Design and simulation of fourth order low-pass Gm-C filter with novel auto-tuning circuit in 90 nm CMOS

• Published in: Analog integrated circuits and signal processing Vol. 107; no. 2; pp. 451 - 461
• Main Authors: Abdolmaleki, Mohammad, Dousti, Massoud, Tavakoli, Mohammad Bagher
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.05.2021; Springer Nature B.V
• Subjects: Circuits; Circuits and Systems; CMOS; Electrical Engineering; Engineering; Group delay; Intermodulation; Low pass filters; Manufacturing industry; Monte Carlo simulation; Operational amplifiers; Positive feedback; Power consumption; Signal,Image and Speech Processing; Simulation; Transconductance; Tuning; Equiripple linear-phase; Automatic tuning circuit; CMFB; Gm-C filter; OTA; CMOS inverters
• ISSN: 0925-1030; 1573-1979
• DOI: 10.1007/s10470-020-01785-9

A tunable high-frequency operational transconductance amplifier (OTA) is presented along with its application in the implementation of a Gm-C filter. The OTA is tuned by varying the negative resistance produced by a positive feedback at the output. Post-layout simulation results (using TSMC 90 nm CMOS technology and a 1-V supply voltage) show that the differential DC gain, common-mode gain and OTA unity gain frequency are 34 dB, −26 dB and 10 GHz, respectively. Moreover, for precise control of filter performance, an auto-tuning circuit is presented to adjust the filter cutoff frequency at low power consumption (i.e., 0.6 mW, about 16.3% of the total circuit power consumption). The filter has a cutoff frequency of 1 GHz with a group delay variation less than 6% up to 1.3 f c . The size of filter is 0.040 × 0.023mm 2 and the third order intermodulation (IM3) value at cutoff frequency is −37 dB. The Monte Carlo simulation results are presented for predicting the manufacturing process errors.