Abstract: A method for measuring the impedance of a DUT having a capacitance of less than 1 pF includes applying a voltage or current signal to the DUT, the voltage or current signal including an AC component having a non-zero frequency of less than 1 kHz; monitoring a current or voltage signal, respectively, through the DUT in response to the voltage or current signal; digitizing the voltage signal and the current signal synchronously; and calculating the impedance from the digitized voltage and current signals.

Abstract: A circuit structured to drive an isolated high speed voltage metal-oxide-semiconductor field-effect transistor (MOSFET) switch, including a first MOSFET and a second MOSFET configured to operate as a switch, a capacitor, a charging component in parallel with the capacitor, a first switch in series with the charging component, and a second switch in parallel with the charging component and the capacitor. The stored voltage in the capacitor is sent to the gates of the first MOSFET and the second MOSFET when a second switch is open and a first switch is closed.

Abstract: Bias tees, according to certain embodiments of the present invention, include switches in the AC signal path, the DC signal path, or both, to improve the capability of the bias tees to be used for high impedance AC measurement, low current DC measurement, or both. Optical control of the switches, as well as control of the switches using a DC bias present within the AC signal input to the bias tee, is described. Including a set of diodes into the DC signal path, rather than a switch, provides enhanced capability of the bias tee to be used for high impedance AC measurements.

Abstract: A system may include two input terminals, e.g., HI and LO, and a floating circuit that is physically separate from the input terminals and includes a gain amplifier. The floating circuit can be surrounded by a conductive enclosure that is electrically connected to the second input terminal. The floating circuit can further switch between input signals received from the first and second input terminals to the gain amplifier and the floating circuit ground.

Abstract: An isolated DC-to-DC switching power supply includes an isolation transformer having a magnetic core, a first winding around the magnetic core, a first winding-shield around the magnetic core, a second winding-shield within the first winding-shield, and a second winding within the second winding-shield. There is no direct coupling between the first winding and the second winding since the second winding is enclosed within the second winding-shield and the second winding-shield is enclosed within the first winding-shield.

Abstract: An active shunt source-measure unit (SMU) circuit can include an SMU or power supply having an active shunt circuit that is integrated with the current measuring sub-circuit of the SMU circuit. The active shunt circuit may be active during voltage sourcing of the SMU circuit and deactivated during current sourcing of the SMU circuit.

Abstract: An RF testing method and system by which a DC measurement pathway can also act like a properly terminated RF pathway. Achieving this requires that the output HI, LO, and Sense HI conductors are terminated in a frequency selective manner such that the terminations do not affect the SMU DC measurements. Once all SMU input/output impedances are controlled, as well as properly terminated to eliminate reflections, the high-speed devices will no longer oscillate during device testing, so long as the instruments maintain a high isolation from instrument-to-instrument (separate instruments are used on the gate and drain, or on the input and output of the device). The output of HI, LO and Sense HI conductors are coupled to various nodes of the DUT via three triaxial cables, the outer shieldings of which are coupled to each other and to an SMU ground.

Abstract: A device with low dielectric absorption includes a printed circuit board (PCB), a component connection area including a first conductor layered on a top surface of the component connection area and a second conductor layered on a bottom surface of the component connection area, an aperture surrounding the component connection area, a low-leakage component connecting the component connection area to the PCB across the aperture, and a guard composed of a third conductor at least substantially surrounding the aperture on a top surface of the PCB and a fourth conductor at least substantially surrounding the aperture on a bottom surface of the PCB.

Abstract: A circuit can include operational amplifier having a first input, a second input, and an output, first and second resistors in series between the output of the op-amp and a ground, and multiple switches configurable to toggle the circuit between a positive phase and a negative phase.

Abstract: A switch protection circuit includes a discharging circuit and, optionally, a clamping circuit. The discharge circuit operates prior to the switch completing the switching action to discharge capacitance from a signal line of a cable connected to a device under test to a ground voltage. When not discharging, the discharge circuit presents low leakage to a measurement circuit so as not to interfere with such measurement. If present, the clamping circuit clamps a signal line of the cable to a guard structure of the cable so that the discharge circuit can couple both the signal line and the guard structure to ground. The protection circuit operates without significantly worsening low current performance of the measurement instrument.

