A High-Speed Wave Digital Filter using Carry-Save Arithmetic

To test the performance of recursive digital filters for high sampling rate applications, such as pulse former filters or filters for intermediate frequencies of TV sets and radios, a bit-parallel third order lowpass filter has been designed and fabricated in a 2 ¿m CMOS technology. This filter has a bireciprocal transfer function and is fully functional at a sampling frequency of 35 MHz. In order to obtain such high frequencies with a recursive filter, a carry-save arithmetic has been used rather than a conventional carry-propagate arithmetic. This gives rise to several realization problems which will be described in this contribution. The prototype chip contains about 9000 transistors and occupies an area of 14.7 mm².