A novel dynamically reconfigurable bandpass filter (BPF) employing stepped impedance resonators (SIRs) that can operate as either a single-band or a dual-band filter is demonstrated. The reconfigurable BPF uses four p-in diodes as switching elements. With the four p-in diodes in the "OFF" state, the filter behaves as a low-loss (0.85 dB) single-band BPF with a passband around 2.45 GHz. The reconfigurable SIR filter can operate as a dual-band bandpass filter with two center frequencies at 1.6 GHz and 2.45 GHz. The diodes are dynamically set to the "ON" state in the presence of a 1.6 GHz RF signal that is received by an RF triggered power management unit (PMU), integrated on the back side of the microstrip filter in a dual-layer architecture. The RF triggered PMU consists of a PIFA antenna, a highefficiency voltage doubler rectifier (47% at-13 dBm) and an active dc-to-dc power booster. The rectified output voltage is used as the enabling voltage for the dc-to-dc power booster. This, in turn, provides the required dc power for the diodes biasing. The filter switches from single-band to dual-band when a wireless input RF signal (>-13 dBm) is received by the RF triggered PMU's antenna. Index Terms-Microwave filter, reconfigurable, rectenna wireless power transfer. I. INTRODUCTION HERE has been an increasing demand for switchable and reconfigurable microwave devices, such as filters for wireless communication systems, where several different wireless devices co-exist and share the same frequency spectrum. Band pass filters (BPFs) with multi-frequency response and high stopband rejection are widely used, therefore reconfigurable BPFs can be utilized for controlling either standalone signals or combinations of information signals, with different frequency spectrum characteristics [1], [2]. In [1] a
