Implementation of digital-serial LDI/LDD allpass filters

Sammanfattning: In this thesis, digit-serial implementation of recursive digital filters is considered. The theories presented can be applied to any recursive digital filter, and in this thesis we study the lossless discrete integrator (LDI) allpass filter. A brief introduction regarding suppression of limit cycles at finite wordlength conditions is given, and an extended stability region, where the second-order LDI allpass filter is free from quantization limit cycles, is presented.The realization of digit-serial processing elements, i.e., digit-serial adders and multipliers, is studied. A new digit-serial hybrid adder (DSHA) is presented. The adder can be pipelined to the bit level with a short arithmetic critical path, which makes it well suited when implementing high-throughput recursive digital filters.Two digit-serial multipliers which can be pipelined to the bit level are considered. It is concluded that a digit-serial/parallelmultiplier based on shift-accumulation(DSAAM) is a good candidate when implementing recursive digital systems, mainly due to low latency. Furthermore, our study shows that low latency will lead to higher throughput and lower power consumption.Scheduling of recursive digit-serial algorithms is studied. It is concluded that implementation issues such as latency and arithmetic critical path are usually required before scheduling considerations can be made. Cyclic scheduling using digit-serial arithmetics is also considered. It is shown that digit-serial cyclic scheduling is very attractive for high-throughput implementations.