Synchronous undersampling for high-frequency voltage and current measurements
First Claim
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1. An apparatus comprising:
- a power source configured to generate signals in response to a drive signal;
a sensor configured to measure a voltage and a current of the signals generated by the power source, and to generate sensor signals representative of the measured voltage and current;
a sampler configured to undersample the sensor signals synchronously with the drive signal that drives the power source, wherein the sampler comprises an A/D (analog-to-digital) converter and a sample clock, wherein the A/D converter is configured to control timing of samples in response to a timing reference provided by the sample clock,wherein the frequency of the sample clock is a scalar multiple of the frequency of the drive signal generated by a DDS (direct digital synthesizer);
a controller configured to receive the undersampled sensor signals, and to generate a frequency command signal that sets a frequency, wherein the controller comprises a DSP (digital signal processor);
a drive signal generator configured to generate the drive signal at the frequency set by the frequency command signal, wherein the drive signal generator comprises the DDS;
one or more digital mixers configured to convolve the undersampled signals from the sampler with a sine wave signal and a cosine wave signal; and
one or more CIC (cascade integrator comb) filters configured to decimate the convolved undersampled signals, thereby extracting from the undersampled signals information relating to magnitude and phase,wherein each one of the CIC filters are configured to generate one of an in-phase voltage signal, an out-of-phase voltage signal, an in-phase current signal, and an out-of-phase current signal.
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Abstract
A power source may generate signals (RF or microwave), when driven by a drive signal from a controller. A sensor may measure the voltage and current of the signals generated by the power source, and may generate sensor signals representative of the measured voltage and current. A sampler may be configured to undersample the sensor signals, synchronously with the drive signal that drives the power source. The sampling frequency may be a scalar multiple of the fundamental frequency of the sensor signals. At RF frequencies, either synchronous undersampling or synchronous oversampling may be performed. At microwave frequencies, synchronous undersampling may be performed.
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5 Claims
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1. An apparatus comprising:
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a power source configured to generate signals in response to a drive signal; a sensor configured to measure a voltage and a current of the signals generated by the power source, and to generate sensor signals representative of the measured voltage and current; a sampler configured to undersample the sensor signals synchronously with the drive signal that drives the power source, wherein the sampler comprises an A/D (analog-to-digital) converter and a sample clock, wherein the A/D converter is configured to control timing of samples in response to a timing reference provided by the sample clock, wherein the frequency of the sample clock is a scalar multiple of the frequency of the drive signal generated by a DDS (direct digital synthesizer); a controller configured to receive the undersampled sensor signals, and to generate a frequency command signal that sets a frequency, wherein the controller comprises a DSP (digital signal processor); a drive signal generator configured to generate the drive signal at the frequency set by the frequency command signal, wherein the drive signal generator comprises the DDS; one or more digital mixers configured to convolve the undersampled signals from the sampler with a sine wave signal and a cosine wave signal; and one or more CIC (cascade integrator comb) filters configured to decimate the convolved undersampled signals, thereby extracting from the undersampled signals information relating to magnitude and phase, wherein each one of the CIC filters are configured to generate one of an in-phase voltage signal, an out-of-phase voltage signal, an in-phase current signal, and an out-of-phase current signal. - View Dependent Claims (2, 3, 4, 5)
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Specification