Technique to improve CMRR at high frequencies in CMOS OTA-C filters

Bulletin of the Polish Academy of Sciences. Technical Sciences

G. BlakiewiczCorresponding authorDepartment of Microelectronic Systems, Gdansk University of Technology, 11/12 Narutowicza St., 80-952 Gdansk, PolandEmailOther articles by this author:De Gruyter OnlineGoogle Scholar¹ 

[1] Department of Microelectronic Systems, Gdansk University of Technology, 11/12 Narutowicza St., 80-952 Gdansk, Poland

关键词: Keywords : common-mode rejection ratio;    CMRR;    CMOS;    OTA;    differential pair;    OTA-C filters;    component mismatch;   

DOI  :  10.2478/bpasts-2013-0074

学科分类：工程和技术（综合）

来源: Polska Akademia Nauk * Centrum Upowszechniania Nauki / Polish Academy of Sciences, Center for the Advancement of Science

【 摘 要 】

In this paper a technique to improve the common-mode rejection ratio (CMRR) at high frequencies in the OTA-C filters is proposed. The technique is applicable to most OTA-C filters using CMOS operational transconductance amplifiers (OTA) based on differential pairs. The presented analysis shows that a significant broadening of CMRR bandwidth can be achieved by using a differential pair with the bodies of transistors connected to AC ground, instead of using a pair with the bodies connected to the sources. The key advantages of the technique are: no increase in power consumption (except for an optional tuning circuit), a small increase of a chip area, a slight modification of the original filter. The simulation results for exemplary OTAs and a low-pass filter, designed in a 0.35 μm CMOS process, show the possibility of broadening the CMRR bandwidth several times.

【 授权许可】

Unknown