Romanian Journal of Information Science and Technology (ROMJIST)

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ROMJIST is a publication of Romanian Academy,
Section for Information Science and Technology

Editor – in – Chief:
Academician Dan Dascalu

Secretariate (office):
Adriana Neagu
Adress for correspondence: romjist@romjist.ro

Editing of the printed version: Mihaela Marian (Publishing House of the Romanian Academy, Bucharest)

Sponsor: National Institute
for R & D in Microtechnology
(IMT Bucharest)

ROMJIST Volume 20, No. 4, 2017, pp. 301-312, Paper no. 567/2017
 

Cornel Stanescu, Cristian Dinca, David Mcdonald, David Paul
A 24 V Chopper Offset-Stabilized Operational Amplifier with Symmetrical RC Notch Filters having sub-10 µV offset and over-120dB CMRR

ABSTRACT: The paper presents a 24 V chopper offset-stabilized operational amplifier with symmetrical RC notch filters, having a 4-24 V supply range, and being realized using a 0.25 µm BCD process. The amplifier has a typical offset voltage of 1.2 µV, a minimum PSRR of 128 dB, a minimum CMRR of 120 dB, a minimum open-loop gain of 134dB, a noise PSD of 30 nV/√Hz, 1.8 MHz unity gain bandwidth, and THD + noise of 0.0004 % at 1 kHz, while consuming 500 µA. The chopping frequency is 250 kHz. The input chopping clock phases are obtained using a level shifter. Using minimum sized isolated NMOS transistors as switches, the input current was reduced down to maximum 100pA at room temperature.

KEYWORDS: Chopper offset-stabilized operational amplifier, high voltage, level shifter, offset voltage, notch filter, bandwidth, slew-rate, noise

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