Chopper-stabilized operational transconductance amplifier

DETAILED DESCRIPTION The FIG.
1 chopper-stabilized operational transconductance amplifier is constructed in COMOS technology on p-type silicon substrate electrically connected to a supply rail 11 shown as being at ground reference potential.
The substrate electrodes of n-channel field effect transistors, unless shown connected otherwise, connect to supply rail 11.
A supply rail 12 is connected to receive a relatively positive supply voltage V.
sub.
STANDARD, to which the substrate electrodes of p-channel field effect transistors connect.
A chopping control signal that switches between ground reference potential or zero voltage, and the positive supply voltage V.
sub.
STANDARD is supplied in two complementary phases S and S via respective terminals and control lines extending therefrom through the integrated circuit.
To make the circuit diagram simpler to comprehend, these control lines are omitted from FIG.
1 and further terminals for S and S are provided in FIG.
1.
A single-ended input voltage V.
sub.
IN is applied at an input terminal 13.
Catcher diodes D.
sub.
1 and D.
sub.
2 contained input terminal 13 potential to be no more than a few tenths volt more negative than rail 11 potential or more positive than rail 12 potential.
V.
sub.
IN and ground reference potential are selectively supplied to separate ones of the gate electrodes of p-channel field-effect transistors Q1 and Q2 by an input chopper switch SW1 compressing n-channel enhancement-mode field effect transistors Q3, Q4, Q5, Q6 operated as selective transmission gates.
When the S phase of the chopper control signal is high (at V.
sub.
STANDARD) and the S phase is low (at ground), Q3 and Q4 are non-conductive, but Q5 is conductive to apply ground reference potential to Q1 gate electrode and Q6 is conductive to apply V.
sub.
IN to Q2 gate electrode.
When S phase of the chopper control signal is low and S phase is high, Q5 and Q6 are non-conductive, but Q4 is conductive to apply ground reference potential to Q2 gate electrode and Q3 is conductive to apply V