LTC5544
8
5544f
pin FuncTions
GND (Pins 1, 8, 9, 11, Exposed Pad Pin 17): Ground.
These pins must be soldered to the RF ground plane on
the circuit board. The exposed pad metal of the package
provides both electrical contact to ground and good thermal
contact to the printed circuit board.
RF (Pin 2): Single-Ended Input for the RF Signal. This pin
is internally connected to the primary side of the RF input
transformer, which has low DC resistance to ground. A
series DC-blocking capacitor should be used to avoid
damage to the integrated transformer when DC voltage
is present at the RF input. The RF input is impedance
matched, as long as the LO input is driven with a 2dBm
±5dB source between 4.2GHz and 5.8GHz.
CT (Pin 3): RF Transformer Secondary Center-Tap. This
pin may require a bypass capacitor to ground. See the
Applications Information section. This pin has an internally
generated bias voltage of 1.2V. It must be DC-isolated
from ground and V
CC
.
SHDN (Pin 4): Shutdown Pin. When the input voltage is
less than 0.3V, the IC is enabled. When the input voltage
is greater than 3V, the IC is disabled. Typical SHDN pin
input current is less than 10μA
. This pin must not be
allowed to float.
V
CC1
(Pin 5) and V
CC2
(Pin 7): Power Supply Pins for the
LO Buffer and Bias Circuits. These pins are internally con-
block DiagraM
nected and must be externally connected to a regulated
3.3V supply, with bypass capacitors located close to the
pins. Typical current consumption is 96mA.
LOBIAS (Pin 6): This Pin Allows Adjustment of the LO
Buffer Current. Typical DC voltage is 2.2V.
LO (Pin 10): Single-Ended Input for the Local Oscillator.
This pin is internally connected to the primary side of the
RF input transformer, which has low DC resistance to
ground. A series DC blocking capacitor must be used to
avoid damage to the integrated transformer if DC voltage
is present at the LO input.
TEMP (Pin 12): Temperature Sensing Diode. This pin is
connected to the anode of a diode that may be used to
measure the die temperature, by forcing a current and
measuring the voltage.
IFGND (Pin 13): DC Ground Return for the IF Amplifier.
This pin must be connected to ground to complete the IF
amplifier’s DC current path. Typical DC current is 98mA.
IF
–
(Pin 14) and IF
+
(Pin 15): Open-Collector Differential
Outputs for the IF Amplifier. These pins must be connected
to a DC supply through impedance matching inductors, or
a transformer center-tap. Typical DC current consumption
is 49mA into each pin.
IFBIAS (Pin 16): This Pin Allows Adjustment of the IF
Amplifier Current. Typical DC voltage is 2.1V.
RF
CT
SHDN
PASSIVE
MIXER
V
CC1
V
CC2
GND PINS ARE NOT SHOWN
LO
LOBIAS
TEMP
IF
+
IFBIAS IF
–
IFGND
EXPOSED
PAD
5544 BD
IF
AMP
13
12
10
141516
5
4
2
3
7
6
17
LO
AMP
BIAS
