Active MMIC Transversal Filter-Based Negative Group Delay/Non-Foster Circuit in 0.1-μm GaAs pHEMT Technology

A new kind of negative group delay (NGD)/non-Foster circuit using monolithic microwave integrated circuit (MMIC) technology is presented. The proposed design is based on an active transversal filter topology using a distributed amplifier (DA) with a cascode configuration at each stage, realized using WIN’s 0.1-um GaAs pseudomorphic high electron mobility transistor (pHEMT) process. Furthermore, a forward-biased Schottky barrier diode (SBD) is utilized as a phase shifter to adjust the absolute phase of S21. By properly applying the gate bias voltage and the phase shifter bias voltage, the proposed circuit can synthesize a negative capacitance of -0.3 pF with a bandwidth of 500 MHz at around 5 GHz with unconditional stability. The fabricated MMIC NGD/non-Foster circuit has a footprint of 3.05×3.15mm2 with a power consumption of 125 mW. Measurement and simulation results show great agreement with each other.