SOME PROBLEMS REGARDING THE CONSTRUCTION OF ANALOG-TO-DIGITAL CONVERTERS APPLICABLE FOR LOW-LEVEL INPUT SIGNALS,
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO
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Usually for conversion of low voltages, on the order to 10-100 mv, to digital code, these voltages are first amplified by a factor of about 1000. Another method is suggested for construction of a converter which does not require pre-amplification of the signal. In this method the converter uses a high sensitivity comparison circuit sensitivity on the order of 5-10 microvolts, and a compensating voltage received from a code-to-voltage converter is fed to a divider and then to the comparison circuit. The divider achieves equality of the input and compensating voltages. A block diagram of the comparison circuit is presented and briefly described. It is a highly sensitive dc amplifier constructed on the modulation-demodulation scheme. Schematic diagrams of the transistorized keys used in the modulator and code-voltage converter are presented. It is noted that in order to provide the required accuracy of measurements, a portion of the converter must be kept under temperature control, and strobing must be used in the comparison circuit.
- Electrical and Electronic Equipment