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. Record 240-GS/s operation is measured by sampling sinusoidal inputs on both phases of a 120-GHz clock. The AMUX also multiplexes two PAM-4 or NRZ PRBS-13 inputs to generate 192-GBaud (384-Gb/s) PAM-4 and 210-GBaud NRZ outputs, the highest symbol rates reported to date for a silicon-based transmitter. The AMUX consumes 0.7 W from 1.8 and 3.3V supplies.