Bandwidth Tunable Low-Pass Filter Based on the Magnetic Coupling Effect

Tunable low-pass filters are vital devices of the reconfigurable RF microsystems. However, the narrow tuning ranges and large sizes of the existing filters cannot adapt miniaturization and multifunctional of the RF microsystem. This paper proposes a tunable low-pass filter, it consisting of a tunable inductor based on magnetic coupling effect and interdigital capacitor. The filter exhibits a continuously tunable bandwidth of 6.79 – 11.49 GHz with a modulation voltage range of 0 – 6 V and phase range of −152.3° to 32.6°. It has a compact area of 0.118 mm × 0.127 mm.