Sine Generator Circuitry - Keithley 2015 Service Manual

4-16 Troubleshooting

Sine generator circuitry

Refer to Figure 4-6 for the following discussion on the sine generator circuitry.
Figure 4-6
Sine generator circuitry block diagram
Sine Generator
OSC
U301
Distortion Digital Circuitry
Sine generator
Y302 is a fixed frequency clock that forms the input to U301, the adjustable frequency sine
wave generator. The sine wave generator' s frequency is set by the microprocessor through the
FPGA, U334, and the opto-isolators U304, U320, and U321.
Attenuator
U303, U334, U335, and U302 form the adjustable attenuator that adjusts the sine wave output
amplitude. The output amplitude is set by the microprocessor through the FPGA, U334, and the
opto-isolators U304, U320, and U321.
Inv-Sine/pulse
Attenuator
U303, U334
U335
FPGA EEPROM
(see Figure 4-4)
-1
Comparator
Filter
+1
U307
U305
U306
U307
U308
Inv Sine/
Pulse
Out
K301
50/600 Ohm
Source
Output