Analog-digital conversion system

摘要

An analog-digital conversion system is used with a microprocessor having an algorithm by which digital signal processing is carried out by the microprocessor. The A/D conversion system converts analog signals to offset binary form for processing by the microprocessor during repetitive cycles of operation. The conversion system includes a sample-and-hold (S/H) circuit for periodically sampling the value of the analog input and an A/D converter for converting sampled input into the digital format. Timing circuitry of the system generates a plurality of control signals during each such cycle of operation. Such timing circuitry controls the S/H circuit, the A/D converter and the microprocessor, as well as a D/A converter which reconverts the processed data into analog format. Logic circuitry selectively shortens the duration of at least one interval associated with the control signals to reduce overall processing duration. Such reduction is carried out by shortening a successive timing state, and also by employing clock circuitry which switches between two different clock rates. Real-time digital processing of voice signals by the microprocessor is made possible.