A SiGe-HBT 2:1 analog multiplexer with more than 67 GHz bandwidth

This paper presents a 2:1 Analog Multiplexer (AMUX) in a SiGe-HBT technology. The AMUX is used for time interleaving operation of two digital-to-analog converters (DACs) and therefore extends both the sampling rate and the bandwidth compared to a single DAC. The linear AMUX signal path allows for generation of broadband signals with higher order modulation schemes which is essential for raising data rates in optical communication networks. The AMUX provides a differential peak-to-peak output voltage of up to 1 V with linear gain. A signal path 3-dB bandwidth exceeding 67 GHz has been measured. The clock path exhibits a 3-dB bandwidth of 60 GHz. S-parameter measurements are presented. Measured PAM4 eye diagrams at 56 GS/s from the time interleaving operation of two DACs are reported.