Theory and Design of $N$ -Push BJT Clamping Harmonic Generator for Silicon Terahertz ICs

We present a $N$ -push BJT clamping harmonic generator and an optimal operation condition is derived to maximize the desired $N ^{th}$ harmonic component. Under the hard switching condition, harmonic currents are calculated from time domain waveform generated from a simplified BJT model. Output waveform and the harmonic currents match well with Harmonic Balance (HB) simulation. For verification, measurements from a 380 GHz quadrupler with the on-chip patch antenna implemented in 0.13 $\mu{\rm m}$ SiGe BiCMOS are presented. Optimal biasing point for maximum EIRP corresponds well with the calculated value.