Integrated differential 2 GHz 2.7V low-noise active bandpass filters on silicon

Silicon technology in CMOS and BiCMOS processes are now showing very interesting intrinsic characteristics. Two 2-GHz 2.7 V differential filter topologies are designed and analyzed in this paper. The first circuit is a filter based on an LC-Q enhanced topology, consuming less than 6.1 mA. It shows at the center frequency a 20-dB power transmission gain, a noise figure of 4.2 dB, a -35 dBm 1-dB input referred compression point and a -3 dB bandwidth of 50 MHz. The second circuit is a fourth-order bandpass filter developed and realized using four inductors electrically coupled with MOSFETs consuming 5.5 mA/pole. With a bandwidth of 43 MHz, a transmission gain of 34 dB and a noise figure of 4.4 dB at 2.05 GHz center frequency. Varactor diodes are used for frequency tuning. An amplifier is cascaded at the input for noise and impedance matching. Philips QUBIC4 Si BiCMOS technology is used (D. Szmyd et al., Proc. 2001 Bipolar/BiCMOS Circuits Tech. Meeting, pp. 60-63, 2001).