Reference signal generator circuit for an analog-to-digital converter of a microelectromechanical acoustic transducer, and corresponding method
First Claim
1. A reference signal generator circuit, comprising:
- a first reference terminal and a second reference terminal, the first reference terminal structured to receive a first reference signal;
a filtering circuit arranged between the first reference terminal and the second reference terminal, the filtering circuit structured to filter a disturbance on the first reference signal and to supply at output on the second reference terminal a filtered reference signal, the filtering circuit including a first diode element and a first switch circuit each coupled between the first and second reference terminals;
a control circuit structured to actuate the first switch circuit in a first operative condition of low-impedance conduction in which the first switch circuit constitutes a low-impedance coupling between the first reference terminal to the second reference terminal during startup of the reference signal generator circuit and in a second operative condition of high impedance in which the first switch circuit acts as a second diode element in antiparallel with the first diode element and provides a high-impedance connection between the first reference terminal and the second reference terminal once startup is terminated.
1 Assignment
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Accused Products
Abstract
A reference signal generator circuit for an analog-to-digital converter, the circuit having a signal-generation stage to generate a first reference signal on a first reference terminal, and a filtering circuit arranged between the generator stage and the analog-to-digital converter to determine a filtering of disturbance present on the first reference signal and supply at output on a second reference terminal a second filtered reference signal, the filtering circuit having a switching circuit to connect the first reference terminal to the second reference terminal directly during startup of the reference signal generator circuit and then through the filtering circuit once the startup step is terminated.
20 Citations
18 Claims
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1. A reference signal generator circuit, comprising:
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a first reference terminal and a second reference terminal, the first reference terminal structured to receive a first reference signal; a filtering circuit arranged between the first reference terminal and the second reference terminal, the filtering circuit structured to filter a disturbance on the first reference signal and to supply at output on the second reference terminal a filtered reference signal, the filtering circuit including a first diode element and a first switch circuit each coupled between the first and second reference terminals; a control circuit structured to actuate the first switch circuit in a first operative condition of low-impedance conduction in which the first switch circuit constitutes a low-impedance coupling between the first reference terminal to the second reference terminal during startup of the reference signal generator circuit and in a second operative condition of high impedance in which the first switch circuit acts as a second diode element in antiparallel with the first diode element and provides a high-impedance connection between the first reference terminal and the second reference terminal once startup is terminated. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A reference signal generator circuit, comprising:
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a first reference terminal and a second reference terminal; a signal-generation stage coupled to the first reference terminal; a filtering circuit coupled between the first reference terminal and the second reference terminal; a switch circuit coupled to the first and second reference terminals and in parallel with the filtering circuit; and a buffer circuit coupled to the second reference terminal and configured to be coupled to the capacitive load, the buffer circuit configured to drive the capacitive load;
the buffer circuit including;a single-stage amplifier in voltage-follower configuration and having a non-inverting input coupled to the filtering circuit, and a compensation capacitor coupled to an output terminal of the single-stage amplifier and configured to be coupled in parallel to the capacitive load. - View Dependent Claims (8, 9, 10, 11, 12)
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13. An electronic device, comprising:
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an analog-to-digital converter having an input terminal and an input stage that includes a capacitive load; a reference signal generator circuit structured to supply a filtered reference signal to the input terminal of the analog-to-digital converter, the reference signal generator circuit including; a first reference terminal and a second reference terminal; a signal-generation stage structured to generate a first reference signal on the first reference terminal; a filtering circuit coupled between the first reference terminal and the second reference terminal and further coupled to the analog-to-digital converter, the filtering circuit configured to filter a disturbance on the first reference signal and to supply at output on the second reference terminal a filtered reference signal; and a switch circuit coupled to the first reference terminal and to the second reference terminal; and a buffer circuit having an output terminal coupled to the analog-to-digital converter and structured to drive the capacitive load, the buffer circuit including a single-stage amplifier in voltage-follower configuration and having a non-inverting input structured to receive the filtered reference signal, and a compensation capacitor coupled to the output terminal of the buffer circuit and further coupled in parallel to the capacitive load. - View Dependent Claims (14, 15, 16)
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17. A circuit, comprising:
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first and second nodes; a signal generator structured to generate a first reference signal at the first node; a filter circuit coupled to the first node and structured to receive the first reference signal and to generate a filtered reference signal at the second node; a first transistor coupled between the first and second nodes and structured to be actuated in a first operative condition of low-impedance conduction between the first and second nodes and in a second operative condition of high impedance conduction between the first and second nodes, the first transistor including a control terminal; a second transistor in diode configuration coupled between the first and second nodes, the second transistor including a control terminal; and a switch circuit coupled to the first and second nodes and structured to selectively connect the signal generator directly to the second node to bypass the filter circuit, and to connect the filter circuit to the first and second nodes, the switch circuit including; a control circuit coupled to the first transistor and structured to bias alternatingly the control terminal of the first transistor with a ground signal or the first reference signal to provide alternatingly the low-impedance conduction or the high-impedance conduction between the first and second nodes; a comparator having a first input terminal configured to receive the filtered reference signal and a second input terminal configured to receive a comparison signal correlated to the first reference signal to define a threshold, and an output terminal, the comparator configured to supply on the output terminal a result of a comparison between the comparison signal and the filtered reference signal; and a logic block having a first input terminal, a second input terminal, and an output terminal, the logic block structured to receive a first control signal on the first input terminal, to receive the result from the comparator on the second input terminal, and to supply on the output terminal a second control signal to drive the first transistor in low-impedance conduction when the filtered reference signal drops below the threshold. - View Dependent Claims (18)
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Specification