Amplifiers
AssigneeCirrus Logic, Inc.
InventorJohn P. Lesso
Life of this patent
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Abstract
This application relates to an amplifier selectively operable in first or second modes. The first mode is a BTL mode with first and second output drivers (103p, 103n) both active to generate respective driving signals that vary with an input signal. The second mode is an SE mode, where the first output driver (103p) is active to generate a driving signal at and the output of the second driver (103n) is held constant. A controller (201) selectively controls the mode based on an indication of output signal amplitude. In the first mode, a ratio of magnitude of the two driving signals varies with the indication of output signal amplitude, i.e. the magnitudes of the two driving signals may vary so as to be not equal.
Claims20
An amplifier circuit for generating an output signal between first and second output nodes based on a received input signal, the amplifier circuit comprising:
- first and second output drivers;
- and
- a controller for selectively controlling the amplifier circuit in a first mode or a second mode based on an indication of output signal amplitude;
- wherein:
- in the first mode the first and second output drivers are both active to generate respective first and second driving signals that each vary with the input signal at the first and second output nodes respectively;
- and
- in the second mode the first output driver is active to generate a first driving signal at the first output node that varies with the input signal and the second driver is controlled to maintain the second output node at a constant voltage;
- and wherein in the second mode, the second output driver is operated in a mode with a lower power consumption than in the first mode.
An amplifier circuit for generating an output signal between first and second output nodes based on a received input signal, the amplifier circuit comprising:
- first and second output drivers;
- and
- a controller for selectively controlling the amplifier circuit in a first mode or a second mode based on an indication of output signal amplitude;
- wherein:
- in the first mode the first and second output drivers are both active to generate respective first and second driving signals that each vary with the input signal at the first and second output nodes respectively;
- and
- in the second mode the first output driver is active to generate a first driving signal at the first output node that varies with the input signal and the second driver is controlled to maintain the second output node at a constant voltage;
- and wherein in the first mode a ratio of magnitude of the second driving signal compared to magnitude of the first driving signal varies with the indication of output signal amplitude.
An amplifier circuit comprising:
- a first signal path comprising a first amplifier;
- a second signal path comprising a second amplifier;
- and
- a controller for selectively operating the circuit in:
- a first mode, in which both the first amplifier and second amplifier are active to drive first and second output nodes with respective first and second driving signals that each vary with the input signal;
- and
- a second mode in which the first amplifier is active to drive the first output node with the first driving signal that varies with the input signal and the second output node is held at a constant voltage by the second output driver;
- wherein the controller operates in the first mode when an indication of output signal amplitude is within a first range and where the controller controls a gain of the second path to reduce with reducing indication of output signal amplitude over said first range whilst maintain or increasing a gain of the first path.
Dependencies are inferred from the claim text.