Mixed-integrator biquad for continuous-time filters

Author

Chen, Yuanfeng ; Mak, Pui-In ; Zhou, Yangzhong

Author_Institution

Inst. of Microelectron., Chinese Acad. of Sci., Beijing, China

Volume

46

Issue

8

fYear

2010

Firstpage

561

Lastpage

563

Abstract

A mixed-integrator biquad (MIB) combining the advantageous features of a g_m-C integrator and a source-follower-based (SFB) integrator is proposed. Unlike the conventional pure SFB biquad suffering from significant passband gain loss, the MIB employs a linearised g_m-C integrator at the front, overcoming the gain loss, and an SFB integrator at the back, guaranteeing good linearity and low-output impedance. The complex poles are synthesised through a negative feedback technique avoiding the need of a common-mode feedback circuit. An experimental fourth-order MIB-based Butterworth lowpass filter fabricated in 0.18 ??m CMOS shows improved figure-of-merit with respect to the state-of-the-art, while occupying a small die area.

Keywords

Butterworth filters; CMOS integrated circuits; band-pass filters; circuit feedback; continuous time filters; electric impedance; low-pass filters; mixed analogue-digital integrated circuits; Butterworth lowpass filter; CMOS; SFB integrator; common-mode feedback circuit; complex poles; continuous-time filter; figure-of-merit; g_m-C integrator; low-output impedance; mixed-integrator biquad; negative feedback; passband gain loss; size 0.18 mum; source-follower-based integrator;

fLanguage

English

Journal_Title

Electronics Letters

Publisher

iet

ISSN

0013-5194

Type

jour

DOI

10.1049/el.2010.0544

Filename

5451006