A frequency variable oscillator generates a clock having a frequency according to a control signal. A reference current source generates a reference current. A path selector distributes the reference current to a first path and a second path in a time-sharing manner in synchronization with the clock. An F/V conversion circuit includes a capacitor connected to the first path, and charges or discharges the capacitor with the reference current and generates a detection voltage. The reference voltage source includes a resistor connected to the second path, and outputs a reference voltage according to a voltage across the resistor. A feedback circuit adjusts a control signal so that the detection voltage approaches the reference voltage.

A security method for monitoring an optical module and a three-dimensional sensor using the same apply electromagnetic induction to the three-dimensional sensor to monitor the optical module and a light source module. Two inductive coils corresponding to each other are arranged on the light source module and the optical module. An alternative current is inputted to one of the inductive coils and another of the inductive coils generates an inductive current. The value of the inductive current is continuously detected. When the value of the inductive current varies, the abnormality of the optical module is determined to shut down the light source module, thereby completing the security mechanism of the three-dimensional sensor.

The present disclosure relates to a system comprising: a MEMS capacitive transducer comprising a first electrode and a second electrode; integrator circuitry; and test circuitry. The MEMS capacitive transducer forms part of a negative feedback path of the integrator circuitry, and the test circuitry is operable to selectively apply one or more current sources to an input of the integrator circuitry based on a signal at an output of the integrator so as to generate a periodic signal at the output of the integrator circuitry. A frequency of the periodic signal is at least partially dependent upon a capacitance of the MEMS capacitive transducer. The system is further operative to determine a parameter indicative of the frequency of the periodic signal and to estimate the capacitance of the MEMS capacitive transducer based on the parameter indicative of the frequency of the periodic signal.

The present disclosure relates to a system comprising: a MEMS capacitive transducer comprising a first electrode and a second electrode; integrator circuitry; and test circuitry. The MEMS capacitive transducer forms part of a negative feedback path of the integrator circuitry, and the test circuitry is operable to selectively apply one or more current sources to an input of the integrator circuitry based on a signal at an output of the integrator so as to generate a periodic signal at the output of the integrator circuitry. A frequency of the periodic signal is at least partially dependent upon a capacitance of the MEMS capacitive transducer. The system is further operative to determine a parameter indicative of the frequency of the periodic signal and to estimate the capacitance of the MEMS capacitive transducer based on the parameter indicative of the frequency of the periodic signal.

The present disclosure relates to a system comprising: a MEMS capacitive transducer comprising a first electrode and a second electrode; integrator circuitry; and test circuitry. The MEMS capacitive transducer forms part of a negative feedback path of the integrator circuitry, and the test circuitry is operable to selectively apply one or more current sources to an input of the integrator circuitry based on a signal at an output of the integrator so as to generate a periodic signal at the output of the integrator circuitry. A frequency of the periodic signal is at least partially dependent upon a capacitance of the MEMS capacitive transducer. The system is further operative to determine a parameter indicative of the frequency of the periodic signal and to estimate the capacitance of the MEMS capacitive transducer based on the parameter indicative of the frequency of the periodic signal.

The present disclosure relates to a system comprising: a MEMS capacitive transducer comprising a first electrode and a second electrode; integrator circuitry; and test circuitry. The MEMS capacitive transducer forms part of a negative feedback path of the integrator circuitry, and the test circuitry is operable to selectively apply one or more current sources to an input of the integrator circuitry based on a signal at an output of the integrator so as to generate a periodic signal at the output of the integrator circuitry. A frequency of the periodic signal is at least partially dependent upon a capacitance of the MEMS capacitive transducer. The system is further operative to determine a parameter indicative of the frequency of the periodic signal and to estimate the capacitance of the MEMS capacitive transducer based on the parameter indicative of the frequency of the periodic signal.

A method is provided for testing switch signals of an inverter of an electric machine of a drive system of a motor vehicle. The electric machine is controlled via a pulse-width modulation generated by a control unit using a target duty cycle and a triangular-waveform voltage sequence. An actual duty cycle of a current pulse-width modulation is continuously ascertained from the switch signals and compared with the target duty cycle of the control unit.

A method is provided for testing switch signals of an inverter of an electric machine of a drive system of a motor vehicle. The electric machine is controlled via a pulse-width modulation generated by a control unit using a target duty cycle and a triangular-waveform voltage sequence. An actual duty cycle of a current pulse-width modulation is continuously ascertained from the switch signals and compared with the target duty cycle of the control unit.

Aspects of the present disclosure include a frequency-to-current (F2I) circuit and systems, methods, devices, and other circuits related thereto. The F2I circuit is implemented with a delta-modulator-based control loop to settle and maintain an operating point on a bias node. The control loop provides an integral of an output of a comparator, and the comparator compares it to a self-built voltage reference. Upon powering on the circuit, an integrator in the control loop starts to integrate the charge on both a bias voltage and an internal voltage to provide a settling process for the internal voltage to approximate the reference voltage and for the bias voltage to approximate a predetermined operating point of the bias node. After the circuit has settled, the comparator's output charge toggles and the internal voltage and bias voltage become sawtooth-like waveforms at the reference voltage and operating points, respectively.

Aspects of the present disclosure include a frequency-to-current (F2I) circuit and systems, methods, devices, and other circuits related thereto. The F2I circuit is implemented with a delta-modulator-based control loop to settle and maintain an operating point on a bias node. The control loop provides an integral of an output of a comparator, and the comparator compares it to a self-built voltage reference. Upon powering on the circuit, an integrator in the control loop starts to integrate the charge on both a bias voltage and an internal voltage to provide a settling process for the internal voltage to approximate the reference voltage and for the bias voltage to approximate a predetermined operating point of the bias node. After the circuit has settled, the comparator's output charge toggles and the internal voltage and bias voltage become sawtooth-like waveforms at the reference voltage and operating points, respectively.