, I
OUT–
, Q
OUT+
, Q
OUT–
.................. V
CC
– 1.8V to V
CC
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
Q
OUT+
16 15 14 13
GND 1
IF
+
Q
OUT–
I
OUT+
I
OUT–
ORDER PART
NUMBER
12 STBY
LT5506EUF
2
3
IF
–
17
11 2xLO
+
10 2xLO
–
9
EN
GND 4
5
6
7
8
IF DET
V
CC
UF PACKAGE
16-LEAD (4mm
×
4mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 37°C/W
EXPOSED PAD (PIN 17) IS GROUND
MUST BE SOLDERED TO PCB
Consult LTC Marketing for parts specified with wider operating temperature ranges.
V
CC
= 3V. f
2xLO
= 570MHz, P
2xLO
= –5dBm (Note 5), f
IF
= 284MHz,
P
IF
= –30dBm, I and Q outputs 800mV
P-P
into 4kΩ differential load, T
A
= 25°C, EN = V
CC
, STBY = V
CC
, unless otherwise noted. (Note 3)
SYMBOL
IF Input
f
IF
Frequency Range
Nominal Input Level
Input Impedance
NF
G
L
G
H
IIP3
IIP2
Noise Figure at Max Gain
Min Gain (Note 4)
Max Gain (Note 4)
Input IP3, Min Gain
Input IP3, Max Gain
Input IP2, Max Gain
Nominal Voltage Swing
Clipping Level
DC Common Mode Voltage
I/Q Amplitude Imbalance
I/Q Phase Imbalance
DC Offset
Output Driving Capability
STBY to Turn-On Delay
I/Q Output 1dB Compression
I/Q Output IM3
P
IF, 1
= –25.5dBm, 280MHz
P
IF, 2
= –25.5dBm, 280.1MHz (Note 7)
(Note 8)
(Note 8)
(Notes 6, 8)
Single Ended, C
LOAD
≤
10pF
2
Demodulator I/Q Output
(Note 6)
(Note 6)
0.8
1.25
V
CC
– 1.19
0.2
0.6
28
1.5
0.3
–11.5
– 50
0.5
3
V
P-P
V
P-P
V
dB
Deg
mV
kΩ
µs
dBm
dBc
R
SOURCE
= 200Ω Differential
IF
+
, IF
–
to GND, EN = V
CC
IF
+
, IF
–
to GND, EN = GND
V
CTRL
= 1.7V
V
CTRL
= 0.2V
V
CTRL
= 1.7V
P
IF
= –22.5dBm (Note 7)
P
IF
= –75dBm (Note 7)
V
CTRL
= 1.7V
50
40 to 500
–79 to –22
100Ω//1.2pF
1pF
6.8
0.9
59
–0.5
–49
–8
8
dB
dB
dB
dBm
dBm
dBm
MHz
dBm
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
ELECTRICAL CHARACTERISTICS
V
CTRL
V
CC
5506fa
2
U
W
U
U
W W
W
LT5506
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
Gain Slope Linearity Error
Temperature Gain Shift
Gain Control Response Time
Gain Control Voltage Range
Gain Control Slope
Gain Control Input Impedance
Delay Shift Over Gain Control
Baseband Lowpass Filter
–3dB Cutoff Frequency
Group Delay Ripple
2xLO Input
f
2xLO
P
2xLO
Frequency Range
Input Power
Input Power
Input Impedance
DC Common Mode Voltage
IF Detector
IF Detector Range
Output Voltage Range
Detector Response Time
Power Supply
V
CC
I
CC
I
OFF
I
STBY
Mode
Enable
Disable
Standby
No Standby
Enable Pin Voltage
Enable Pin Voltage
Standby Pin Voltage
Standby Pin Voltage
EN = High
EN = Low
STBY = High
STBY = Low
1
0.5
1
0.5
V
V
V
V
Supply Voltage
Supply Current
Shutdown Current
Standby Current
EN = High, STBY = Low or High
EN, STBY < 350mV
EN = Low; STBY = High
1.8
26.5
0.2
3.6
5.25
36
30
5.5
V
mA
µA
mA
Referred to IF Input
For P
IF
= –30dBm to 8dBm
With External 1.8pF Load,
Settling within 10% of Final Value
–30 to 8
0.3 to 1.2
100
dBm
V
ns
1:2 Transformer with 240Ω Shunt Resistor (Note 5)
LC Balun (Note 5)
Differential Between 2xLO
+
and 2xLO
–
–20
80 to 1000
–5
–10
800Ω//0.4pF
V
CC
– 0.4
V
MHz
dBm
dBm
7.2
8.8
5
10.4
MHz
ns
To Internal 0.2V
Measured Over 10dB Step
Variable Gain Amplifier (VGA)
V
CTRL
= 0V to 1.4V
T = –40°C to 85°C, V
CTRL
= 0V to 1.4V
Settled within 10% of Final Value
±0.5
±0.3
100
0 to 1.7
43
25
2
dB
dB
ns
V
dB/V
kΩ
ps/dB
V
CC
= 3V. f
2×LO
= 570MHz, P
2×LO
= –5dBm (Note 5), f
IF
= 284MHz,
P
IF
= –30dBm, I and Q outputs 800mV
P-P
into 4kΩ differential load, T
A
= 25°C, EN = V
CC
, STBY = V
CC
, unless otherwise noted. (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:
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 6. The
IF input transformer loss is substracted from the measured values.
