Voltage reference generator for quickly charging capacitive loads
AssigneeSGS-Thomson Microelectronics S.A.
InventorsTien-Dung Do, Mathieu Lisart
Life of this patent
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Abstract
A voltage reference generator includes a voltage source and a differential amplifier. The voltage source supplies a stable voltage reference to a positive input of the differential amplifier which is configured as a follower having its output looped back to its negative input. The negative feedback loop is a variable-resistance loop that is controlled by the output of the differential amplifier. The variable-resistance feedback loop transiently imposes open-loop operation when the voltage reference generator is turned on so as to provide high current to the output before imposing closed-loop operation in follower mode.
Claims36
A voltage reference generator comprising:
- a differential amplifier having positive and negative inputs and an output;
- a voltage source to supply a stable reference voltage to the positive input of the differential amplifier, the differential amplifier being configured as a follower with the output of the differential amplifier looped back to the negative input to form a negative feedback loop;
- wherein the negative feedback loop is a variable-resistance negative feedback loop controlled by the output of the differential amplifier in order to impose, transiently, an open-loop operation when the voltage source is turned on in such a way as to provide high current at the output of the differential amplifier before imposing a closed-loop operation in follower mode.
An integrated circuit comprising:
- a voltage reference generator that includes a differential amplifier and a voltage source, the differential amplifier having positive and negative inputs and an output and the voltage source supplying a stable reference voltage to the positive input of the differential amplifier, the differential amplifier being configured as a follower with the output of the differential amplifier looped back to the negative input to form a negative feedback loop;
- wherein the negative feedback loop is a variable-resistance negative feedback loop controlled by the output of the differential amplifier in order to impose, transiently, an open-loop operation when the voltage source is turned on in such a way as to provide high current at the output of the differential amplifier before imposing a closed-loop operation in follower mode;
- and
- wherein the voltage reference generator has a control input to receive a control signal that enables the voltage reference generator to provide a generated output voltage on demand in response to an assertion of the control signal.
A method of generating an output voltage, comprising the steps of:
- generating a stable reference voltage;
- and
- responsive to an assertion of a first signal:
- supplying a first amount of output current to a capacitive line to rapidly charge a voltage level of the capacitive line to a voltage level of the stable reference voltage in response to the step of generating;
- reducing the first amount of output current supplied to the capacitive line as the voltage level of the capacitive line increases;
- and
- outputting a second amount of current to maintain the voltage level of the capacitive line at the voltage level of the stable reference voltage.
A voltage reference generator, comprising:
- a voltage source having an output to supply a steady reference voltage;
- a differential amplifier having positive and negative inputs and an output, the positive input being coupled to the output of the voltage source;
- and
- a variable-resistance negative feedback loop, coupled between the output of the differential amplifier and the negative input of the differential amplifier, to provide approximately open loop gain in a first state and approximately unity gain in a second state based upon a voltage level of the output of the differential amplifier.
A voltage reference generator, comprising:
- a voltage source having an output to supply a steady reference voltage;
- a differential amplifier having positive and negative inputs and an output, the positive input being coupled to the output of the voltage source;
- and
- negative feedback means, coupled between the output of the differential amplifier and the negative input of the differential amplifier, for varying a gain of the differential amplifier from an approximately open loop gain to an approximately unity gain based on a voltage level of the output of the differential amplifier.
Dependencies are inferred from the claim text.