5.5 A forward-body-bias tuned 450MHz Gm-C 3rd-order low-pass filter in 28nm UTBB FD-SOI with >1dBVp IIP3 over a 0.7-to-1V supply

Due to the absence of internal nodes, inverter-based Gm-C filters [1,2] allow achieving bandwidths beyond what is possible with opamp-RC techniques. The class-AB behavior of the inverter, together with the high transconductance for a given quiescent current, results in a high dynamic range for a given power consumption when optimally biased [3]. The major disadvantage of traditional inverter-based Gm-C filters is that they are tuned with the supply voltage, V_DD, and hence require a finely controllable supply. Voltage regulators used to accomplish this require a voltage headroom (including margin for tuning) and degrade total power efficiency by tens of percent. In this paper, we show that by exploiting body biasing in an ultra-thin buried oxide (BOX) and body, fully-depleted SOI (UTBB FD-SOI) CMOS technology, we overcome the requirement for a tunable V_DD in inverter-based Gm-C filters, while achieving high linearity over a wide supply voltage range.