8-56
RF2444
Rev A3 010717
8
Pin
Function
Description
Interface Schematic
1
GAIN SEL
LNA gain control. When GAIN SEL is > VCC- 300mV, LNA gain is at 10
dB. When GAIN SEL is <300mV, the LNA gain is -6dB.
See pin 16.
2LNA IN
This pin is NOT internally DC blocked. An external blocking capacitor
must be provided if the pin is connected to a device with DC present. If
a blocking capacitor is required, a value of 2pF is recommended.
See pin 16.
3PD
The power enable pin. When PD is > VCC- 300mV, the part is biased
on. When PD is <300mV, then the part is turned off and typically draws
less than 1
µA.
4
VCC1
Supply voltage for bias circuits and logic control. A 10pF external
bypass capacitor is required and an additional 0.01
µF is required if no
other low frequency bypass capacitors are nearby. The trace length
between the pin and the bypass capacitors should be minimized. The
ground side of the bypass capacitors should connect immediately to
ground plane.
5
VCC2
Supply voltage for LO_Buffer. A 10pF bypass capacitor is required and
an additional 0.01
µF is required if there is no other low frequency
bypass capacitor in the area. The trace length between the pin and the
bypass capacitors should be minimized. The ground side of the bypass
capacitors should connect immediately to ground plane.
See pin 8.
6MIXOUT-
The inverting open collector output of the mixer. This pin needs to be
externally biased and DC isolated from other parts of the circuit. This
output can drive a Balun, with MIXOUT+, to convert to unbalanced to
drive a SAW filter. The Balun can be either broadband (transformer) or
narrowband (discrete LC matching). Alternatively, MIXOUT+ may be
used alone to drive a SAW single-ended, with an RF choke (high Z at
IF)fromVCC to MIXOUT-.
7MIXOUT+
The non-inverting open collector output of the mixer. This pin needs to
be externally biased and DC isolated from other parts of the circuit.
This output can drive a Balun, with MIXOUT+, to convert to unbalanced
to drive a SAW filter. The Balun can be either broadband (transformer)
or narrowband (discrete LC matching). Alternatively, MIXOUT+ may be
used alone to drive a SAW single-ended, with an RF choke (high Z at
IF)fromVCC to MIXOUT+.
See pin 6.
8LO IN
LO input pin. This input needs a DC blocking cap. External matching is
recommended to 50
Ω.
9RX EN
This control pin allows the mixer output pins to be put into a high
impedance state. This allows the transmit signal path to share the
same IF filter as the receiver.
10
VCC3
Supply voltage for mixer preamp.
See pin 12.
11
GND3
Ground pin for mixer preamp. This lead inductance should be kept
small.
See pin 12.
12
MIX IN
Mixer RF Input port. This pin is NOT internally DC blocked. An external
blocking capacitor must be provided if the pin is connected to a device
with DC present. A value of >22pF is recommended. To minimize the
noise figure it is recommended to have a bandpass filter before this
input. This will prevent the noise at the image frequency from being
convertedtothe IF.
MIX OUT+
MIX OUT-
LO IN
VCC2
VCC3
GND3
MIX IN
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