Large bandwidth tunable analog equalizers based on an InP DHBT differential pair amplifier cell for 100-GBaud communication systems

We report the design, simulations and measurements of two tunable analog equalizers. These circuits have been realized using indium phosphide heterojunction bipolar transistors reaching f
_T
/f
_max
of 370/340 GHz. These analog equalizers provide a bandwidth of more than 100 GHz, depending on the settings. A varactor is used to tune the frequency response to equalize various types of 100-GBaud communication system channels.