2-6
RF2938
Rev A8 010418
11
Pin
Function
Description
Interface Schematic
17
NC
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
18
PA IN
Input to the power amplifier stage. This is a 50
Ω input. Requires DC
blocking/tuning cap.
See pin 14.
19
NC
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
20
VCC5
Supply for the RF LO buffer, RF upconverter and amplifier.
21
RF LO
Single ended LO input for the transmit upconverter. External matching
to 50
Ω and a DC block are required.
See pin 20.
22
RF OUT
Upconverted Transmit signal. This 50
Ω output is intended to drive an
RF filter to suppress the undesired sideband, harmonics, and other out-
of-band mixer products.
See pin 20.
23
IF1 OUT-
The inverting open collector output of the quadrature modulator. This
pin needs to be externally biased and DC isolated from other parts of
the circuit. This output can drive a Balun with IF1 OUT+, to convert to
unbalanced to drive a SAW filter. The Balun can be either broadband
(transformer) or narrowband (discrete LC matching). Alternatively, just
IF1 OUT+ can be used to drive a SAW single-ended with an RF choke
(high Z at IF) from VCC to IF1 OUT-.
24
NC
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
25
IF1 OUT+
The non-inverting open collector output of the quadrature modulator.
This pin needs to be externally biased and DC isolated from other parts
of the circuit. This output can drive a Balun with IF1 OUT-, to convert to
unbalanced to drive a SAW filter. The Balun can be either broadband
(transformer) or narrowband (discrete LC matching). Alternatively, just
IF1 OUT+ can be used to drive a SAW single-ended with an RF choke
(high Z at IF) from VCC to IF1 OUT+.
See pin 23.
26
TXI BP
This is the in-phase modulator bypass pin. A 10nF capacitor to ground
is recommended.
27
TXI DATA
I input to the baseband 5 pole Bessel LPF for the transmit modulator.
28
TXQ BP
This is the quadrature modulator bypass pin. A 10nF capacitor to
ground is recommended.
29
TXQ DATA
Q input to the baseband 5 pole Bessel LPF for the transmit modulator.
30
VCC4
Power supply for quadrature modulator.
31
I OUT
Baseband analog signal output for in-phase channel.
500mVP-P linear output.
32
RXI DATA
Logic-level data output for the in-phase channel. This is a digital output
signal obtained from the output of a Schmitt trigger.
0.3V to VCC3 - 0.3V swing minimum.
33
Q OUT
Baseband analog signal output for quadrature channel.
500mVP-P linear output.
34
RXQ DATA
Logic-level data output for the quadrature channel. This is a digital out-
put signal obtained from the output of a Schmitt trigger.
0.3V to VCC3 - 0.3V swing minimum.
35
NC
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
C
BLOCK
22 pF
To TX RF
Image Filter
12 mA
From
TX VGA
V
CC
C
BYP
22 nF
VCC5
Pin 20
V
CC
C
BYP
22 nF
RF OUT
Pin 22
VB
RF LO
Pin 21
From
RF VCO
IF1 OUT+
IF1 OUT-
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