LTC5591
10
5591f
pin FuncTions
RFA, RFB (Pins 1, 6): Single-Ended RF Inputs for Chan-
nels A and B. These pins are internally connected to the
primary sides of the RF input transformers, which have
low DC resistance to ground. Series DC-blocking capaci-
tors should be used to avoid damage to the integrated
transformer when DC voltage is present at the RF inputs.
The RF inputs are impedance matched when the LO input
is driven with a 0±6dBm source between 1.4GHz and
2.1GHz and the channels are enabled.
CTA, CTB (Pins 2, 5): RF Transformer Secondary Center-
Tap on Channels A and B. These pins may require bypass
capacitors to ground to optimize IIP3 performance. Each
pin has an internally generated bias voltage of 1.2V and
must be DC-isolated from ground and V
CC
.
GND (Pins 3, 4, 7, 13, 15, 24, Exposed Pad Pin 25):
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.
IFGNDB, IFGNDA (Pins 8, 23): DC Ground Returns for the
IF Amplifiers. These pins must be connected to ground to
complete the DC current paths for the IF amplifiers. Chip
inductors may be used to tune LO-IF and RF-IF leakage.
Typical DC current is 100mA for each pin.
IFB
+
, IFB
–
, IFA
–
, IFA
+
(Pins 9, 10, 21, 22): Open-Collec-
tor Differential Outputs for the IF Amplifiers of Channels
B and A. These pins must be connected to a DC supply
through impedance matching inductors, or transformer
center-taps. Typical DC current consumption is 50mA
into each pin.
IFBB, IFBA (Pins 11, 20): Bias Adjust Pins for the IF
Amplifiers. These pins allow independent adjustment
of the internal IF buffer currents for channels B and A,
respectively. The typical DC voltage on these pins is 2.2V.
If not used, these pins must be DC isolated from ground
and V
CC
.
V
CCB
and V
CCA
(Pins 12, 19): Power Supply Pins for the
LO Buffers and Bias Circuits. These pins must be con-
nected to a regulated 3.3V supply with bypass capacitors
located close to the pins. Typical current consumption is
91mA per pin.
ENB, ENA (Pins 14, 17): Enable Pins. These pins allow
Channels B and A, respectively, to be independently en-
abled. An applied voltage of greater than 2.5V activates
the associated channel while a voltage of less than 0.3V
disables the channel. Typical input current is less than
10μA. These pins must not be allowed to float.
LO (Pin 16): Single-Ended Local Oscillator Input. This
pin is internally connected to the primary side of the LO
input transformer and has a low DC resistance to ground.
Series DC-blocking capacitors should be used to avoid
damage to the integrated transformer when DC voltage
is present at the LO input. The LO input is internally
matched to 50Ω for all states of ENA and ENB.
I
SEL
(Pin 18): Low Current Select Pin. When this pin is
pulled low (<0.3V), both mixer channels are biased at the
normal current level for best RF performance. When greater
than 2.5V is applied, both channels operate at reduced
current, which provides reasonable performance at lower
power consumption. This pin must not be allowed to float.
