High-Performance Three-Stage Single-Miller CMOS OTA With No Upper Limit of

• Published in: IEEE transactions on circuits and systems. II, Express briefs Vol. 65; no. 11; pp. 1529 - 1533
• Main Authors: Grasso, Alfio Dario, Marano, D., Palumbo, G., Pennisi, S.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-11-2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Art exhibits; Capacitors; Circuit stability; CMOS; Digital audio players; Gain; large capacitive loads; Miller compensation; multistage amplifiers; Operational amplifiers; Operational transconductance amplifiers; Slew rate; Small signal analysis; Stability analysis; State of the art; Transconductance; Transistors
• DOI: 10.1109/TCSII.2017.2756923
• EISSN: 1558-3791
• ISSN: 1549-7747

This brief presents a low-power, area-efficient three-stage CMOS operational transconductance amplifier (OTA) suitable for very large capacitive loads, <inline-formula> <tex-math notation="LaTeX">{C} _{L} </tex-math></inline-formula>. A single Miller capacitor and an inverting current buffer embedded in the input stage are exploited to implement the frequency compensation network. An additional feed-forward path and a slew rate enhancer are also utilized to improve the large-signal transient response. Detailed small-signal analysis reveals that the proposed OTA does not exhibit an upper limit of drivable <inline-formula> <tex-math notation="LaTeX">{C} _{L} </tex-math></inline-formula>. The OTA is fabricated in a standard 0.35-<inline-formula> <tex-math notation="LaTeX">{\mu }\text{m} </tex-math></inline-formula> technology and occupies 0.0027 mm 2 of die area. Under 1.4-V supply and 6.36-<inline-formula> <tex-math notation="LaTeX">{\mu }\text{A} </tex-math></inline-formula> quiescent current consumption, it provides a dc gain greater than 110 dB and is stable for any <inline-formula> <tex-math notation="LaTeX">{C} _{L} </tex-math></inline-formula> larger than 5 nF. Comparison with the state of the art shows remarkable improvement of both small- and large-signal performance.