RF2642
Pin
1
2
Function
GND
RF OUT
Description
Ground connection. For best performance, keep traces physically short
and connect immediately to ground plane. This pin is internally con-
nected to the die flag.
Output match of the second stage of the power amplifier driver. This
amplifier output pin is open collector. It is matched to 50Ω externally
using a simple LC match. Refer to the application schematic.
Interface Schematic
Gain
Select
RF OUT
3
RF GND2
The ground connection for the second stage of the power amplifier
driver. The inductance between this pin and the ground plane deter-
mines the gain of the second stage. Increased inductance results in
reduced gain.
On the evaluation board, the emitter ground inductance is set by the
length of the PCB trace connected between this pin and the ground. By
sliding a 0Ω ground jumper along this line, the inductance, and hence
the gain, may be varied.
The evaluation board is shipped with the 0Ω jumper very close to the
part, resulting in minimum inductance, and therefore maximum second
stage gain. This translates to higher output IP3 and maximum ACPR1.
This setting results in performance 6dB better than the ACPR1 mini-
mum specification of 50dBc in the CDMA IS-95 specification for a
P
OUT
=+5dBm.
The ground connection for the first stage of the power amplifier driver.
The inductance between this pin and the ground plane determines the
gain of the first stage. Increased inductance results in reduced gain.
On the evaluation board, the emitter ground inductance is set by the
length of the PCB trace connected between this pin and the ground. By
sliding a 0Ω ground jumper along this line, the inductance, and hence
the gain, may be varied.
The evaluation board is shipped with the 0Ω jumper far away from the
part, resulting in maximum inductance, and therefore minimum first
stage gain.
More gain may be obtained by shifting the 0Ω jumper toward the part.
A maximum total gain of 40dB may be achieved if the first stage is set
to minimum emitter inductor trace length.
Power supply pin for the first stage power amplifier. External compo-
nents provide tuning for the interstage match.
RF input to the power amplifier. This input is DC-coupled, so an exter-
nal blocking capacitor is needed if the pin is connected to a DC path.
See pin 3.
PCB
Trace
4
RF GND1
5
6
VPA1
RF IN
Bias
VPA1
RF IN
7
PD
8
MIX OUT
Power Down control When this pin is low, the amplifier section of the IC
is shut off. When this pin is high, the amplifier section of the IC is turned
on. The upconverter portion of the IC remains on regardless of the
state of PD.
Output for the upconverting mixer. This input is DC-coupled, so an
external blocking capacitor is needed if the pin is connected to a DC
path. The output impedance is 50Ω.
MIX OUT
9
GND
Same as pin 1.
Rev A8 060925
6-51
RFMD [ RF MICRO DEVICES ]
