2-5
RF2938
Rev A8 010418
11
Pin
Function
Description
Interface Schematic
1NC
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
2NC
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
3PD
This pin is used to power up or down the transmit and receive base-
band sections. A logic high powers up the quad demod mixers, TX and
RX GmC LPF’s, baseband VGA amps, data amps, and IF LO buffer
amp/ phase splitter. A logic low powers down the entire IC for sleep
mode. Also, see State Decode Table.
4RX EN
Enable pin for the receiver 15dB gain IF amp and the RX VGA amp.
Powers up all receiver functions when PD is high, turns off the receiver
IF circuits when low. Also, see State Decode Table.
See pin 3.
5TX EN
This pin is used to enable the transmit upconverter, buffer amps, 15db
IF amp, quad mod mixers, TX LO buffer, TX VGA, and PA driver. TX EN
is active low, when TX EN <1V, the transmit circuit is active if PD is
high. A logic high (TX EN >2V) disables the transmit IF/RF circuitry and
quad mod. Also, see State Decode Table.
See pin 3.
6VCC1
Power supply for RX VGA amplifier, IC logic and RX references.
7RX IF IN
IF input for receiver section. Must have DC blocking cap. The capacitor
value should be appropriate for the IF frequency. External matching to
50
Ω recommended. For half duplex operation, connect RX IF IN and
TX IF IN signals together after the DC blocking caps, then run a trans-
mission line from the output of the IF SAW. AC coupling capacitor must
be less than 150pF to prevent delay in switching RX to TX/TX to RX.
See pin 8.
8TX IF IN
Input for the TX IF signal after SAW filter. External DC blocking cap
required. External matching to 50
Ω recommended. For half duplex
operation, connect RX IF IN and TX IF IN signals together after the DC
blocking caps, then run a transmission line from the output of the IF
SAW. AC coupling capacitor must be less than 150pF to prevent delay
in switching RX to TX/TX to RX.
9VCC9
Power supply for the TX 15dB gain amp and TX VGA.
10
TX VGC
Gain control setting for the transmit VGA. Positive slope.
11
IF LO
IF LO input. Must have DC blocking cap. The capacitor value should be
appropriate for the IF frequency. LO frequency= 2xIF. Quad mod/
demod phase accuracy requires low harmonic content from IF LO, so it
is recommended to use an n= 3 LPF between the IF VCO and IF LO.
This is a high impedance input and the recommended matching
approach is to simply add a 100
Ω shunt resistor at this input to con-
strain the mismatch. This pin requires a 6.5
µA DC bias current. This
can be accomplished with a 270k
Ω resistor to V
CC for 3.3 V operation.
12
VCC8
Power supply for IF LO buffer and quadrature phase network.
13
NC
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
14
RF OUT
This is the output transistor of the power amp stage. It is an open col-
lector output. The output match is formed by an inductor to VCC,which
supplies DC and a series cap.
15
RF OUT
This is the output transistor of the power amp stage. It is an open col-
lector output. The output match is formed by an inductor to VCC,which
supplies DC and a series cap.
See pin 14.
16
VCC6
Power supply for the PA driver amp. This inductance to ground via
decoupling, along with an internal series capacitor, forms the interstage
match.
See pin 14.
10k
Ω
ESD
VCC
To Logic
Pins
3, 4, 5
DC Blo ck
50
Ωµstrip
IF
SAW
Filter
Pin 7
Pin 8
IF V C O
C2
15 0 p F
IF L O
Pin 1 1
R e com m e n ded M a tc hing
N e tw ork for IF LO
10 0
Ω
270 k
Ω
V
CC
From
TX RF
Image Filter
Bias
VCC6
Pin 16
V
CC
C
BYP
22 nF
V
CC
C
BYP
22 nF
PA OUT
Pin 14
PA OUT
Pin 15
PA IN
Pin 18
Power
Amp
Output
34 mA
14 mA
Bias
New Zealand ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
