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Chapter 5 Theory of Operation
Block Diagram
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5
Block Diagram
A block diagram is shown on the next page. The function generator’s
circuits may be divided into three main categories: power supplies, analog
circuits, and digital circuits. Each portion of the block diagram is
described in the following sections.
The line input voltage is filtered, and then applied to the main power
supply. The main power supply provides all power to the instrument.
Secondary power supplies are contained on the main circuit board.
The secondary supplies control the fan, create the –2.1 V and +3.3 V
voltages, and provide the isolated +5 V supply.
The analog circuitry begins at the Waveform DAC and continues to the
main output. Sine, ramp, noise, and arbitrary waveforms pass directly
from the Waveform DAC to the main output circuitry. Square waves and
pulses are formed in the digital waveform and variable rate edge and
level translation circuits.
The digital circuitry contains all the waveform generation circuitry and
waveform memory. The main CPU and communications CPU (outguard)
are also included.
Conventions Used on Schematics and in this Discussion
Major signal and control lines are marked with a name in uppercase.
If the name is followed by an * (for example, TRIG_SYNC*), the line
is inverted logic. If the name is followed by a lowercase e, (for example,
TRIGe), the line is the ECL-level version of a TLL or CMOS signal.
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