Implementation of a 5-Ghz LTCC bandpass filter using vertically-interdigitated capacitors and via engineering

Abstract

A low-temperature cofired ceramic (LTCC) LC resonator bandpass filter for 5-GHz wireless LAN applications is implemented. The miniaturization of the filter is achieved by utilizing vertically-interdigitated capacitors as resonator capacitors, and the required small inductance (similar to 0.1 nH) is realized by via holes. The inductances of via-holes connecting the capacitor plates also considerably affect the filter characteristics, and they are considered in circuit design stage of the filter. The fabricated bandpass filter has five layers with the size of 2.4 x 4.18 x 0.56 mm(3). The measured center frequency, bandwidth, and insertion loss are 5.32 GHz, 340 MHz, and 2.87 dB, respectively. (c) 2007 Wiley Periodicals, Inc.