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PS Transverse Feedback Pick-up Amplifier |
The variable gain amplifiers are based on the Analogue Devices
AD603,
a voltage-controlled variable gain amplifier. The resistor network at the
gain control input scales the ±3V control voltage down to ±500mV. Despite
the relatively low input referred noise level, the dynamic range is
limited to about 68dB. This is due to the modest output voltage compliance
of only 1.4Vp.
The line drivers are Texas Instruments
THS3061
OpAmps. The
feedback components set the non-inverting gain to 12dB, and the series
termination drops 6dB, for a nett gain of 6dB. Powered from ±12V supplies,
these chips can drive up to 4V into a series terminated 50Ω load without
undue distortion.
