Theory Of Operation; Introduction; General Description; Block Diagram - HP 3300A Technical Manual

Model 3300A
4-1.

INTRODUCTION.

4-2. This section contains a description of the theory
of operation of the -hp- Model 3300A Function Generator
with the -hp- Model 3301A Auxiliary Plug-in.
4-3.

GENERAL DESCRIPTION.

4-4. The Model 3300A contains a frequency control
network, two current sources, a triangle integrator, a
voltage comparator multivibrator, a sine wave synthesizer
and output amplifiers. (Refer to Figure 4-1
4-5. The Model 3301A Auxiliary Plug-in provides
internal connections
operation.
4-6. The voltage comparator multivibrator, current
sources and triangle integrator form the basic function
generating loop. The voltage comparator multivibrator
changes state at predetermined limits on the positive and
negative slopes of the output of the triangular integrator.
This change of state shuts off the upper current source,
reverses the input to the triangle integrator. A cycle is as
follows: when the amplitude of the positive slope of the
triangle wave reaches the upper predetermined limit of
the voltage comparator multivibrator, the multivibrator
changes state. This change of state reverses the current
into the triangle integrator through control of the upper
current source which causes the output of the integrator
to decrease. The decrease continues until the amplitude
of the negative slope reaches the lower predetermined
limit. At this point, the voltage comparator multivibrator
changes state and again reverses the direction of current
at the input of the integrator and causes the output of the

THEORY OF OPERATION

which facilitate Model
Figure 4-1. Block Diagram
SECTION IV
integrator to rise. This rise continues until the voltage
comparator multivibrator again changes state thus
completing the cycle.
4-7. The
internally by the FREQUENCY Dial or externally through
the FREQUENCY CONTROL, determines the amount of
current in the current sources, which varies the frequency
as follows: an increase or decrease in input current
increases or decreases the slope of the triangle wave,
respectively.
reverses the slope. ) Frequency will increase if the + and
- slopes are increased, as less time is required for the +
or - slope of the triangle wave to reach the predetermined
limits in the voltage comparator multivibrator.
3300A
4-8. The sine wave is synthesized from the triangle
wave by a nonlinear network. This network consists of
resistors and diodes biased so different diodes conduct
during different voltage levels of the triangle wave. These
diodes, when conducting, provide additional shunt paths
within the network. Each additional shunt path changes
the slope of the triangle wave so that the wave is shaped
to a sine wave.
4-9. The output amplifiers are dc coupled and fully
floating with respect to power line ground. CHANNEL A
and CHANNEL B amplifiers are identical and use a
differential amplifier at the input. To maintain the same
peak-to-peak amplitude regardless of function selected,
the overall closed loop gain of the amplifier is varied with
function selection.
4-1
frequency control network,
(A change in direction of input current
Section IV
governed