A 5th order 0.8/2.4 GHz programmable active band pass filter for power DAC applications

A programmable active band pass filter (BPF) has 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. The BPF prototype consists of a programmable gain amplifier (PGA), a 5th order BPF core, and a buffer. The BPF center frequency is programmable from 0.8 GHz to 2.4 GHz with 150 MHz pass band and delivers >55 dB out-of-band rejection. 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 fT of InP HBTs, the BPF core can leverage active-RC architecture for high linearity owing to the close-loop implementation. The prototype occupies 1.5×1.02 mm² area together with pads and draws 106/121 mA from a 3.3 V power supply for 0.8/2.4 GHz bands respectively. In addition, the prototype demonstrates out-of-band OIP3s of 23.52/23.51 dBm for 0.8/2.4 GHz bands at the high gain mode.