Design Elliptic Lowpass Filter with Inductively Compensated Parallel-Coupled Lines

This paper presents a simple technique to design an ellicptic transfer fuction microstrip lowpass filter based on a ection of doubly inductive compensated parallel-coupled lines. The proposed lowpass filter has the suppression performance to suppress the signal transmission in transition and stopband better than the filter based on the conventional coupled lines. The proposed design procedures are convenient with the closed form design equation. To emonstrate the techniques performance, simulated and measured results at 0.9 GHz cut off frequency LPF with ncompensated and the compensated structures are compared. The measured results obtained from the proposed LPF exhibit 0.2 dB insertions, less than 20 dB return loss and more suppression performance than 35 dB at 1.8 GHz.