CMOS-based high-order LP and BP filters using biquad functions

Prommee, Pipat; Saising, Ekkapong

doi:10.1049/iet-cds.2017.0493

CMOS-based high-order LP and BP filters using biquad functions

Author(s)

Prommee, Pipat

Saising, Ekkapong

Date Issued

July 1, 2018

Type

Article

DOI

10.1049/iet-cds.2017.0493

Abstract

This study proposes the complementary metal-oxide-semiconductor (CMOS)-based current-mode high-order active low-pass (LP) and band-pass (BP) filters using biquad functions. The passive RLC Chebyshev ladder filters were used as the prototype, and the mesh- and nodal-analysis methods to derive the biquad functions. The CMOS-based transistor-level biquad circuits were subsequently realised from the biquad functions. The high-order active LP and BP ladder filters were then synthesised from an amalgamation of the biquad circuits. Simulations were carried out to verify the performance and functionality of the LP and BP ladder filters. The results revealed that the proposed ladder filters were operable in the highfrequency range and electronically tunable, given a low-voltage supply of 1 V for the entire circuit. The proposed filters could also achieve the LP frequency response of 300 kHz-30 MHz and BP centre frequency of 200 kHz-20 MHz by means of the bias current (IB) manipulation from 1 to 100 μA. Moreover, the multi-tone simulations were undertaken to assess the filtering performance of the proposed filters and the results are agreeable with the design specifications.

Citation

Iet Circuits Devices and Systems, 12(4), 326-334, 2018