Gate capacitor stress reduction in CMOS/BICMOS circuit

A read channel for a hard disk drive, comprising:

• a first circuit having one of an input and an output that at least one of receives and generates, respectively, a voltage that varies and that has a maximum voltage value;
• a gate capacitor including a thin gate oxide layer semiconductor device having a gate, a source and a drain, wherein the gate communicates with the at least one of the input and the output of the first circuit, and wherein the semiconductor device has a voltage rating that is less than the maximum voltage value;
• and
• a first bias supply that biases the source and the drain of the semiconductor device with a nonzero bias voltage that is substantially fixed and has a value that is greater than a difference between the maximum voltage value and the voltage rating.

An electrical circuit for amplification of a signal, comprising:

• first circuit means having one of an input and an output for at least one of receiving and generating a voltage that varies and that has a maximum voltage value;
• gate capacitance means for providing a capacitance and including a thin gate oxide layer semiconductor device with a gate, a source and a drain, wherein the gate communicates with the at least one of the input and the output of the first circuit, and wherein the semiconductor device has a voltage rating that is less than the maximum voltage value;
• and
• means for biasing the source and the drain of the semiconductor device with a nonzero bias voltage that is substantially fixed and has a value that is greater than a difference between the maximum voltage value and the voltage rating.

An apparatus for using a gate capacitor, which has a voltage rating, without breakdown in a circuit that has an operating voltage that exceeds the voltage rating of the gate capacitor, comprising:

• a gate capacitor including a thin gate oxide layer semiconductor device with a gate, a source and a drain;
• a first circuit that has one of an input and an output that at least one of receives and generates, respectively, a voltage that varies and that has a maximum voltage value that exceeds the voltage rating of the gate capacitor;
• a first bias supply that biases a source and a drain of the semiconductor device with a nonzero bias voltage that is substantially fixed and has a voltage value that is greater than a difference between the maximum voltage value and the voltage rating;
• and
• means for coupling the at least one of the input and the output of the first circuit to the gate of the semiconductor device.

An apparatus for using a gate capacitor, which has a voltage rating, without breakdown in a circuit that has an operating voltage that exceeds the voltage rating of the gate capacitor, comprising:

• gate capacitance means for providing a capacitance and including a thin gate oxide layer semiconductor device with a gate, a source and a drain;
• first circuit means that has one of an input and an output for at least one of receiving and generating, respectively, a voltage that varies and that has a maximum voltage value that exceeds the voltage rating of the gate capacitor;
• means for biasing the source and the drain of the semiconductor device with a nonzero bias voltage that is substantially fixed and has a voltage value that is greater than a difference between the maximum voltage value and the voltage rating;
• and
• means for applying a reference voltage to a substrate to which the semiconductor device is connected.

A method for preventing breakdown of a gate capacitor, which has a voltage rating, when used in a circuit that has an operating voltage that exceeds the voltage rating of the gate capacitor, comprising:

• providing a gate capacitor including a thin gate oxide layer semiconductor device with a gate, a source and a drain;
• providing a first circuit that has one of an input and an output that at least one of receives and generates, respectively, a voltage that varies and that has a maximum voltage value that exceeds the voltage rating of the gate capacitor;
• coupling the at least one of the input and the output of the first circuit to a gate of the semiconductor device;
• and
• biasing the source and the drain of the semiconductor device with a nonzero voltage that is substantially fixed and has a voltage value that is greater than a difference between the maximum voltage value and the voltage rating.

A method for preventing breakdown of a gate capacitor, which has a voltage rating, when used in a circuit that has an operating voltage that exceeds the voltage rating of the gate capacitor, comprising:

• providing a gate capacitor including a thin gate oxide layer semiconductor device with a gate, a source and a drain;
• providing a first circuit that has one of an input and an output that at least one of receives and generates, respectively, a voltage that varies and that has a maximum voltage value that exceeds the voltage rating of the gate capacitor;
• coupling the at least one of the input and the output of the first circuit to a gate of the semiconductor device;
• biasing the source and the drain of the semiconductor device with a nonzero voltage that is substantially fixed and has a voltage value that is greater than a difference between the maximum voltage value and the voltage rating;
• and
• applying a reference voltage to a substrate of the semiconductor device.