Space efficient CMOS nonlinear transmission lines

Nonlinear transmission lines (NLTLs) are used in diverse applications such as edge-sharpening, pulse generation, and frequency conversion, however, length of a useful NLTL can require significant MMIC or RFIC real estate. We present an analytical model for the complex propagation constant of lossy, distributed NLTLs and fabricate several NLTLs in 0.25 mum CMOS for verification. Space-saving layout techniques such as serpentine folding and floating-grid substrate shielding are fabricated and we examine their impact on the edge-sharpening performance of the NLTLs.