A system and method are provided for compensating for thermal drift of a probe device. The method includes monitoring a first temperature of a laser source in a sensor head that receives output electrical signals from a DUT and outputs corresponding optical signals; monitoring a second temperature of a photoreceiver in a probe interface that converts the optical signals to electrical test signals to input to the test instrument; calculating a first value of a first bias voltage using the first temperature; applying the first value of the first bias voltage to the laser source to compensate for thermal drift when the first temperature is within a first predefined temperature range; calculating a second value of a second bias voltage for the photoreceiver using the second temperature; and applying the second value of the second bias voltage to the photoreceiver to compensate for thermal drift when the second temperature is within a second predefined temperature range.

In one embodiment, a power supply comprises: a conversion circuit that outputs an output voltage at a first end of a cable; a remote voltage sensor measures a load delivered voltage from a second end of the cable; a control logic, wherein the power conversion circuit regulates the output voltage based on a signal from the control logic; a current sensor that measures current flow through the cable; and a resistance measurement circuit that computes a resistance of the cable as a function of the load delivered voltage, the current flow and the output voltage. The control logic regulates the load delivered voltage based on a voltage drop calculated utilizing the resistance. The control logic detects a change in the resistance of the cable based on the load delivered voltage and dynamically updates a value of the resistance for calculating the voltage drop when the change exceeds a tolerance.

In one embodiment, a power supply comprises: a conversion circuit that outputs an output voltage at a first end of a cable; a remote voltage sensor measures a load delivered voltage from a second end of the cable; a control logic, wherein the power conversion circuit regulates the output voltage based on a signal from the control logic; a current sensor that measures current flow through the cable; and a resistance measurement circuit that computes a resistance of the cable as a function of the load delivered voltage, the current flow and the output voltage. The control logic regulates the load delivered voltage based on a voltage drop calculated utilizing the resistance. The control logic detects a change in the resistance of the cable based on the load delivered voltage and dynamically updates a value of the resistance for calculating the voltage drop when the change exceeds a tolerance.

A signal converter circuit includes a frequency detection circuit configured to determine whether an external control signal is a PWM signal. A PWM frequency converter circuit is configured to detect, when a PWM signal is input, a duty cycle of the PWM signal and to generate a first digital signal. An AD converter is configured to generate a second digital signal based on an input DC voltage or a voltage attributable to a variable resistor to digital data using a maximum AD convertible input voltage as a duty cycle of 100%. An output signal generation circuit is configured to generate, based on the first or second digital signals output from the PWM frequency converter circuit or the AD converter, a PWM signal with a duty cycle based on that first or second digital signals.

A signal converter circuit includes a frequency detection circuit configured to determine whether an external control signal is a PWM signal. A PWM frequency converter circuit is configured to detect, when a PWM signal is input, a duty cycle of the PWM signal and to generate a first digital signal. An AD converter is configured to generate a second digital signal based on an input DC voltage or a voltage attributable to a variable resistor to digital data using a maximum AD convertible input voltage as a duty cycle of 100%. An output signal generation circuit is configured to generate, based on the first or second digital signals output from the PWM frequency converter circuit or the AD converter, a PWM signal with a duty cycle based on that first or second digital signals.

Systems and methods described herein provide a current sensor having fault detection circuitry configured to detect over-current and/or current faults corresponding to current through a conductor being greater than a predetermined level. The current sensor can include a shared signal path, a main signal path, and a fault detection signal path to perform both fault detection and current detection signal processing. The current sensor can include one or more magnetic field sensing elements configured to generate a magnetic field signal indicative of the current through the conductor, an analog-to-digital converter (ADC) configured to receive the magnetic field signal and convert the magnetic field signal into a digital signal, and a fault detector responsive to the digital signal to generate a fault signal indicative of the current through the conductor being greater than a predetermined level.

Systems and methods described herein provide a current sensor having fault detection circuitry configured to detect over-current and/or current faults corresponding to current through a conductor being greater than a predetermined level. The current sensor can include a shared signal path, a main signal path, and a fault detection signal path to perform both fault detection and current detection signal processing. The current sensor can include one or more magnetic field sensing elements configured to generate a magnetic field signal indicative of the current through the conductor, an analog-to-digital converter (ADC) configured to receive the magnetic field signal and convert the magnetic field signal into a digital signal, and a fault detector responsive to the digital signal to generate a fault signal indicative of the current through the conductor being greater than a predetermined level.

An apparatus for sensing distributed load currents provided by power gating circuit. The apparatus includes a power gating circuit including a set of bulk transistors coupled in series with a set of circuits between first and second voltage rails. The apparatus includes a current sensor with a first ring oscillator, a first frequency-to-code (FTC) converter, a second ring oscillator, a second FTC converter, and a subtractor. The first ring oscillator includes a first set of one or more inverters configured to receive a first voltage at a node between the power gating circuit and the first circuit, and a second set of one or more inverters configured to receive a second voltage at a second node between the power gating circuit and the second circuit. The first ring oscillator is configured to generate a signal including a frequency related to the voltage drops across the first and second sets of transistors.

An apparatus for sensing distributed load currents provided by power gating circuit. The apparatus includes a power gating circuit including a set of bulk transistors coupled in series with a set of circuits between first and second voltage rails. The apparatus includes a current sensor with a first ring oscillator, a first frequency-to-code (FTC) converter, a second ring oscillator, a second FTC converter, and a subtractor. The first ring oscillator includes a first set of one or more inverters configured to receive a first voltage at a node between the power gating circuit and the first circuit, and a second set of one or more inverters configured to receive a second voltage at a second node between the power gating circuit and the second circuit. The first ring oscillator is configured to generate a signal including a frequency related to the voltage drops across the first and second sets of transistors.

An eddy current displacement sensor includes devices or modules for digitizing and interpreting analog signals received from sensor coils. Periodic analog signals, such as sinusoidal or square wave signals, are sent to the coils with a suitable frequency. The output from the coils is then digitized using one or more analog-to-digital converters, at a sampling rate (frequency) that may be greater than that of the frequency of the input signal. The digitized output signals may then be processed to determine displacement of an object relative to the sensor coils, for example using magnitude and/or phase of the digital signals to estimate position. Digitizing the analog output signals directly, rather than only after such signals have been converted to DC signals, allows improvement in processing, as well as enabling flexibility in how the signals are used to estimate position.