Real-equivalent-time oscilloscope and wideband real-time spectrum analyzer

Patent metadata

Field	Value
Publication number	US-12574039-B2
Application number	US-202418591468-A
Country	US
Kind code	B2
Filing date	Feb 29, 2024
Priority date	Mar 14, 2023
Publication date	Mar 10, 2026
Grant date	Mar 10, 2026

Abstract

A test and measurement instrument includes one or more channels to receive a signal under test, each channel comprising an input port, a filter, and a sampler, at least one analog-to-digital converter (ADC), the at least one ADC having two pipes connected to the sampler of one of the one or more channels, the at least one ADC to produce digital samples of the signal at a sample rate, and one or more processors configured to execute code that causes the one more processors to acquire a spectrum of the digital samples for each pipe in the at least one ADC, and use the spectrums of the digital samples for each pipe in the at least one ADC to reconstruct the spectrum of the signal under test. A method of operating a test and measurement instrument, and a method a method of calibrating a test and measurement instrument is included.

First claim

The invention claimed is:

1 . A test and measurement instrument, comprising:
one or more channels to receive a signal under test, each channel comprising an input port, a filter, and a sampler; at least one analog-to-digital converter (ADC), the at least one ADC having two pipes connected to the sampler of one channel of the one or more channels, the at least one ADC to produce digital samples of the signal under test at a sample rate; and one or more processors configured to execute code that causes the one more processors to:
acquire a spectrum of the digital samples for each pipe in the at least one ADC; and
use the spectrums of the digital samples for each pipe in the at least one ADC to reconstruct the spectrum of the signal under test.

2 . The test and measurement instrument as claimed in claim 1 , wherein the input port comprises one of an electrical port, an optical port, and a wireless port.

3 . The test and measurement instrument as claimed in claim 1 , wherein the code that causes the one or more processors to acquire a spectrum of the digital samples for each pipe comprises performing a Fast Fourier Transform (FFT) of the digital samples for each pipe.

4 . The test and measurement instrument as claimed in claim 1 , wherein the filter comprises a bandpass filter.

5 . The test and measurement instrument as claimed in claim 4 , wherein the bandpass filter has a bandwidth greater than a target bandwidth of the WSA and narrower than the sample rate.

6 . The test and measurement instrument as claimed in claim 1 , wherein the one or more channels comprises multiple channels.

7 . The test and measurement instrument as claimed in claim 6 , wherein the at least one ADC comprises two ADCs, each ADC having two or more pipes.

8 . The test and measurement instrument as claimed in claim 1 , wherein the code that causes the one or more processors to use the spectrum of the digital samples comprises combining the spectrums of the two pipes and a starting frequency to reconstruct the spectrum.

9 . The test and measurement instrument as claimed in claim 8 , wherein the code that causes the one or more processors to combine the spectrum of the two pipes comprises code to cause the one or more processors to:
derive first and second constants using frequencies derived from low frequency components of spectrums of the two pipes; and use the two constants and the low frequency components of the spectrums of the two pipes.

10 . The test and measurement instrument as claimed in claim 8 , wherein the starting frequency is between a multiple of the sample rate and a multiple of the sample rate minus the Nyquist frequency.

11 . The test and measurement instrument as claimed in claim 8 , wherein the starting frequency is between the sample rate and a multiple of the sample rate plus the Nyquist frequency.

12 . The test and measurement instrument as claimed in claim 1 , wherein the one or more processors are further configured to calibrate the pipes in each ADC.

13 . The test and measurement instrument as claimed in claim 11 , wherein the code that causes the one or more processors to calibrate the pipes in each ADC comprises code that causes the one or more processors to characterize one or more of each pipe in each ADC, the filter, and the sampler associated with each pipe to acquire a frequency spectrum for each pipe.

14 . A method of operating a test and measurement device, comprising:
receiving a signal under test through a channel of the test and measurement device, the channel comprising an input port, a filter, and a sampler; producing digital samples of the signal under test at a sample rate using an analog-to-digital converter (ADC), the ADC having two pipes connected to the sampler of the channel; acquiring a spectrum of the digital samples for the two pipes in the ADC; and using the spectrums of the digital samples for the two pipes in the ADC to reconstruct the spectrum of the signal under test.

15 . The method as claimed in claim 14 , wherein using the spectrums of the digital samples comprises combining the spectrums of the two pipes and a starting frequency.

16 . The method as claimed in claim 15 , wherein using the spectrums of the digital samples comprises:
deriving first and second constants using frequencies derived from low frequency components of spectrums of the two pipes; and using the two constants and the low frequency components of the spectrums of the two pipes.

17 . A method of calibrating a test and measurement instrument operating as a wideband signal analyzer, comprising:
characterizing pipes of an analog-to-digital converters (ADC) to produce frequency responses of each pipe; acquiring a spectrum of digital samples for each pipe in the at least one ADC; and adjusting the spectrums of the digital samples based upon the frequency responses of each pipe; and using the adjusted spectrums of the digital samples for all pipes of each ADC to reconstruct the spectrum of signals under test.

18 . The method as claimed in claim 17 , wherein characterizing the pipes comprises:
applying a signal to a bandpass (BP) filter; using a sampler to sample the signal from the BP filter; feeding the samples from the BP filter into each pipe of the ADC; using the test and measurement instrument to acquire samples from each pipe; and obtaining the spectrum of the samples to determine the frequency response.

19 . The method as claimed in claim 17 , wherein characterizing the pipes of the ADC includes characterizing one or more of the BP filter, the sampler, and the ADC together or separately.

20 . The method as claimed in claim 18 , further comprising leveling the signal using a power meter.

Assignees

• Tektronix Inc

Inventors

• Tan Kan

Classifications

• H03M1/1085

  using domain transforms, e.g. Fast Fourier Transform · CPC title

• H03M1/1014

  at one point of the transfer characteristic, i.e. by adjusting a single reference value, e.g. bias or gain error (gain setting for range control H03M1/18) · CPC title

• H03M1/108 Primary

  Converters having special provisions for facilitating access for testing purposes · CPC title