0-dB insertion loss miniaturized third-order 2.54GHz CMOS active bandpass filter

This paper presents a miniaturized 2.54GHz active bandpass filter (ABPF) which is implemented with the new complementary-conducting-strip transmission line (CCS-TL). The proposed CCS-TL contains multiple synthetic transmission lines in a unit cell. Additionally, the negative resistance network, which is realized by the differential cross couple pair, is applied to compensate the ohmic loss of the proposed CCS-TL. The prototype is implemented with the standard 0.18um CMOS 1P6M process. The on-wafer measurements are conducted to demonstrate the proposed CMOS ABPF with the following characteristics. The third-order ABPF occupies the area of 0.51% ¿₀ by 0.71% ¿₀ at the center frequency, 2.54GHz with 13 % bandwidth. As the 11mA current from +1.8 V power supply is fed in the filter, at 2.54 GHz, the insertion is 0 dB with 0.843-dB in-band ripple and the return loss is 17.212 dB with three apparent reflection zeros.