Digitally-controlled analogue signal processing and conversion techniques employing a logarithmic building block

This paper describes digitally-controlled analogue signal processing and conversion techniques based on a logarithmic current attenuator building block fully compatible with digital CMOS technology, and whose accuracy depends solely on the matching of transistors. Application examples given to illustrate the proposed techniques include logarithmic analogue-to-digital and digital-to-analogue conversion and automatic gain control, functions commonly used in various communications and instrumentations applications