Tektronix 371B, Service Manual

Page: 63 / 292

Theory of Operation
371B Service Manual
3-3
This circuitry supplies stimulus to the device under test. It consists of the
following circuits:
Phase lock loop (PLL) and clock circuit
Step generator circuit
Step amplifier circuit
Collector supply generator
Collector supply amplifier
High-voltage output
High-current output
The PLL and clock circuit supplies clock signals to the collector supply
generator, step generator, high current output, and acquisition circuits. These
clock signals are synchronized to the line frequency.
The step generator circuit generates a fixed-amplitude step voltage and an offset
voltage from the clock signal received from the PLL and clock circuit. The
signal is amplified as a current step signal or voltage signal by the step amplifier,
then output to the STEP GENERATOR VOLTAGE or STEP GENERATOR
CURRENT connector.
The collector supply generator generates two types of signals: a sine-square
waveform generated from the clock signal received from the PLL and clock
circuit, and a DC signal. These signals are output at an amplitude selected by the
collector supply VARIABLE control on the front panel.
The collector supply amplifier amplifies the sine-square waveform and sends it
to the high voltage output circuit. There the signal is stepped up by a transform-
er, then output to the COLLECTOR SUPPLY HIGH VOLTAGE connector.
The high-current output circuit reshapes the DC signal into a voltage pulse signal
by means of control signals from the PLL and clock circuit. Then it is amplified
and sent to the COLLECTOR SUPPLY HIGH CURRENT connector.
This group of circuitry consists of circuits that sense, acquire, and display the
effect that the collector supply and step generator circuits have on the device
under test (DUT). These circuits include:
Horizontal sense circuit
Vertical sense circuit
Sense board interface circuit
Display offset circuit
Collector Supply and Step
Generator
Data Acquisition and
Display