This chapter presents some latest developments in microwave transversal and recursive filter-based negative group delay (NGD) circuits as well as their applications in realizing non-Foster elements. By using transversal and recursive-filter approaches, the desired amount of NGD can be synthesized with enhanced bandwidth. The fully distributed topology of the proposed NGD circuits makes it feasible to scale up to higher frequency ranges such as millimeter waves. In addition, it is demonstrated that the transversal-filter-based NGD circuit can realize non-Foster elements with unconditional stability, enabling a new approach to realizing stable non-Foster elements.

Chapter Contents:

• Abstract
• Keywords
• 4.1 Introduction
• 4.2 Transversal filter-based NGD circuits
• 4.2.1 Passive realization
• 4.2.2 Active realization
• 4.2.3 Voltage-insensitive stepped-impedance DA-based NGD circuit
• 4.3 Recursive filter-based NGD circuits
• 4.4 Non-Foster element using active transversal-filter-based NGD circuit
• 4.5 Conclusion
• References

Inspec keywords: microwave filters; active networks; recursive filters; delay circuits; transversal filters

Other keywords: recursive filter; distributed topology; microwave transversal filter; negative group delay circuits; NGD circuits; nonFoster elements

Subjects: Pulse circuits; Active filters and other active networks; Digital filters