Broadband Parametric Circulator with Balanced Monolithic Integrated Distributedly Modulated Capacitors (DMC)

Distributedly modulated capacitors (DMC) is a discrete realization of time-varying transmission line (TVTL), which offers broadband nonreciprocity through time modulation of the transmission line property and compensating the circuit loss with the parametric gain [2-4]. The low-noise, broadband behavior of the DMC and its IC compatibility makes it ideal for Simultaneous Transmit and Receiving (STAR) applications. In this paper, a MMIC implementation of the DMC is presented with its performance experimentally verified. Furthermore, a circulator prototype consisting of a pair of DMC MMICs in a balanced architecture is assembled and tested. More than 25 dB TX-to-RX isolation and less than 4 dB RX loss is demonstrated in the experiment over the frequency of 0.7 to 2.5 GHz.