A Low-Pass Filter Type of Delta Modulation

A new method is presented for the analysis and design of a lowpass filter type of delta modulation. This system has a nonideal integrator acting as a low-pass filter in the signal band and is suited for dc transmission. Analyses are made of overload performances and signal-to-noise ratio (SNR) for sinusoidal inputs and of periodic noises for dc inputs. Point transformations, defined in the phase plane, permit us to describe algebraically the dc response of the modulator and to analyze its dc characteristics. In the results section, it is shown that asymmetric quantization contributes to improving SNR at low signal levels. A simple design method, specified with equivalent bandwidth, desired SNR, and dynamic range, is proposed and verified with experimental results obtained for a design example.