Fully‐differential flipped‐source‐follower low‐pass analogue filter in CMOS 28 nm bulk

This study presents a novel low‐pass continuous‐time filter based on the voltage flipped‐source‐follower (SF). The filter efficiently operates in CMOS 28 nm and improves the SF filters state‐of‐the‐art thanks to a dedicated circuit that operates in fully‐differential fashion (instead of the pseudo‐differential typically used in state‐of‐the‐art SF filters) with a dedicated Common‐Mode‐Feedback circuit. Thus this work extends the application of the SF filtering stages to the nm‐range technologies where threshold voltage ( V TH ) is only two times lower than the supply voltage ( V DD ) for what regards standard‐process MOS transistors. In order to validate the design concept, the proposed filter has been designed in CMOS 28 nm technology. Extensive simulation results of a 131 MHz −3 dB frequency proof‐of‐concept second‐order filter are proposed. The device consumes 510 µW power from a single 1 V supply‐voltage. In‐band integrated noise is 160 µV RMS and IIP3 is 19 dBm for 20 and 21 MHz input tones frequencies. Simulation results lead to 166 J −1 figure‐of‐merit, outperforming the analogue filter state‐of‐the‐art.