Title :
Design of a Gm-C low pass filter with low cutoff frequency
Author :
Liu, Haidong ; Peng, Xiaohong ; Wu, Wuchen
Author_Institution :
VLSI & Syst. Lab., Beijing Univ. of Technol., Beijing, China
Abstract :
The design of a low-cutoff-frequency Gm-C low-pass filter is presented, the key part in the filter, the operational transconductance amplifier utilize a folded-cascode structure. As the circuit is desired to operate at low frequency, it is necessary to design a small linear trans-conductance amplifier employing a cross-coupled input stage. To compensate the gain loss, the auxiliary amplifiers are added. The differential pairs are offsetted in the sub-threshold zone, and an appropriate adjustment of the operating point can effectively curve the transconductance as a function of temperature. The filter is fabricated in a 0.18 ¿m CMOS process, operating with a 1.8 V supply and using a bias current of 4 ¿A. The results show that the cutoff frequency of low-pass filter can be 10 kHz, and the maximum deviation arising from variations of temperature is 0.0016 dB/°C. The total power consumption is 225 ¿W with a total capacitance load of 60 pF.
Keywords :
CMOS integrated circuits; integrated circuit design; low-pass filters; operational amplifiers; CMOS process; Gm-C low pass filter; auxiliary amplifier; capacitance 60 pF; current 4 muA; differential pairs; folded-cascode structure; frequency 10 kHz; low cutoff frequency; operational transconductance amplifier; power 225 muW; size 0.18 mum; small linear transconductance amplifier; subthreshold zone; voltage 1.8 V; Band pass filters; Capacitors; Circuits; Cutoff frequency; Laboratories; Low pass filters; Operational amplifiers; Temperature; Transconductance; Very large scale integration;
Conference_Titel :
Microelectronics & Electronics, 2009. PrimeAsia 2009. Asia Pacific Conference on Postgraduate Research in
Conference_Location :
Shanghai
Print_ISBN :
978-1-4244-4668-1
Electronic_ISBN :
978-1-4244-4669-8
DOI :
10.1109/PRIMEASIA.2009.5397432
