Quasi-Complementary BiCMOS For Sub-3-V Digital Circuits

Abstract

This paper describes a quasi-complementary BiCMOS (QC-BiCMOS) circuit scheme for the low-supply-volt- age deep-submicrometer regime. A QC-BiCMOS performs twice as fast as a CMOS even at a 2.5-V supply without a p-n-p bipolar transistor. Key circuits for this excellent low-voltage performance are a separation between the base of the pull-up bipolar and the base of a quasi-p-n-p, and the carefully designed base discharging circuit. Based on these circuits, a quasi-p-n-p combination of a PMOS and an n-p-n bipolar shows an equiva- lent cutoff frequency over 10 GHz. The delay expressions for the QC-BiCMOS are analyzed and compared with the conventional BiCMOS. A fabricated 0.3-pm fully loaded three- gate verifies more than twice the performance leverage over the conventional BiCMOS and the CMOS at sub-3-V supply.