23. Analog-To-Digital Converter Adjustments

23. Analog-To-Digital Converter Adjustments

Reference

Description

A3A8 Analog-to-Digital Converter

The Analog-to-Digital Ramp Converter is adjusted at zero and full-scale by injecting a 0 V dc input and + 10 V dc input and adjusting the OFFS and GAIN controls until the ramp output at A3A8TPll toggles high to low. This sets the horizontal end points for the CRT trace display; when the sweep ramp input is at 0 V dc (the left graticule edge), trace position 1 is set, and when the sweep ramp input is at + 10 V de (the right graticule edge), trace position 1000 is set.

This procedure requires a + 10 V dc source which is stable and noise-free. A simple supply circuit which can be built with common components is illustrated in Figure 3-93. If these components are unavailable, the alternate procedure provided below (using only the digital voltmeter) can then be used.

. -

1’7

HP 54501A

OlGlTlZlNG

OSCILLOSCOPE

DIGITAL VOLTKTER

Figure 3-85. Analog-To-Digital Converter Adjustments Setup

Equipment Oscilloscope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HP 54501 Digital Voltmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HP 3456A Low-Noise DC Supply (Optional) . . . . . . . . . . . . . . . . . . . . . See Figure 3-93

Adjustments 3-139