64-GS/s 6-Bit Track-and-Hold Circuit with More Than 61 GHz Bandwidth at 1.0 Vpp Input Voltage Swing in 90-nm SiGe BiCMOS Technology

Time-interleaving of energy-efficient data converter cores enables record symbol rates in electronic receivers. High-speed applications like optical data transmission or direct down-conversion in wireless mmWave receivers require ultra-high bandwidths and symbol rates, which CMOS data converters and especially their analog front ends cannot provide to date. We demonstrate a 64-GS/s track-and-hold circuit with a large-signal bandwidth of more than 61 GHz without any area-consuming peaking inductors, designed and manufactured in a 90-nm SiGe BiCMOS technology. The analog sampling front end exhibits a third harmonic distortion of -45 dBc to -32 dBc within the available frequency range of 50 GHz, which is better than the 5-bit requirement for 1.0-Vpp input signals. The ultra-high bandwidth of the circuit is twice as high as reported for CMOS data converters and in the range of broadband germanium photodiodes. This improves the bottleneck in hybrid integrated optoelectronic receiver front ends significantly. It is suited for time-interleaving of two channels with a doubled symbol rate of 128 GBaud, and the linearity allows to use it with 6-8-bit data converters.