Balanced Dispersive Delay Circuit With Common-Mode Suppression and Filtering Characteristics

A novel balanced dispersive delay circuit (DDC) with common-mode (CM) suppression and bandpass filtering characteristics is proposed for signal integrity, analog signal processing, and group delay equalization. The utilization of parallel coupled lines not only achieves a bandpass filtering response for differential-mode signals but also suppresses the transmission of common-mode noise as well as port matching characteristics. The in-band large linear group delay shape is generated by configuring phase-asymmetric transmission paths at both ends of the stub-loaded microstrip lines. The introduction of lumped resistors can be used to adjust the linearity of the in-band group delay. To further validate the workability of the design, a microstrip prototype of the balanced filtering DDC with a simple circuit structure is fabricated and measured. Compared to the reported DDCs, the proposed one not only has in-band linear group delay and bandpass filtering responses but also extends the DDC to the balanced topology to realize an excellent CM suppression characteristic for the first time.