US 12,633,882 B2 · Amplifier with overvoltage protection

Abstract

In described examples, a circuit includes a reference voltage, a driving circuit with a driving input and a driving output, an output transistor, and a clamp circuit with a clamp input and a clamp output. The output transistor includes a source, a drain, and a gate; the source is coupled to receive the reference voltage. The clamp input is coupled to the driving output and to the gate. The clamp output is coupled to either the driving input or to the driving output, the gate, and the clamp input. The clamp circuit is configured to detect an operating region of the output transistor and to generate a clamping current after the output transistor enters a triode region. The clamping current is selected to prevent an absolute value of a source-gate voltage of the output transistor from equaling or exceeding a gate oxide tunneling voltage of the output transistor.

Claims20

Dependent claims

A circuit, comprising:

a reference voltage terminal adapted to receive a reference voltage;
a driving circuit including a driving input and a driving output;
an output transistor including a source, a drain, and a gate, the source coupled to the reference voltage terminal;
and
a clamp circuit including a clamp input and a clamp output, the clamp input coupled to the driving output and to the gate, the clamp output coupled to either the driving input or to the driving output, the gate, and the clamp input, the clamp circuit configured to detect an operating region of the output transistor and to generate a clamping current after the output transistor enters a triode region, the clamping current selected to prevent an absolute value of a source-gate voltage of the output transistor from being greater than or equal to a gate oxide tunneling voltage of the output transistor.

2 more elements

A circuit, comprising:

a reference voltage terminal adapted to receive a reference voltage;
a driving circuit including a driving input and a driving output;
an output transistor including a first source, a first drain, and a first gate, the source coupled to the reference voltage terminal;
and
a clamp circuit including a first clamping transistor, a second clamping transistor, a current mirror including a first side and a second side, and a resistive element including a first resistor terminal and a second resistor terminal;
wherein the first clamping transistor includes a second source, a second gate, and a second drain, the second source coupled to the reference voltage, the second gate coupled to the driving output and the first gate, and the second drain coupled to a current path of the first side, a bias response of the first clamping transistor configured to match a bias response of the output transistor;
wherein the first resistor terminal is coupled to the reference voltage;
and
wherein the second clamping transistor includes a third source, a third gate, and a third drain, the third source coupled to the reference voltage, the third gate coupled to the second resistor terminal and to a current path of the second side, and the third drain coupled either to the driving input or to the first gate and the driving output.

6 more elements

A circuit, comprising:

a reference voltage terminal adapted to receive a reference voltage;
a control input terminal adapted to receive a control voltage;
a driving circuit including a driving input and a driving output;
an output transistor including a first source, a first drain, and a first gate, the source coupled to the reference voltage terminal;
a clamp circuit including a first clamping transistor, a second clamping transistor, a current mirror including a first side and a second side, and a resistive element including a first resistor terminal and a second resistor terminal;
and
an amplifier including an amplifier input and an amplifier output and having a gain, the amplifier input coupled to receive a voltage responsive to the control voltage;
wherein the first clamping transistor includes a second source, a second gate, and a second drain, the second source coupled to the reference voltage, the second gate coupled to the driving output and the first gate, and the second drain coupled to a current path of the first side, a bias response of the first clamping transistor configured to match a bias response of the output transistor;
wherein the first resistor terminal is coupled to the reference voltage;
and
wherein the second clamping transistor includes a third source, a third gate, and a third drain, the third source coupled to the reference voltage, the third gate coupled to the second resistor terminal and to a current path of the second side, and the third drain coupled either to the driving input and the amplifier output or to the first gate and the driving output.

8 more elements

Dependencies are inferred from the claim text.

Amplifier with overvoltage protection

Life of this patent

Amplifier with overvoltage protection

Life of this patent

Abstract

Claims20