Tunable Delay Line Using Distributed Inductive/Capacitive Miller Effect

The Miller effect of capacitance amplification is extended to coupled transmission lines to design a new type of tunable delay line. Simultaneous variable amplification of inductance and capacitance provides a wide tuning range with constant input characteristic impedance and constant insertion loss. As a proof-of-concept, an integrated four-stage tunable delay line with a high speed phase modulation capability is implemented. The measurement shows 180° tuning range at 30 GHz with the average insertion loss of -11.6 dB and the DC power consumption of 22 mW in a 45-nm SOI CMOS technology.