Variable output resistance in a playback path with closed-loop pulse-width modulation driver
AssigneeCirrus Logic, Inc.
InventorsTejasvi Das, Johann G. Gaboriau
Life of this patent
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Abstract
In accordance with embodiments of the present disclosure, an apparatus may include a signal path comprising a closed-loop analog pulse width modulator having a forward signal path and a feedback path, a variable resistor coupled to an output of the closed-loop analog pulse width modulator, and a control circuit configured to modify the variable resistor in order to modify an output impedance outside of the feedback path of the closed-loop analog pulse width modulator responsive to a condition for switching between a high output impedance mode and a low output impedance mode of the closed-loop analog pulse width modulator or vice versa.
Claims24
An apparatus, comprising:
- a signal path comprising a closed-loop analog pulse width modulator having a forward signal path and a feedback path and comprising a driver stage configured to drive an output voltage to an output of the apparatus;
- a variable resistor coupled between the driver stage of the closed-loop analog pulse width modulator and the output of the apparatus, such that the driver stage drives the output of the apparatus through the variable resistor;
- and
- a control circuit outside of the forward signal path and configured to modify the variable resistor in order to modify an output impedance outside of the feedback path of the closed-loop analog pulse width modulator responsive to a condition occurring within the signal path for switching between a high output impedance mode and a low output impedance mode of the closed-loop analog pulse width modulator or vice versa.
A method comprising, in a system comprising a signal path comprising a closed-loop analog pulse width modulator having a forward signal path and a feedback path and comprising a driver stage configured to drive an output voltage to an output of the system, and further having a variable resistor coupled between the driver stage of the closed-loop analog pulse width modulator and the output of the system, such that the driver stage drives the output of the system through the variable resistor:
- modifying, with a control circuit outside of the forward signal path, the variable resistor in order to modify an output impedance outside of the feedback path of the closed-loop analog pulse width modulator responsive to a condition occurring within the signal path for switching between a high output impedance mode and a low output impedance mode of the closed-loop analog pulse width modulator or vice versa.
Dependencies are inferred from the claim text.