Tunable Nonlinear Transmission Lines with switched varactors

Nonlinear Transmission Lines (NLTLs) have been used in many applications for waveform shaping and impedance engineering. To minimize insertion loss and jitter, adaptive impedance is desirable. Here we propose to use switched varactors on NLTL to achieve impedance-tuning. We present an analytical model to examine the impact of switch parasitics on the performance of the NLTL. We find that for a narrow range of switch series resistance, the NLTL can be made to compress the opposite edge of the input pulse. We report the first observation of this reverse-edge sharpening phenomenon in NLTLs fabricated with 0.18 mum SOI technology.