# Microwave Negative Group Delay Circuit: Filter Synthesis Approach

• Park, Junsik (Division of Electronics and Information Engineering, IT Convergence Research Center, Chonbuk National University) ;
• Chaudhary, Girdhari (Division of Electronics and Information Engineering, IT Convergence Research Center, Chonbuk National University) ;
• Jeong, Junhyung (Division of Electronics and Information Engineering, IT Convergence Research Center, Chonbuk National University) ;
• Jeong, Yongchae (Division of Electronics and Information Engineering, IT Convergence Research Center, Chonbuk National University)
• Accepted : 2015.11.24
• Published : 2016.01.31
• 89 8

#### Abstract

This paper presents the design of a negative group delay circuit (NGDC) using the filter synthesis approach. The proposed design method is based on a frequency transformation from a low-pass filter (LPF) to a bandstop filter (BSF). The predefined negative group delay (NGD) can be obtained by inserting resistors into resonators. To implement a circuit with a distributed transmission line, a circuit conversion technique is employed. Both theoretical and experimental results are provided for validating of the proposed approach. For NGD bandwidth and magnitude flatness enhancements, two second-order NGDCs with slightly different center frequencies are cascaded. In the experiment, group delay of $5.9{\pm}0.5ns$ and insertion loss of $39.95{\pm}0.5dB$ are obtained in the frequency range of 1.935-2.001 GHz.

#### Keywords

Bandstop Filter;Frequency Transformation;Filter Approach;Low Pass Filter Prototype;Negative Group Delay

#### Acknowledgement

Supported by : National Research Foundation of Korea (NRF)

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