A Pipelined 330-MHz Multiplier

An 8×8-bit multiplier test circuit developed in a 1-μm NMOS technology is described. To achieve a high throughput rate, extensive pipelining is used in a semi-systolic fashion. It is shown that this saves area and allows for shorter cycle times compared to a pure systolic array. Problems with widely distributed lines (broadcasting) are avoided by a novel carry-save-adder cell. The data inputs and outputs are ECL compatible. The circuit contains 5480 MOSFET's in an active area of 0.6 mm2. Effective channel lengths of 0.9 and 1.1 µm are utilized for the enhancement and depletion transistors with a gate oxide thickness of 12.5 nm. The power dissipation is 1.5 W at a supply voltage of 3 V. The test chip operates up to a clock frequency of 330 MHz at room temperature and up to 600 MHz with liquid nitrogen cooling. This demonstrates the applicability of large-scale integrated MOS circuits in a frequency range of several hundred megahertz.