US 8,395,446 B1 · Dual-mode amplifier

Abstract

Method and apparatus for amplification in an IC are described. A dual mode isolation amplifier having two modes of operation is provided. In the first mode of operation for a resistor-loaded differential transconductance with additional gain, a first switch circuit is placed in a substantially nonconductive state for electrically decoupling from a first current source node and a second current source node. A second switch circuit is placed in a substantially conductive state for electrically coupling a capacitor thereof to the first current source node and the second current source node. At high frequencies, a first resistance associated with the capacitor coupled in parallel with a resistive load is substantially reduced. The resistive load is coupled between the first current source node and the second current source node. The first resistance is reduced by approximating a short circuit by the capacitor during high-frequency operation.

Claims10

Dependent claims

A method for amplification, comprising:

providing a dual mode isolation amplifier having a first mode of operation and a second mode of operation;
in the first mode of operation, operating with a resistor-loaded differential transconductance with additional gain by:
deasserting a first high-pass control signal and asserting a second high-pass control signal;
placing a first switch circuit in a substantially nonconductive state for electrically decoupling from a first current source node and a second current source node;
placing a second switch circuit in a substantially conductive state for electrically coupling a capacitor thereof to the first current source node and the second current source node;
and
at high frequencies, substantially reducing a first resistance associated with the capacitor coupled in parallel with a resistive load, the resistive load coupled between the first current source node and the second current source node;
wherein the first resistance is reduced by approximating a short circuit by the capacitor during high-frequency operation.

5 more elements

An apparatus for amplification, comprising:

a isolation amplifier circuit;
a gain boost circuit coupled to the isolation amplifier circuit at a first current source node and a second current source node;
and
a current source module coupled to the isolation amplifier circuit and the gain boost circuit at the first current source node and the second current source node
wherein the gain boost circuit includes:
a first switch circuit coupled to receive a first high-pass control signal;
a second switch circuit coupled to receive a second high-pass control signal;
and
a first resistive load coupled in parallel with the first switch circuit and the second switch circuit between the first current source node and the second current source node;
wherein the second switch circuit includes a capacitor;
wherein the second high-pass control signal is complementary with respect to the first high pass signal;
and
wherein the first switch circuit and the second switch circuit are coupled in parallel with respect to one another between the first current source node and the second current source node.

10 more elements

Dependencies are inferred from the claim text.

Dual-mode amplifier

Life of this patent

Dual-mode amplifier

Life of this patent

Abstract

Claims10