Compact Filtering Switch With Wide-Stopband Response

• Main Authors: Jin-Xu Xu, Xiu Yin Zhang, Yan-Mei Xue
• Format: Article
• Language: English
• Published: IEEE 2017-01-01
• Series: IEEE Access
• Subjects: RF switch; bandpass responses; wide-stopband; lumped-element loaded resonator; compact size; high isolation
• Online Access: https://ieeexplore.ieee.org/document/8089729/

A compact filtering switch with wide-stopband responses is presented in this paper. The resonator is designed using microstrip transmission lines and lumped capacitors. It is utilized to shift up the second harmonic frequency for wide-stopband performance and miniaturize the circuit size. In the ON-state, the circuit is the same as the bandpass filter without signals passing through the p-i-n diode, which avoids additional loss introduced by p-i-n diode. Two transmission zeros are generated near the passband to enhance the skirt selectivity. In the off-state, the signals from port 1 to port 2 passing through different transmission path are cancelled out, resulting in high isolation. For demonstration, a filtering switch operating at 780 MHz is implemented with the compact size of 0.072λ_g×0.066λ_g. More than 20-dB suppression levels are measured from 0.89 to 5.3 GHz (6.8 f0), featuring wide-stopband responses.