Abstract: Apparatus and methods for amplifier input protection are provided. In certain implementations, an amplifier input protection circuit includes a first JFET electrically connected between a first input and a first output, and a second JFET electrically connected between a second input and a second output. Additionally, a first clamp is electrically connected to the first output, and a second clamp is electrically connected to the second output. A first current mirror mirrors a current through the first clamp, and provides the mirrored current to a third JFET electrically connected between the first JFET's source and gate. Additionally, a second current mirror that mirrors a current through the second clamp, and provides the mirrored current to a fourth JFET that is electrically connected between a source and gate of the second JFET. Configuring the protection circuit in this manner can provide the benefits of both low noise and low fault current.

Abstract: Apparatus and methods for amplifier input protection are provided. In certain implementations, an amplifier input protection circuit includes a first JFET electrically connected between a first input and a first output, and a second JFET electrically connected between a second input and a second output. Additionally, a first clamp is electrically connected to the first output, and a second clamp is electrically connected to the second output. A first current mirror mirrors a current through the first clamp, and provides the mirrored current to a third JFET electrically connected between the first JFET's source and gate. Additionally, a second current mirror that mirrors a current through the second clamp, and provides the mirrored current to a fourth JFET that is electrically connected between a source and gate of the second JFET. Configuring the protection circuit in this manner can provide the benefits of both low noise and low fault current.

Abstract: Low power low noise input bias current compensation for an amplifier input stage is provided by recycling the tail current of the differential pair transistors. A local amplifier regulates the tail current and buffers the base current of the tail current transistor, which is mirrored back to the input transistors to provide input bias current compensation.

Abstract: Apparatus and methods for reducing load-induced non-linearity in amplifiers are provided. In certain implementations, an amplifier includes a current mirror, a buffer circuit, and an output stage. The buffer circuit can have a relatively high current gain and a voltage gain about equal to 1. The buffer circuit can amplify a mirrored current generated by the current mirror and provide the amplified mirrored current to the output stage, thereby helping to balance or equalize currents in the current mirror and avoiding the impact of load-induced offset error.

Abstract: Low power low noise input bias current compensation for an amplifier input stage is provided by recycling the tail current of the differential pair transistors. A local amplifier regulates the tail current and buffers the base current of the tail current transistor, which is mirrored back to the input transistors to provide input bias current compensation.

Abstract: Apparatus and methods are disclosed related to trimming an input offset current of an amplifier. One such apparatus can include auxiliary bipolar transistors connected in parallel with bases of respective bipolar transistors of an input stage of an amplifier. The auxiliary bipolar transistors can be biased such that the base currents of the auxiliary bipolar transistors compensate for a mismatch in base currents of the bipolar transistors of the input stage of an amplifier. The offset current at an input of an amplifier can be reduced independent of an offset voltage at the input of the amplifier.

Abstract: Apparatus and methods are disclosed related to trimming an input offset current of an amplifier. One such apparatus can include auxiliary bipolar transistors connected in parallel with bases of respective bipolar transistors of an input stage of an amplifier. The auxiliary bipolar transistors can be biased such that the base currents of the auxiliary bipolar transistors compensate for a mismatch in base currents of the bipolar transistors of the input stage of an amplifier. The offset current at an input of an amplifier can be reduced independent of an offset voltage at the input of the amplifier.

Abstract: Apparatus and methods for reducing load-induced non-linearity in amplifiers are provided. In certain implementations, an amplifier includes a current mirror, a buffer circuit, and an output stage. The buffer circuit can have a relatively high current gain and a voltage gain about equal to 1. The buffer circuit can amplify a mirrored current generated by the current mirror and provide the amplified mirrored current to the output stage, thereby helping to balance or equalize currents in the current mirror and avoiding the impact of load-induced offset error.