Arithmetic and Control Components for an Asynchronous System

Jianwei Liu

Abstract

This thesis describes arithmetic components (an adder and a multiplier) and control components which have been designed and implemented for AMULET3i, a commercial asynchronous embedded system chip incorporating the third generation asynchronous ARM processor (AMULET3).

A novel carry arbitration scheme is proposed (and has been patented) for parallel adder circuits. This new scheme provides an efficient encoding in which the carry is generated by arbitrating several input carry requests, exploiting the associativity of the carry computation. Post-layout simulation, in a 0.35 micron triple metal CMOS technology, shows that the adder for AMULET3i takes 1.8 ns to complete the computation of a 32-bit addition.

The multiplier design uses the modified Booth's algorithm integrated with a new encoding technique for adjusting the product result of an unsigned number multiplication. An adjustment value is made on the least significant 32-bit positions. Post-layout simulation, in a 0.35 micron triple metal CMOS technology, shows that the multiplier for AMULET3i takes 11.2 ns (2.8 ns x 4 cycles) to complete the computation of a 32-bit long multiplication in the worst case.

Organizing these arithmetic components efficiently into a four-phase asynchronous pipeline is investigated and a set of speed-independent latch control circuits is then proposed. Additionally, a set of control modules for four-phase micropipelines is presented. These two sets of control components can be used to construct complex and powerful asynchronous systems.

The thesis is available in pdf form by ftp (11.0MB)