Note 4:
Power gain is defined here as the I (or Q) output power into a 4kΩ
differential load, divided by the IF input power in dB. To calculate the
voltage gain between the differential I output (or Q output) and the IF
input, including ideal matching network, 10 • log(4kΩ/50) = 19dB has to
be added to this power gain.
Note 5:
If a narrow-band match is used in the 2xLO path instead of a 1:2
transformer with 240Ω shunt resistor, 2xLO input power can be reduced
to –10dBm, without degrading the phase imbalance. See Figure 11 and
Figure 6.
Note 6:
Differential between I
OUT+
and I
OUT–
(or differential between
Q
OUT+
and Q
OUT–
).
Note 7:
The gain control voltage V
CTRL
is set in such a way that the
differential output voltage between I
OUT+
and I
OUT–
(or differential between
Q
OUT+
and Q
OUT–
) is 800mV
P-P
, with the given input power P
IF
.
Note 8:
The typical parameter is defined as the mean of the absolute
values of the data distribution.
5506fa
3
LT5506
V
CC
= 3V. f
2×LO
= 570MHz, P
2×LO
= –5dBm
(Note 5), f
IF
= 284MHz, P
IF
= –30dBm, I and Q outputs 800mV
P-P
into 4kΩ differential load, T
A
= 25°C, EN = V
CC
, STBY = V
CC
,
unless otherwise noted. (Note 3)
Gain and Noise Figure
Supply Current vs Supply Voltage
vs Control Voltage at 3V Supply
32
30
85°C
TYPICAL PERFOR A CE CHARACTERISTICS
SUPPLY CURRENT (mA)
28
26
24
22
G, NF (dB)
25°C
–40°C
20
1.75 2.25 2.75 3.25 3.75 4.25 4.75 5.25
SUPPLY VOLTAGE (V)
5506 G01
Gain and Noise Figure
vs Control Voltage at 1.8V Supply
60
50
40
G, NF (dB)
30
20
NF
10
GAIN
0
–10
0
0.3
0.6
0.9
V
CTRL
(V)
5506 G03
GAIN DEVIATIN FROM LINEAR FIT (dB)
Gain and Noise Figure
vs Control Voltage and V
CC
60
50
40
G, NF (dB)
30
20
NF
10
GAIN
0
–10
0
0.3
0.6
0.9
V
CTRL
(V)
5506 G05
G, NF (dB)
4
U W
1.2
1.2
60
50
40
30
20
NF
10
GAIN
0
–10
0
0.3
0.6
0.9
V
CTRL
(V)
5506 G02
f
IF
= 284MHz
f
2xLO
= 570MHz
1.2
1.5
1.8
GAIN AT 25°C
NF AT 25°C
GAIN AT –40°C
NF AT –40°C
GAIN AT 85°C
NF AT 85°C
Gain Flatness
vs Control Voltage at 1.8V Supply
0.5
0.4
0.3
0.2
0.1
0
–0.1
–0.2
–0.3
–0.4
–0.5
0
0.3
0.9
0.6
V
CTRL
(V)
1.2
1.5
5506 G04
25°C
85°C
f
IF
= 284MHz
f
2xLO
= 570MHz
1.5
1.8
GAIN AT –40°C
NF AT –40°C
GAIN AT 25°C
NF AT 25°C
GAIN AT 85°C
NF AT 85°C
–40°C
Gain and Noise Figure
vs IF Frequency
60
GAIN, V
CTRL
= 1.6V
50
NF, V
CTRL
= 0.2V
40
GAIN, V
CTRL
= 0.9V
30
20
10
0
–10
10
100
IF FREQUENCY (MHz)
1000
5506 G06
NF, V
CTRL
= 0.9V
NF, V
CTRL
= 1.6V
f
IF
