US 12,422,536 B2Granted

Method of operating electro-acoustic transducers, corresponding circuit and device

AssigneeSTMicroelectronics S.r.l.

InventorsFrancesca Carminati, Marco Passoni, Beatrice Rossi, Diego Carrera, Pasqualina Fragneto

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Abstract

A method of operating a PMUT electro-acoustical transducer, the method comprising: applying over an excitation interval to the transducer an excitation signal which is configured to emit corresponding ultrasound pulses towards a surrounding space, acquiring at a receiver reflected ultrasound pulses as reflected in said surrounding space, generating a reference echo signal, performing a cross-correlation of said acquired received ultrasound pulses with said reference echo signal, performing a measurement based on the cross-correlation results, in particular a measurement of the time of flight of the ultrasound pulses, wherein said reference echo is obtained by finding an oscillation frequency of the transmitter on the basis of a transmitter ringdown signal, finding an oscillation frequency of the receiver on the basis of a receiver ringdown signal, performing a frequency tuning respectively on the transmitter and the receiver on the basis of said respective oscillation frequencies, then sweeping an input frequency of the transmitter to find a frequency of the maximum displacement in the ringdown signal, performing a frequency tuning of the receiver at said frequency of the maximum displacement in the ringdown signal of the transmitter.

Claims18

Dependent claims

A method, comprising:

applying, over an excitation interval to a transmitter of an electro-acoustical transducer, an excitation signal that is configured to emit corresponding ultrasound pulses from the transmitter and towards a surrounding space;
acquiring, at a receiver of the electro-acoustical transducer, reflected ultrasound pulses that are reflected in the surrounding space;
generating a reference echo signal, the generating of the reference echo signal including:
determining an oscillation frequency of the transmitter based on a transmitter ringdown signal;
determining an oscillation frequency of the receiver based on a receiver ringdown signal;
performing frequency tuning on the transmitter and the receiver based on the oscillation frequency of the transmitter and the oscillation frequency of the receiver, respectively;
determining a frequency of a maximum displacement in the transmitter ringdown signal by sweeping an input frequency of the transmitter;
performing a frequency tuning of the receiver at the frequency of the maximum displacement in the transmitter ringdown signal;
exciting, with a high voltage corresponding to a non-linear operation zone, the transmitter at the oscillation frequency of the transmitter, and acquiring a corresponding ringdown;
determining a period from the corresponding ringdown;
feeding a trained neural network with a period curve, series parameters of a Butterworth-Van Dyke (BVD) model, and an initial value of the corresponding ringdown;
determining one or more non-linear parameters of the transmitter with the trained neural network;
and
predicting the reference echo signal based on the one or more non-linear parameters;
performing a cross-correlation of the reflected ultrasound pulses with the reference echo signal;
and
performing a measurement based on the cross-correlation, the measurement including a time of flight of the ultrasound pulses.

14 more elements

A circuit, comprising:

an electro-acoustical transducer configured to transmit ultrasound pulses, and receive reflected ultrasound pulses;
exciter circuitry configured to apply, to the electro-acoustical transducer, an excitation signal over an excitation interval;
and
processing circuitry configured to;
generate a reference echo signal, wherein, for the generation of the reference echo signal,
the exciter circuitry excites, with a high voltage corresponding to a non-linear operation zone, the electro-acoustical transducer at an oscillation frequency of a transmitter of the electro-acoustical transducer, and the processing circuitry acquires a corresponding ringdown,
the processing circuitry determines a period from the corresponding ringdown;
the processing circuitry feeds a trained neural network with a period curve, series parameters of a Butterworth-Van Dyke (BVD) model, and an initial value of the corresponding ringdown;
the processing circuitry determines one or more non-linear parameters of the transmitter with the trained neural network;
and
the processing circuitry predicts the reference echo signal based on the one or more non-linear parameters;
perform a cross-correlation of the reflected ultrasound pulses with the reference echo signal;
and
perform a measurement based on the cross-correlation, the measurement including a time of flight of the ultrasound pulses.

11 more elements

A device comprising:

an electro-acoustical transducer configured to transmit ultrasound pulses, and receive reflected ultrasound pulses;
exciter circuitry configured to apply, to the electro-acoustical transducer, an excitation signal over an excitation interval;
and
processing circuitry configured to:
generate a reference echo signal, wherein, for the generation of the reference echo signal,
the exciter circuitry excites, with a high voltage corresponding to a non-linear operation zone, the electro-acoustical transducer at an oscillation frequency of a transmitter of the electro-acoustical transducer, and the processing circuitry acquires a corresponding ringdown,
the processing circuitry determines a period from the corresponding ringdown;
the processing circuitry feeds a trained neural network with a period curve, series parameters of a Butterworth-Van Dyke (BVD) model, and an initial value of the corresponding ringdown;
the processing circuitry determines one or more non-linear parameters of the transmitter with the trained neural network;
and
the processing circuitry predicts the reference echo signal based on the one or more non-linear parameters;
perform a cross-correlation of the reflected ultrasound pulses with the reference echo signal;
and
perform a measurement based on the cross-correlation, the measurement including a time of flight of the ultrasound pulses,
wherein the device is an obstacle detection device, a volume measurement device, a gesture recognition device, a flow metering device, or a device relying on time-of-flight measurements of sound waves.

12 more elements

Dependencies are inferred from the claim text.