Analysis of totem-pole drivers in SiGe for RF and wideband applications

Abstract

This paper presents an analysis of totem-pole (TP) stages for driver applications and summarizes the major design constraints for an optimization with respect to P1dB, OIP3, and bandwidth. It is shown, that for matched drivers, in contrast to the widely applied common collector (CC) stage, class-AB TP stages offer higher output power and much higher power-added efficiencies (PAE) at comparable bandwidth. A combiner chip in 0.25 μm SiGe Bipolar CMOS (BiCMOS) verifying this concept in hardware as output driver is demonstrated proofing the increased achievable output power, which was measured greater than +0.1 dBm. This is approximately 11 dB higher than for a conventional CC driver. Furthermore, a concept is proposed, where the TP stage can act as a broadband matched driver for differential or balun operation ranging down to DC. As verification a broadband driver design using a class-AB TP stage is presented, which has a 3 dB bandwidth of 7.9 GHz and delivers up to +4.3 dBm into a 50 Ω load, which is 17 dB higher than its CC counterpart. At this output power it consumes a DC power of 12.3 mW and yields a PAE of 16.1%.