= 284MHz
f
2xLO
= 570MHz
1.5
1.8
GAIN AT 1.8V
NF AT 1.8V
GAIN AT 3V
NF AT 3V
GAIN AT 5.25V
NF AT 5.25V
GAIN, V
CTRL
= 0.2V
5506fa
LT5506
V
CC
= 3V. f
2×LO
= 570MHz, P
2×LO
= –5dBm
(Note 5), f
IF
= 284MHz, P
IF
= –30dBm, I and Q outputs 800mV
P-P
into 4kΩ differential load, T
A
= 25°C, EN = V
CC
, STBY = V
CC
,
unless otherwise noted. (Note 3)
Total Harmonic Distortion
vs IF Input Power at 3V Supply
and 800mV
P-P
Differential Out
–30
–35
–40
f
IF,1
= 280MHz
f
IF,2
= 280.1MHz
f
2xLO
= 570MHz
–30
–35
–40
TYPICAL PERFOR A CE CHARACTERISTICS
Total Harmonic Distortion
vs IF Input Power and IF
Frequency
800mV
P-P
DIFFERENTIAL OUT
3V SUPPLY
THD (dBc)
THD (dBc)
–45
–50
–55
–60
–65
–60
–40°C
–45
–50
THD (dBc)
25°C
–55
85°C
–20
–30
IF INPUT POWER EACH TONE (dBm)
5506 G07
–50
–40
Total Harmonic Distortion vs IF
Input Power and Supply Voltage
–30
–35
–40
–40
800mV
P-P
DIFFERENTIAL OUT
f
IF,1
= 280MHz
f
IF,2
= 280.1MHz
f
2xLO
= 570MHz
–50
MAGNITUDE (dB)
THD (dBc)
THD (dBc)
3V
–45
1.8V
–50
5.25V
–55
–60
–60
–20
–30
IF INPUT POWER EACH TONE (dBm)
5506 G10
–50
–40
LPF Frequency Response
vs Baseband Frequency and
Supply Voltage
0
–5
MAGNITUDE (dB)
IF DET OUTPUT (V)
IF DET OUTPUT (V)
–10
3V
1.8V
5.25V
–15
–20
–25
0
10
15
20
5
BASEBAND FREQUENCY (MHz)
U W
25
5505 G13
Total Harmonic Distortion
vs IF Input Power at 1.8V Supply
and 800mV
P-P
Differential Out
–30
–35
–40
–45
–50
25°C
–55
–60
–60
85°C
–40°C
f
IF,1
= 280MHz
f
IF,2
= 280.1MHz
f
2xLO
= 570MHz
f
IF
= 280MHz
f
IF
= 550MHz
f
IF
= 40MHz
–60
–60
–20
–30
IF INPUT POWER EACH TONE (dBm)
5506 G08
–50
–40
–50
–40
–20
–30
IF INPUT POWER EACH TONE (dBm)
5506 G09
Total Harmonic Distortion
vs IF Input Power at 500mV
P-P
Differential Out
f
IF,1
= 280MHz
f
IF,2
= 280.1MHz
f
2xLO
= 570MHz
LPF Frequency Response
vs Baseband Frequency
and Temperature
0
V
CC
= 3V
–5
–45
–10
25°C
85°C
–40°C
–55
–40°C
–60
25°C
–65
–70
–45
85°C
–15
–20
–40
–35
–30
–25
IF INPUT POWER EACH TONE (dBm)
–20
–25
0
10
15
20
5
BASEBAND FREQUENCY (MHz)
25
5505 G12
5506 G11
IF Detector Output Voltage vs
IF Input CW Power at 3V Supply
1.4
1.2
1.0
0.8
0.6
0.4
0.2
–40
f
IF
= 280MHz
1.4
1.2
1.0
0.8
0.6
0.4
IF Detector Output Voltage vs
IF Input CW Power at 1.8V Supply
f
IF
= 280MHz
–40°C
25°C
85°C
–40°C
25°C
85°C
–30
–20
–10
0
IF INPUT CW POWER (dBm)
10
5506 G14
0.2
–40
–30
–20
–10
0
IF INPUT CW POWER (dBm)
10
5506 G15
5506fa
5
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