Analysis of continuous-time digital signal processors

Continuous-time digital signal processors avoid sampling, and thus do not suffer from aliasing of the signal, or of aliasing down of out-of-band distortion components, arising from quantization, into the band of interest. The reduction of in-band distortion is derived analytically for certain symmetric inputs and is discussed for input processes with a Gaussian amplitude probability density function. It is demonstrated that processing in continuous time yields a 9 dB improvement of in-band signal-to-distortion ratio per added bit of quantizer resolution for both input classes examined, compared to a 6 dB per bit improvement in sampled systems.