3.3-V BiCMOS circuit techniques for a 120-MHz RISC microprocessor

This paper describes 3.3-V BiCMOS circuit techniques for a 120-MHz RISC microprocessor. The processor is implemented in a 0.5-μm BiCMOS technology with 4-metal-layer structure. The chip includes a 240 MFLOPS fully pipelined 64-b floating point datapath, a 240-MIPS integer datapath, and 24 KB cache, and contains 2.8 million transistors. The processor executes up to four operations at 120 MHz and dissipates 17 W. Novel BiCMOS circuits, such as a 0.6-ns single-ended common base sense amplifier, a 0.46-ns 22-b comparator, and a 0.7-ns path logic adder are applied to the processor. The processor with the proposed BiCMOS circuits has a 11%-47% shorter delay time advantage over a CMOS microprocessor