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.
Authors
Additional information
- DOI
- Digital Object Identifier link open in new tab 10.2478/bpasts-2013-0074
- Category
- Publikacja w czasopiśmie
- Type
- artykuł w czasopiśmie wyróżnionym w JCR
- Language
- angielski
- Publication year
- 2013
