R_10032 Datasheet, PDF (4/10 Pages) NXP Semiconductors – CA-330-11 LDMOS bias module

NXP Semiconductors
R_10032
CA-330-11; LDMOS bias module
The temperature sensing device (Q_temp), is attached to the baseplate near the RF device
through a hole in the PCB. Its collector current is proportional to temperature, which
results in a collector voltage slope of approximately 10 mV/C. Part of this
temperature-dependent voltage is summed with the adjustable bias voltage from
potentiometer R5 to generate the temperature-compensated final bias voltage.
3.2 Gate voltage adjustment
A variable voltage derived from the 8 V supply is summed with the temperature monitor
voltage to generate a temperature-compensated gate voltage. R7 and R9 are selected to
set the desired gate voltage trim range, and R10 is selected to provide the desired amount
of temperature compensation. Figure 1 shows component values for V_GS = 2.2 0.7 V, as
given in Figure 2.
+8 V
R7
432 Ω
R13
1.1 kΩ
R4
432 Ω
3
R5 2
200 Ω
1
R8
2 kΩ
R10
10 kΩ
U2
LM7321MF
35
1
C2
42
100 nF
C1
1 μF
VGATE
R9
75 Ω
C7
100 nF
R12
5.11 kΩ
1
R11
909 Ω
3
Qtemp
BC847
2
Fig 1. Gate voltage adjustment circuit
C6
1 μF
aaa-004138
R_10032
Report
All information provided in this document is subject to legal disclaimers.
Rev. 1.0 — 24 July 2012
© NXP B.V. 2012. All rights reserved.
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