Dynamically Reconfigurable SIR Filter Using Rectenna and Active Booster

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 positive-intrinsic-negative (p-i-n) diodes as switching elements. With the four p-i-n 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 BPF with two center frequencies at 1.6 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 planar inverted-F antenna, a high-efficiency 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 antenna.