0.8/2.2-GHz Programmable Active Bandpass Filters in InP/Si BiCMOS Technology

Programmable active bandpass filters (BPFs) have been designed in a chip-scale heterogeneous integration technology, which intimately integrates InP HBTs on a deep scaled CMOS technology. Therefore, the active BPF can leverage both high performance of InP HBT and high density and programmability of CMOS. Two BPF prototypes, consisting of a programmable gain amplifier (PGA), a fifth- or third-order BPF core, and a buffer, have been designed and fabricated. The BPF center frequency can be switched from 0.8 to 2.2 GHz with 150-MHz passband and delivers > 55-dB out-of-band (OOB) rejection for the fifth-order one. Four gain steps: 0, 6, 12, and 16 dB, are enabled by the front PGA to trade off noise and linearity performances. Due to the > 300-GHz f T of InP HBTs, the BPF cores can leverage active-RC architecture for high linearity owing to the close-loop implementation. The fifth-order BPF prototype occupies a 1.5 × 1.02 mm
²
area together with pads and draws 106/121 mA from a 3.3-V power supply for 0.8/2.2-GHz bands, respectively, which demonstrates OOB output third-order intercept points (OIP3s) of 22.69/21.25 dBm for 0.8/2.2-GHz bands at the high gain mode. The measurement results suggest the fifth-order BPF core achieves 36.69/35.25-dBm OOB OIP3s. In addition, the designed third-order programmable BPF has been successfully used as a technology yield vehicle to assist the BiCMOS technology development.