Wideband third-order single-transistor all-pass filter

In this letter, a third-order wideband voltage-mode all-pass filter (APF) is proposed for application as a true time delay (TTD) cell. The advantages of designing a single-stage higher order filter over cascading several lower order stages are illustrated. The proposed APF circuit is based on a single metal-oxide-semiconductor (MOS) transistor and is canonical because it requires one resistor, one inductor, and two capacitors. To the best of the authors' knowledge, this is the first single-transistor third-order APF circuit to be reported in the literature. The operation of the proposed APF is validated through post-layout simulations in a 65-nm CMOS technology. The simulation results demonstrate a group delay of 59.4 ps across a 13.2-GHz bandwidth with a maximum delay-bandwidth product of 0.783, while consuming only 3.54mW from a 1-V supply voltage. Moreover, the designed circuit achieves an input-referred IP3 of 19.95 dBm and occupies an area of 161.5μm × 204.8μm. © 2020 John Wiley & Sons, Ltd.