A method for scanning, down conversion, and digitization of a bandpass filter - signal with the aid of a digital prediction encoder

摘要

A simple down converting A/D converter utilizing predictive coding principles. By placing the sampler inside the predictive loop, the predictive loop filter can be implemented using DSP techniques, thus eliminating the complexities introduced by use of discrete-time analog circuitry. Then, by re-mapping the output of the predictive loop filter into the analog domain using a D/A converter, the predictive filter output signal is subtracted from the input analog signal to generate the prediction error signal. Therefore, through directly sampling the prediction error signal and converting the output of the predictive loop filter into analog representation using a low-cost multiple bit D/A, the use of discrete-time analog circuitry is eliminated and the complexity of the converter design is greatly reduced. Various features of the invention are disclosed.