DocumentCode :
2552146
Title :
Sub-circuit analysis for power supply rejection ratio in regulated cascode operational transconductance amplifiers and filters
Author :
Bhattacharyya, A.B. ; Dey, Saudas
Author_Institution :
Inst. of Technol. & Manage., Haryana, India
fYear :
1999
fDate :
7-10 Jan 1999
Firstpage :
164
Lastpage :
168
Abstract :
Operational Transconductance Amplifiers (OTA) form an integral part of OTA-C filters. The authors have experimented with OTA-C filters for frequency shaping purposes in micropower all-CMOS hearing aids as against conventionally used switched capacitor filters, as switched capacitor filters present problem due to switching noise and require a double polysilicon technology in a low voltage process. The power supply rejection ratio (PSRR) of such filters becomes important in hearing aids, as the negative supply voltage for the OTA is derived from the low voltage battery by the use of a dc to dc converter through capacitor switching where a ripple voltage on supply rail is inherent due to charging and discharging mechanism in the converter circuit. A regulated cascode (RGC) differential stage is used for OTA to increase the linearity of the differential input stage and ensure an acceptable level of CMRR. An important finding that has emerged in the present investigation from the viewpoint of application of OTA-C filters in hearing aids is that PSRR of high pass filter is much higher compared to that in low pass configuration. The results have been validated both by SPICE simulation and measurement of OTA-C filter chips fabricated for hearing aid application
Keywords :
CMOS analogue integrated circuits; SPICE; active filters; circuit simulation; hearing aids; high-pass filters; low-pass filters; low-power electronics; operational amplifiers; SPICE simulation; charging mechanism; dc to dc converter; differential input stage; discharging mechanism; double polysilicon technology; frequency shaping purposes; high pass filter; low pass configuration; low voltage process; micropower all-CMOS hearing aids; operational transconductance amplifier filters; power supply rejection ratio; regulated cascode operational transconductance amplifiers; ripple voltage; sub-circuit analysis; Batteries; Capacitors; Filters; Frequency; Hearing aids; Low voltage; Noise shaping; Operational amplifiers; Power supplies; Transconductance;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
VLSI Design, 1999. Proceedings. Twelfth International Conference On
Conference_Location :
Goa
ISSN :
1063-9667
Print_ISBN :
0-7695-0013-7
Type :
conf
DOI :
10.1109/ICVD.1999.745143
Filename :
745143
Link To Document :
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