lt5546 Linear Technology Corporation, lt5546 Datasheet - Page 6

• Manufacturer Part Number: lt5546
• Description: 40mhz To 500mhz Vga And I/q Demodulator With 17mhz Baseband Bandwidth
• Manufacturer: Linear Technology Corporation

PI FU CTIO S
GND (Pins 1, 4 and 17): Ground. Pins 1 and 4 are
connected to each other internally. The exposed pad (Pin
17) is not connected internally to Pins 1 and 4. For chip
functionality, the exposed pad and either Pin 1 or Pin 4
must be connected to ground. For best RF performance,
Pin 1, Pin 4 and the exposed pad should be connected to
RF ground.
IF
Each pin must be DC grounded through an external
inductor or RF transformer with central ground tap. This
path should have a DC resistance lower than 2Ω to ground.
V
decoupled to ground using 1000pF and 0.1µF capacitors.
V
the IF gain and its typical input voltage range is 0.2V to
1.7V. It is internally biased via a 25k resistor to 0.2V,
setting a low gain if the V
IF
signals, the DC level at this pin is a function of the IF input
signal level.
LT5546
(Note 5), f
unless otherwise noted. (Note 3)
TYPICAL PERFOR A CE CHARACTERISTICS
6
CC
CTRL
+
1.4
1.2
1.0
0.8
0.6
0.4
0.2
DET
, IF
U
(Pins 5 and 8): Power Supply. These pins should be
–40
IF Detector Output Voltage
vs IF Input CW Power and
Supply Voltage
f
–
(Pin 6): VGA Gain Control Input. This pin controls
IF
(Pin 7): IF Detector Output. For strong IF input
= 280MHz
(Pins 2, 3): Differential Inputs for the IF Signal.
IF
–30
U
= 284MHz, P
IF INPUT CW POWER (dBm)
–20
U
IF
–10
3V
= –30dBm, I and Q outputs 800mV
CTRL
1.8V
5.25V
W
0
pin is left floating.
5546 G16
U
10
1.4
1.2
1.0
0.8
0.4
0.2
0.6
–40
IF Detector Output Voltage vs IF
Input CW Power and IF Frequency
V
CC
= 3V
–30
IF INPUT CW POWER (dBm)
P-P
into 4kΩ differential load, T
–20
f
IF
EN (Pin 9): Enable Input. When the enable pin voltage is
higher than 1V, the IC is completely turned on. When the
input voltage is less than 0.5V, the IC is turned off, except
the part of the circuit associated with standby mode.
2xLO
2xLO Input. The 2xLO input frequency must be twice that
of the IF frequency. The internal bias voltage is V
STBY (Pin 12): Standby Input. When the STBY pin is
higher than 1V, the standby mode circuit is turned on to
prebias the I/Q buffers. When the STBY pin is less than
0.5V, the standby mode circuit is turned off.
Q
puts of the Q Channel. Internally biased at V
I
of the I Channel. Internally biased at V
= 280MHz
OUT
OUT
–10
f
IF
–
= 500MHz
–
–
, I
, Q
, 2xLO
f
IF
OUT
= 40MHz
0
OUT
+
5546 G17
V
(Pins 15, 16): Differential Baseband Outputs
+
+
CC
10
(Pins 13, 14): Differential Baseband Out-
(Pins 10, 11): Differential Inputs for the
= 3V, f
A
2×LO
= 25°C, EN = V
95
94
93
92
91
90
89
88
–20
= 570MHz, P
Phase Relation Between I and Q
Outputs vs LO Input Power
V
CC
–15
= 3V
LO INPUT POWER (dBm)
CC
–10
, STBY = V
2×LO
CC
–5
= –5dBm
– 1.19V.
f
f
f
f
f
IF
IF
IF
IF
IF
CC
= 284MHz, 25°C
= 284MHz, –40°C
= 284MHz, 85°C
= 40MHz, 25°C
= 500MHz, 25°C
CC
0
CC
– 1.19V.
,
– 0.4V.
5
5546 G18
5546fa
10