US4352160A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Statistical method of measuring the differential linearity of an analog/digital converter using a pseudo-random triangle wave stimulus
Assignee: United States Department of the Air Force
•
Filing: 1980-01-21
•
Granted: 1982-09-28
•
Expires: 2000-01-21
Abstract
Abstract The differential linearity of an analog-digital converter is measured by a test method that eliminates the need for precision calibrated test equipment. A triangle waveform with a pseudo random period is applied to the analog/digital converter input. The waveform has a uniform amplitude probability density function. Therefore, any analog/digital converter input voltage has an equal chance of being sampled by the analog/digital converter. The number of times each possible analog/digital converter output code word occurs is counted by a microprocessor. These numbers are a direct measure of differential linearity with an accuracy described by the theory of repeated random sampling.
Inventors
- 👤 John W. Frech
- 👤 Lonnie C. Au
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:00
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/10; H03M1/1071
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
228 words
The method of measuring the differential linearity of an analog/digital converter having an input and an output and a transfer characteristic represented by n coded steps, n being an integer, said method comprising the steps of generating a triangle waveform stimulus signal having a uniform amplitude probability density function and a pseudo random periodicity, the frequency of said triangle waveform stimulus signal having a relationship to the analog/digital sampling rate that permits equal sampling at all points along the analog/digital converter, said frequency being not less than 5 Hz nor more than 20 MHz, the repeat period of said pseudo random stimulus signal being substantially longer than the test period of said analog/digital converter, the amplitude of said triangle waveform stimulus signal being less than the analog/digital input signal voltage range, and the analog/digital converter D.C. being shifted to measure the linearity of a given portion of the analog/digital converter transfer characteristics, applying said signal to the input of said analog/digital converter, counting the number of times the output code word for each transfer characteristic step occurs, each step size being a function of the number of times its code word occurs, recording a list of all transfer characteristic step sizes, recording transfer characteristic step sizes that fall within discrete analog/digital converter step size windows, and recording D.C. locations for all values within any analog/digital step size window.
Claim 2
Independent Claim
228 words
The method of measuring the differential linearity of an analog/digital converter having an input and an output and a transfer characteristic represented by n coded steps, n being an integer, said method comprising the steps of generating a triangle waveform stimulus signal having a uniform amplitude probability density function and a pseudo random periodicity, the frequency of said triangle waveform stimulus signal having a relationship to the analog/digital sampling rate that permits equal sampling at all points along the analog/digital converter, said frequency being not less than 5 Hz nor more than 20 MHz, the repeat period of said pseudo random stimulus signal being substantially longer than the test period of said analog/digital converter, the amplitude of said triangle waveform stimulus signal being less than the analog/digital input signal voltage range, and the analog/digital converter D.C. being shifted to measure the linearity of a given portion of the analog/digital converter transfer characteristics, applying said signal to the input of said analog/digital converter, counting the number of times the output code word for each transfer characteristic step occurs, each step size being a function of the number of times its code word occurs, recording a list of all transfer characteristic step sizes, recording transfer characteristic step sizes that fall within discrete analog/digital converter step size windows, and recording D.C. locations for all values within any analog/digital step size window.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-09-27 | 1986-03-29 | 1986-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-09-27 | 1990-03-29 | 1990-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-09-27 | 1994-03-29 | 1994-09-28 | $7700.00 | Window Closed / Lapsed |