Energy efficient clip limiting voltage controlled amplifier
AssigneeRGB Systems, Inc.
InventorEric Mendenhall
Life of this patent
Estimating the term…
Abstract
A voltage controlled amplifier with an amplitude limiting circuit, such as a clip limiter, that is separate from the signal path on which the input signal is received by a power amplifier can reduce both noise and power expenditure of the voltage controlled amplifier. The amplitude limiting circuit can include a transistor network that is controlled by a pair of utility operational amplifiers. These utility amplifiers may use less current than the audio amplifier of the voltage controlled amplifier. Further, the transistor network can be deactivated when a signal supplied to the voltage controlled amplifier is below a clipping or other voltage limiting threshold.
Claims22
A voltage controlled amplifier, comprising:
- a power amplifier in a primary signal path, the power amplifier configured to receive an input signal transmitted along the primary signal path and to amplify the input signal;
- and
- an amplitude limiting circuit in a secondary signal path that is configured to limit the gain of the power amplifier when active, wherein the amplitude limiting circuit comprises:
- a first differential transistor pair of a first type;
- a second differential transistor pair of a second type, wherein the first differential transistor pair and the second differential transistor pair are configured to attenuate the input signal provided to the power amplifier;
- and
- a control circuit configured to control operation of the first differential transistor pair and the second differential transistor pair based at least in part on a control signal, wherein the control signal indicates whether to attenuate the input signal, wherein the control circuit comprises an operational amplifier.
(canceled)
An audio amplifier system comprising:
- a power supply configured to power one or more voltage controlled amplifiers;
- and
- a voltage controlled amplifier of the one or more voltage controlled amplifiers, the voltage controlled amplifier comprising:
- a power amplifier in a first signal path, the power amplifier configured to receive an input signal transmitted along the first signal path and to amplify the input signal;
- and
- an amplitude limiting circuit in a second signal path that is configured to limit the gain of the power amplifier when in a first mode, wherein the amplitude limiting circuit comprises:
- a first differential transistor pair of a first type;
- a second differential transistor pair of a second type, wherein the first differential transistor pair and the second differential transistor pair are configured to attenuate the input signal provided to the power amplifier;
- and
- a control circuit configured to control operation of the first differential transistor pair and the second differential transistor pair based at least in part on a control signal corresponding to the first mode or a second mode, wherein a quiescent current of the amplitude limiting circuit is substantially less when operating in the second mode than when operating in the first mode.
(canceled)
A method of controlling a voltage controlled amplifier, the method comprising:
- obtaining a voltage measurement at a summing point of a power amplifier of the voltage controlled amplifier;
- determining that the voltage measurement satisfies a clipping threshold;
- providing a control signal to a control input of a voltage limiting circuit of the voltage controlled amplifier, the control signal based at least in part on the voltage measurement;
- providing a first output signal of the voltage limiting circuit to a non-inverting input of the power amplifier;
- and
- providing a second output signal of the voltage limiting circuit to an inverting input of the power amplifier, wherein the first output signal and the second output signal causes an amplitude of an output of the power amplifier to be reduced.
Dependencies are inferred from the claim text.