National Instruments Corporation

Blake A Lindell

Christopher G Regier

Pablo Limon

Pablo E Limon-Garcia-Viesca

A method and apparatus for simultaneously testing a component at multiple frequencies is disclosed. A digital processing circuit may generate a digital representation of a signal having a plurality of sine waves, each having a unique frequency. The digital representation may be converted into an analog signal, and applied to a device under test (DUT). A first analog-to-digital converter (ADC) may be coupled to measure voltages across the DUT, while a second ADC may be coupled to measure currents through the DUT. Voltage and current signals received by the first and second ADCs, respectively, may be converted into first and second digital values. Voltage and current values at each unique frequency are determined from the first and second digital values. Using the voltage and current values for each unique frequency, a frequency response of the component (e.g., an impedance) over a range of frequencies may be determined.

Method and apparatus for simultaneously testing a component at multiple frequencies

An improved measurement system may include a source measure unit (SMU) capable of performing accurate low-level current measurements. Based on an SMU design that provides a controlled DC voltage source with precision current limiting and a controlled 0V (zero Volt) DC at the measurement terminal, an AC design may be implemented to establish the same (or very similar) conditions over a specified frequency range. Instead of controlling each digital-to-analog converter (DAC) at respective source terminals of the SMU as a respective DC output, each DAC may be controlled as a respective function generator with programmable frequency and continuously variable phase and amplitude. Off-the-shelf pipelined analog-to-digital converters (ADCs) may be used to monitor voltage, current and the voltage at the measurement terminal, and a Fourier transform may be used to obtain both the amplitude and relative phase measurements to be provided to respective control loops.

Growing community of inventors

Round Rock, TX, United States of America

Blake A Lindell