Computer Generation of Digital Filter Banks

In order to reduce the design time of digital filter bank circuits, a design system has been developed. The software consists of the filter compiler which converts high level filter descriptions to hardware descriptions and the layout generator which converts the hardware descriptions to a layout file. To verify the algorithms before fabrication, a test system is employed. The development time of this system was kept to a minimum by designing the hardware to be easily micro coded and assembled. Several circuits have been fabricated and tested that were generated with this system, including a single bandpass filter chip, a 112-pole 16-channel filter bank for a speech recognition system and a 16-channel spectrum analyzer for consumer stereo applications. The speech recognition chip achieved a SNR of 80 dB with an area of 25 mm ² in a 4-micron NMOS technology.