On the design of all-digital components for low-speed and high-speed modems using MOS technology

Discusses ways to realize at reasonable costs purely digital low-speed and high-speed modems. In the first case, very simple digital filter configurations with very coarsely quantized coefficients are used in the receiver, whereas the transmitter consists of a counter and a sine-table stores in a ROM. In high-speed modems, the modulator uses the elementary function synthesis method with the provision that only increments have to be stored, requiring a very small ROM capacity. The receiver filter uses a novel scheme in which the function given by the filter difference equation is generated by a sequential algorithm that requires only a ROM of small storage capacity and an adder. For any arbitrary filter with a frequency band small compared with the operating speed of modern MOS components, this approach to digital filter realization may be of general interest.