Abstract: A circuit can include operational amplifier having a first input, a second input, and an output, first and second resistors in series between the output of the op-amp and a ground, and multiple switches configurable to toggle the circuit between a positive phase and a negative phase.

Abstract: A method for compensating for a dielectric absorption effect in a measurement configuration during measurements by an instrument having measurement terminals includes providing a feedback loop in the instrument, the loop having a gain adjustment and a simulation impedance and being adapted to provide a signal counter to the dielectric absorption at the measurement terminals; applying a transient calibration signal to the test terminals for at least two values of the gain adjustment; measuring a response to the calibration signal for each of the at least two values; and determining an operating value of the gain adjustment based on the measured responses. The operating value is used for subsequent measurements by the instrument, the simulation impedance modeling the dielectric absorption characteristics of the measurement configuration.

Abstract: An isolated DC-to-DC switching power supply includes an isolation transformer having a magnetic core, a first winding around the magnetic core, a first winding-shield around the magnetic core, a second winding-shield within the first winding-shield, and a second winding within the second winding-shield. There is no direct coupling between the first winding and the second winding since the second winding is enclosed within the second winding-shield and the second winding-shield is enclosed within the first winding-shield.

Abstract: A measurement instrument for measuring the impedance of a device under test (DUT) includes a first source of either a voltage or a current and a second source of either a voltage or a current, wherein the first source is connectable in a first feedback relationship with the DUT and the second source is connectable in a second feedback relationship with both the DUT and the first source. The first and second sources are operated respectively as a current source responsive to the current through the DUT and a voltage source responsive to the voltage across the DUT or operated respectively as a voltage source responsive to the voltage across the DUT and a current source responsive to the current through the DUT. The second feedback relationship has a narrower bandwidth than the first feedback relationship. The resulting voltage across the DUT and the current through the DUT establish the measured impedance of the DUT.

Abstract: A system can include a device under test (DUT) having a DUT voltage, a cable connected to the DUT, the cable having a cable inductance, and a power supply configured as a current source to provide a wide bandwidth voltage source to the DUT, wherein the DUT voltage is independent of the cable inductance.

Abstract: A system may include two input terminals, e.g., HI and LO, and a floating circuit that is physically separate from the input terminals and includes a gain amplifier. The floating circuit can be surrounded by a conductive enclosure that is electrically connected to the second input terminal. The floating circuit can further switch between input signals received from the first and second input terminals to the gain amplifier and the floating circuit ground.

Abstract: A method for verifying the adjustment for the purpose of calibration of an impedance meter having at least a first and a second measurement range includes measuring within the first range a first measured value of a test impedance; measuring within the second range a second measured value of the test impedance; and comparing the first and second measured values to verify the calibration of the impedance meter.

Abstract: An RF testing method and system by which a DC measurement pathway can also act like a properly terminated RF pathway. Achieving this requires that the output HI, LO, and Sense HI conductors are terminated in a frequency selective manner such that the terminations do not affect the SMU DC measurements. Once all SMU input/output impedances are controlled, as well as properly terminated to eliminate reflections, the high-speed devices will no longer oscillate during device testing, so long as the instruments maintain a high isolation from instrument-to-instrument (separate instruments are used on the gate and drain, or on the input and output of the device). The output of HI, LO and Sense HI conductors are coupled to various nodes of the DUT via three triaxial cables, the outer shieldings of which are coupled to each other and to an SMU ground.

Abstract: A high voltage protection module can include a housing having two chambers and a wall separating the chambers. The wall can have a hole through which a conductive element can pass to electrically couple an input with an output. The conductive element can be configured to break or fuse with the hole responsive to a high voltage event at the input.

Abstract: A method for measuring the impedance of a DUT having a capacitance of less than 1 pF includes applying a voltage or current signal to the DUT, the voltage or current signal including an AC component having a non-zero frequency of less than 1 kHz; monitoring a current or voltage signal, respectively, through the DUT in response to the voltage or current signal; digitizing the voltage signal and the current signal synchronously; and calculating the impedance from the digitized voltage and current signals.