Compact hairpin bandpass filter with silicon-based integrated passive device technology for Ka-band application

In this paper, the design of a miniaturized Ka-band hairpin bandpass filter (BPF) with low insertion loss has been demonstrated. The proposed BPF is composed of a three-order hairpin structure together with two coupled lines leading to the chip pads. Chip-scale package is applied with flip-chip bonding, in order to minimize the interconnection parasitics. Measured with a probe setup, the BPF has a bandwidth of 6 GHz at the center frequency of 33 GHz, ranging from 30 GHz to 36 GHz. An insertion loss of 2.3 dB and a return loss better than 10 dB are achieved throughout the passband. Implemented in a high resistivity silicon integrated passive device process, the BPF features a compact core area of 2 mm
²
.