IPD bandpass filter chip based on the filter prototype realized by new compact resonators

In this paper, a resonator based on a coupled inductor and a capacitor is proposed to obtain a pole and a zero concurrently. This resonator has a compact layout with a size of only an inductor. This paper describes the idea of constructing filter circuit completely based on this type of resonator and presents a method to realize the equivalence between networks of the resonators and classical filter prototypes. Bandpass filters based on the resonators can be realized to verify the feasibility of the method. A filter chip with a size of 2.01 × 1.21 mm 2 is realized by the integrated passive device (IPD) technology. The operation frequency with | S 11 | < −10 dB and | S 22 | < −10 dB covers 4.93–6.15 GHz, two out-of-band poles are 0.87 GHz and 0.45 GHz away from the passband edges respectively, the measured insertion loss is 2.04 dB.