Biasing circuit for a microelectromechanical acoustic transducer and related biasing method
AssigneeSTMicroelectronics S.r.I.
InventorsFilippo David, Alessandro Gasparini
Life of this patent
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Abstract
A biasing circuit for an acoustic transducer is provided with: a voltage-booster stage, which supplies, on a biasing terminal, a boosted voltage for biasing a first terminal of the acoustic transducer; and filtering elements, set between the biasing terminal and the acoustic transducer, for filtering disturbances on the boosted voltage. The biasing circuit is further provided with switches, which can be actuated so as to connect the first terminal to the biasing terminal of the voltage-booster stage, directly during a start-up step of the biasing circuit, and through the filtering elements at the end of the start-up step.
Claims28
A biasing circuit for an acoustic transducer, comprising:
- a biasing terminal configured to receive from a voltage-booster stage a boosted voltage for biasing a first terminal of said acoustic transducer;
- a filter coupled to the biasing terminal, configured to be set between said biasing terminal and said acoustic transducer, and configured to implement filtering of disturbances on said boosted voltage;
- and
- a first switch configured to provide a current path between said biasing terminal and said first terminal during a start-up step of said biasing circuit, and configured to allow the filter to filter the disturbances once said start-up step has terminated.
An electronic device, comprising:
- an acoustic transducer;
- a voltage-booster stage configured to provide a boosted voltage;
- and
- a biasing circuit coupled to the acoustic transducer and configured to bias said acoustic transducer, the biasing circuit including:
- a biasing terminal configured to receive the boosted voltage from the voltage-booster stage;
- a filter coupled between the biasing terminal and the first terminal of said acoustic transducer, and configured to implement filtering of disturbances on said boosted voltage;
- and
- a first switch configured to provide a current path between said said biasing terminal and the first terminal during a start-up step of said biasing circuit, and configured to allow the filter to filter the disturbances once said start-up step has terminated.
The device according to 19, wherein said driving stage has a circuit structure with substantially symmetrical first and second sides, the first being coupled to the output of said driving stage and including:
- a current-mirror stage coupled to said output and configured to generate a biasing current;
- and
- an output branch including a parallel circuit of an output transistor and a resistive network and configured to receive said boosted voltage;
- said current-mirror stage being configured to be alternately enabled and disabled by said timing signal, said resistive network being configured to generate said voltage drop with respect to said boosted voltage and said low level of said control signal in response to the biasing current being provided to the resistive network by the current-mirror stage when the current-mirror stage is enabled by the timing signal, and said output transistor being configured to bring said control signal at said output to said boosted voltage in response to the current-mirror stage being disabled by the timing signal.
A biasing method for an acoustic transducer, comprising:
- generating, on a biasing terminal, a boosted voltage for biasing a first terminal of said acoustic transducer;
- short-circuiting said first terminal to said biasing terminal, set at said boosted voltage, during a start-up step of said biasing;
- and
- stopping the short-circuiting and filtering, via a filter, disturbances on said boosted voltage at an end of said start-up step.
Dependencies are inferred from the claim text.