A pnp-npn Folded Cascode 240-GS/s 2-to-1 Analog Multiplexer in Complementary 130-nm SiGe BiCMOS

A new pnp − npn folded cascode return-to-zero Analog Multiplexer (AMUX) topology is proposed. It minimizes the supply voltage without compromising speed compared to npn-only topologies by taking advantage of a complementary SiGe BiCMOS process with fast pnp SiGe HBTs. Operation at a record 240 GS/s is measured by sampling sinusoidal inputs at each lane on both phases of a 120-GHz clock signal. The AMUX operation is demonstrated by multiplexing two PAM-4 or NRZ PRBS-13 input signals to obtain 192-GBaud (384-Gb/s) PAM-4 and 210-GBaud (210-Gb/s) NRZ output symbol (bit) rates, the highest reported to date for a silicon-based transmitter. The AMUX consumes 0.7 W from 1.8 V and 3.3 V supplies.