Non-linear Modeling and Harmonic Balance Simulations of Track and Hold Amplifier

A novel extraction of a non-linear circuit model of dual-rank Track and Hold (THA) amplifier is presented. The non-linear model is based on the Spurious Free dynamic Range (SFDR) measurements versus input frequency of commercially available Teledyne RTH090 THA with an analog bandwidth of 28 GHz using Harmonic Balance (HB) algorithm. A Non-Linear (NL) conductance switch model of the THA corrected with Lanczos weighting factors has been first theoretically analyzed and then extracted. To our knowledge, it is the first time that such a non-linear THA circuit model has been simulated. The simulations have been performed from S-Band up to Ka-Band frequencies. The measurement results and the simulations are compared at 0.3V
_p-p
input signal and a differential clock signal of 0.8V
_p-p
with sampling rates varying between 2-4 GSps. The HB simulations of the non-linear model fits well with the measurement results.