New low-voltage low-power VM All-Pass Filter using Current Follower with non-unity gain

In this paper, a new realization of a first-order voltage-mode (VM) All-Pass Filter (APF) using a grounded capacitor, three resistors, and a single Current Follower (CF) with non-unity gain is presented. The number of external resistors in the proposed VM APF can be reduced to two by considering the input intrinsic resistance of the CF as a useful active parameter. In comparison to the second-generation current conveyor-based current follower implementations employing large number of metal-oxide-semiconductor field-effect transistors (MOSFETs), here the used CF is composed of only four MOSFETs. Hence, it is favorable for low-voltage low-power circuit design. The APF was designed at pole frequency of 9.8 MHz with 112 μW power consumption using PTM 90 nm level-7 CMOS process BSIM3v3 parameters and with ±0.5 V DC voltages. SPICE simulation results are included to support the theory.