Amplifier with a low offset voltage

Abstract

Abstract 1. An amplifier with a low offset voltage, including a plurality of switches, a control circuit for controlling same and two operational amplifiers whose outputs are respectively connected to the amplifier output by way of a first terminal of first and second switches respectively, wherein the two operational amplifiers (1, 2) are alternately and in push-pull relationship with each other in an "auto-zero" phase (A1 and A2 respectively) or in an amplification phase (C1 and C2 respectively) characterised in that the operational amplifiers (1, 2) each have first and second non-inverting and first and second inverting inputs and that each of the two operational amplifiers (1 and 2), following its "autozero" phase (A1 and A2 respectively) and before beginning its amplification phase (C1 and C2 ) is additionally non-overlappingly in a preparation phase (B1 and B2 respectively), that the first non-inverting inputs are respectively connected by way of a second terminal (8b and 9b) of the first and second switches respectively to the non-inverting amplifier input (3), by way of a first terminal (10a and 11a) fo third and fourth switches respectively to the output of the other operational amplifier (2 or 1 respectively) and by way of a first terminal (12a and 13a) of fifth and sixth switches respectively to earth, and the first inverting inputs are respectively connected by way of a third terminal (8c and 9c) of the first and second switches respectively to the inverting amplifier input (4), by way of a second terminal (10b and 11b) of the third and fourth switches respectively to the output of the associated operational amplifier (1 and 2) and by way of a second terminal (12b and 13b) of the fifth and sixth switches respectively to earth, that the second inverting input is respectively connected by way of a third terminal (12c and 13c) of the fifth and sixth switches respectively to the output of the associated operational amplifier (1 and 2) and it is connected to earth by way of a capacitor (6 and 7 respectively) associated with the respective operational amplifier (1 and 2) while the second non-inverting input is connected directly to earth, wherein closed in timed succession in the sequence specified hereinafter are either only the second and fifth switches (9, 12), the second and third switches (9, 10), the first and sixth switches (8, 13) or the first and fourth switches (8, 11).

Inventors

• 👤 Jacob De Vries

Bibliographic Details