Methods and circuit for suppressing transients in an output driver and data conversion systems using the same
AssigneeCirrus Logic, Inc.
InventorsStephen Timothy Hodapp, Timothy Thomas Rueger, Bruce Eliot Duewer
Life of this patent
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Abstract
A driver circuit with power-down transient suppression includes an amplifier for driving a load coupled to an output of the amplifier, a ramp-down voltage generator having a capacitor and a resistor for generating a ramp-down voltage during power-down of the amplifier, and a differential transistor pair responsive to the ramp-down voltage for pulling-down current at the output of the amplifier during power-down of the amplifier.
Claims19
A driver circuit with power-down transient suppression comprising:
- an amplifier for driving a load coupled to an output of the amplifier;
- a ramp down voltage generator including a capacitor and a resistor for generating a ramp-down voltage during power-down of the amplifier;
- and
- a differential transistor pair responsive to the ramp-down voltage for pulling-down current at the output of the amplifier during power-down of the amplifier wherein at least one transistor of the differential pair implements an offset such that an initial current pulled-down from the output of the amplifier is approximately zero.
A method of suppressing transients at an output of an amplifier driving a load, comprising:
- generating a ramp-down voltage with a capacitor and a resistor during power-down of the amplifier;
- and
- pulling-down current at the output of the amplifier during power-down of the amplifier with a differential transistor pair responsive to the ramp-down voltage wherein at least one transistor of the differential pair implements an offset such that an initial current pulled-down from the output of the amplifier is approximately zero.
A digital to analog converter system comprising:
- a digital to analog converter array;
- an operational amplifier coupled to an output of the digital to analog converter array for driving an output load:
- a common mode reference generator for setting a common mode output voltage of the operational amplifier, the common mode reference generator including a first resistor for charging a reference capacitor during steady state operation of the operational amplifier and a second resistor for discharging the reference capacitor during power-down of the operational amplifier to generate a ramp-down signal;
- and
- a ramp-down signal generator for pulling current from an output of the operational amplifier during power-down in response to the ramp-down signal.
Dependencies are inferred from the claim text.