System and method for clamping a differential amplifier
AssigneeTexas Instruments Incorporated
InventorLeland Scott Swanson
Life of this patent
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Abstract
System and method for limiting an output signal of a differential amplifier. A preferred embodiment comprises a limit sense amplifier configured to detect when the output exceeds a permitted limit, a common mode bias current unit configured to increase a signal gain of a common mode amplifier in the differential operational amplifier when the limit sense amplifier detects that the output exceeded the permitted limit, and an output stage bias current unit configured to fix the output at a level substantially equal to the specified limit when the limit sense amplifier detects that the output exceeded the permitted limit. The clamping is achieved by changing the operation of circuitry within the differential amplifier and results in a smoother clamping that helps to maintain stable operation.
Claims21
A method for clamping an output signal of an amplifier, the method comprising:
- detecting that clamping is required;
- reducing capabilities of a differential mode circuit in the amplifier;
- and
- enhancing capabilities of a common mode circuit in the amplifier.
A differential amplifier comprising:
- a limit sense amplifier coupled to an output of a differential operational amplifier, the limit sense amplifier configured to detect when the output of the differential operational amplifier exceeds a permitted limit;
- a common mode bias current unit coupled to the differential operational amplifier and the limit sense amplifier, the common mode bias current unit configured to increase a signal gain of a common mode amplifier in the differential operational amplifier when the limit sense amplifier detects that the output of the differential operational amplifier exceeded the permitted limit;
- and
- an output stage bias current unit coupled to the differential operational amplifier and the limit sense amplifier, the output stage bias current unit configured to fix the output of the differential operational amplifier at a level substantially equal to the permitted limit when the limit sense amplifier detects that the output of the differential operational amplifier exceeded the permitted limit.
A differential amplifier comprising:
- a means for detecting when an output of a means for differential operational amplifying exceeds a permitted limit;
- a means for increasing a signal gain of a means for common mode amplifying in the means for differential operational amplifying when the means for detecting determines that the output exceeded the permitted limit;
- and
- a means for fixing the output at the permitted limit when the means for detecting determines that the output exceeded the permitted limit.
Dependencies are inferred from the claim text.