RF2948B RF Micro Devices, RF2948B Datasheet - Page 5

• Manufacturer Part Number: RF2948B
• Description: 2.4GHz SPREAD-SPECTRUM TRANSCEIVER
• Manufacturer: RF Micro Devices

Rev A6 040930
Pin
10
11
12
1
2
3
4
5
6
7
8
9
RX IF BIAS
Function
RX IF IN
TX IF IN
TX VGC
PA OUT
RX EN
VCC1
VCC9
VCC8
VCC6
IF LO
PD
Description
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.
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.
When this pin is a logic “high”, the device is in receive mode. When this
pin is a logic “low”, the device is in transmit mode.
Shunt resistor of 23.7±1% to ground. Biases IF AMPS.
Power supply for RX VGA amplifier, IC logic and RX references.
IF input for receiver section. Must have DC-blocking cap. The capacitor
value should be appropriate for the IF frequency. For half-duplex opera-
tion, connect RX IF IN and TX IF IN signals together after the DC block-
ing 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.
Input for the TX IF signal after SAW filter. External DC-blocking cap
required. For half-duplex operation, connect RX IF IN and TX IF IN sig-
nals 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.
Power supply for the TX 15dB gain amp and TX VGA.
Gain control setting for the transmit VGA. Positive slope.
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 100Ω shunt resistor at this input to con-
strain the mismatch.
Power supply for IF LO buffer and quadrature phase network.
Power supply for transmitter bias generator.
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 V
supplies DC and a series cap.
CC
, which
Interface Schematic
See pin 1.
See pin 6.
Image Filter
SAW
Filter
3, 4, 5
Pins
IF
TX RF
IF VCO
From
Recommended Matching
RF2948B
Network for IF LO
100 Ω
PA IN
10 kΩ
50 Ω µstrip
Bias
150 pF
C
22 nF
C2
BYP
VCC
ESD
V
CC
PA OUT
L
14 mA
Block
C
DC
11-243
IF LO
Pin 9
Logic
Pin 7
Pin 8
Power
Output
Amp
To