High speed metamaterial-inspired negative group delay circuits in CMOS for delay equalization

Two metamaterial-inspired CMOS integrated circuits for millimetre-wave frequencies of operation are investigated that utilize lumped element components and tuneable varactors in an LC ladder configuration for negative group delay (NGD) values. Measurement and simulation results of a passive, fixed transmission line (TL) structure are presented along with an equivalent circuit model. Realized NGD values are observed from 20 to 24 GHz with a minimum value of −84 ps. By the addition of an accumulation-mode varactor the proposed circuit can be made tuneable; measured NGD values from 13.3 to 26.2 GHz are observed. These high speed circuits may be useful to minimize group delay (GD) variations generated by active and passive devices and thus can act as delay equalizers when placed in cascade. Concepts are illustrated by reducing GD in lowpass (LP), highpass (HP) and bandpass (BP) filters. The proposed circuits can be useful to reduce unwanted dispersion effects in silicon-based devices and systems and high speed interconnects at millimetre-wave frequencies.