POWER AMPLIFIER
This unit includes Q50 1-Q507 and attenuator. Any waveform passed through Function Switch and
entered VR502 and R501 to get divided voltage and then amplify again. VR502 is the amplification
adjustment for the instrument and has adjustment range of
20dB. Its adjustment ratio
=
VRS0~6;'01
=
lK+
l2
?-
100 (time)
=
40dB.
Q50
1
and
9502
make differential amplifier
and
its amplification ratio
12
R511
18K
is determined by the R5 1 1 and R5 10 its ratio value, amplification ratio
A=
~510
=
2~
=
9
(time),
i.e. input 2.5Vp-p signal after amplified its amplification will be larger than 20Vp-p. VR501 is internal
D.C offset adjustment;
VR503 is external DC offset adjustment. Its theory is that to input one positive or
negative DC level to Q502; base makes defection of differential output to positive or negative.
Q504, Q505 are to compensate
V
bias; Q506 and Q507 are typical pushpull power output, and its
purpose is to amplify current; its voltage gain constantly is
1,
R5 16 and R5
17
prevent class-AB
pushpull amplification from making crossover distortion.
C502 and C503 are decoupling that can reduce output, because supply source noise makes interference.
R518 and R5 19 are the output impedance of the instrument. R520, R52 1 construct attneuator, its
attenuation is -20dB effect. Output impedance is still maintained at 50Q
(OHM).
CIRCUIT OF FREQUENCY COUNTER
U601 (GFC 9701) is the main part of this unit. The Frequency Counter is
an
ASIC which developed by
our company.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
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