A Quasi-Elliptic Bandpass Filter-Integrated Single-Pole Double-Throw Switch

This paper proposes a quasi-elliptic bandpass filter- integrated single- pole double-throw ( SPDT) switch. The series-parallel configuration of p- i-n diodes embedded into the impedance matching circuit is proposed to combine two quasi-elliptic response bandpass filters to constitute the proposed SPDT switch. To validate our design approach, a proposed quasi-elliptic bandpass filterintegrated SPDT switch is designed and fabricated with a central frequency of 1.25 GHz and a 3 dB fractional bandwidth of 16%. Low insertion loss in the on state and good isolation in the off state are achieved. The switch size including bias circuits but excluding feeding lines is 0.447 lambda g x 0.134 lambda g.