Patent ID: 8416016

Claim:
A system for controlling a common-mode voltage and/or current of an H-bridge circuit, comprising: a modulator configured to receive an input signal, to modulate the received input signal, and to generate a digital signal having one of a plurality of voltage levels, the one voltage level selected based on the modulated received input signal, each of the plurality of voltage levels being assigned to a corresponding one of a plurality of logic states; an H-bridge controller configured to receive the digital signal and to generate control signals for controlling operation of the H-bridge circuit; an H-bridge circuit configured to receive the control signals and to operate based on the received control signals so as to output an analog signal to a load comprising a first terminal and a second terminal, wherein the H-bridge circuit comprises a plurality of states of operation including a first state of operation having a first variation and a second variation, a second state of operation, and a third state of operation, wherein the first and second variations are associated with different common-mode voltages of the H-bridge circuit, wherein the H-bridge circuit is configured to apply a first voltage to the first terminal and the second terminal of the load when the H-bridge circuit is in the first variation of the first state of operation, wherein the H-bridge circuit is configured to apply a second voltage to the first terminal and the second terminal of the load when the H-bridge circuit is in the second variation of the first state of operation, wherein the H-bridge circuit is configured to apply the first voltage to the first terminal of the load and the second voltage to the second terminal of the load when the H-bridge circuit is in the second state of operation, and wherein the H-bridge circuit is configured to apply the second voltage to the first terminal of the load and the first voltage to the second terminal of the load when the H-bridge circuit is in the third state of operation; and a common-mode error determination circuit configured to generate an error signal indicating at least one of an error of a common-mode voltage or an error of a common-mode current of the H-bridge circuit, wherein the H-bridge controller receives the error signal and generates the control signals based on the received digital signal and the received error signal, and wherein the H-bridge controller selectively controls the H-bridge circuit to operate in one of the first or second variations based on the error signal so as to reduce variations in at least one of an average of the common-mode voltage or an average of the common-mode current of the H-bridge circuit.