High-density 16/8/4-bit configurable multiplier

A configurable serial-parallel multiplier based on Braun´s and Baugh-Wooley´s algorithms is presented. The multiplier can be configured to perform either signed or unsigned multiplications and to achieve variable precision. In this device one factor A(m) is fed serially with an arbitrary wordlength m while the other B(n) is stored in parallel with a configurable number of bits n=4, 8 or 16 bits. Switch elements are used to change the hardware connection between adjacent 4-bit multiplier basic blocks. This reconfiguration concept provides a higher precision multiplier by grouping adjacent cells or a higher throughput at low levels of precisions. A prototype of this multiplier has been fabricated using a full custom 1.0 μm CMOS technology. The active area contains 3450 transistors and occupies 0.47 mm² corresponding to a very high gate density of 1532 gates/mm²