Overload recovery circuit and method

An operational amplifier comprising:

• (a) an input stage receiving an input signal and having first and second output terminals;
• (b) an output stage including a pull-up transistor having a source coupled to a first supply voltage, a gate coupled to the first output terminal, and a drain coupled to an output conductor conducting an output signal, a pull-down transistor having a source coupled to a second supply voltage, a gate coupled to the second output terminal, and a drain coupled to the output conductor, and an AB control circuit coupled between the gates of the pull-up transistor and a pull-down transistor;
• and
• (c) a first overload recovery circuit coupled between the output conductor and the gate of the pull-up transistor for limiting the voltage on the gate of the pull-up transistor in response to the output voltage when the output voltage is within a first predetermined range of the first supply voltage.

A method of operating differential input circuit including:

• (a) applying an input signal to an input stage;
• (b) providing an output stage including a pull-up transistor having a source coupled to a first supply voltage, a gate coupled to a first output terminal of the input stage, and a drain coupled to an output conductor conducting an output voltage, a pull-down transistor having a source coupled to a second supply voltage, a gate coupled to a second output terminal of the input stage, and a drain coupled to the output conductor, and an AB control circuit coupled between the gates of the pull-up transistor and a pull-down transistor;
• and
• (c) reducing the amount of time required for the differential input circuit to recover from an overload condition by limiting the voltage on the gate of the pull-up transistor in response to the output voltage when the output voltage is within a first predetermined range of the first supply voltage.

A method of operating a comparator including:

• (a) applying an input signal to an input stage;
• (b) providing an output stage including a pull-up transistor having a source coupled to a first supply voltage, a gate coupled to a first output terminal of the input stage, and a drain coupled to an output conductor conducting an output voltage, a pull-down transistor having a source coupled to a second supply voltage, a gate coupled to a second output terminal of the input stage, and a drain coupled to the output conductor, and an AB control circuit coupled between the gates of the pull-up transistor and a pull-down transistor;
• and
• (c) reducing the amount of time required for the comparator to recover from an overload condition by limiting the voltage on the gate of the pull-up transistor in response to the output voltage when the output voltage is within a first predetermined range of the first supply voltage.

A method of operating an operational amplifier including:

• (a) applying an input signal to an input stage;
• (b) providing an output stage including a pull-up transistor having a source coupled to a first supply voltage, a gate coupled to a first output terminal of the input stage, and a drain coupled to an output conductor conducting an output voltage, a pull-down transistor having a source coupled to a second supply voltage, a gate coupled to a second output terminal of the input stage, and a drain coupled to the output conductor, and an AB control circuit coupled between the gates of the pull-up transistor and a pull-down transistor;
• and
• (c) reducing the amount of time required for the operational amplifier to recover from an overload condition by limiting the voltage on the gate of the pull-up transistor in response to the output voltage when the output voltage is within a first predetermined range of the first supply voltage.