Self-calibrating analog to digital converter with predetermined transfer characteristics |
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| 申请号 | US3685048D | 申请日 | 1970-09-30 | 公开(公告)号 | US3685048A | 公开(公告)日 | 1972-08-15 |
| 申请人 | BENDIX CORP; | 发明人 | PINCUS RALPH M; | ||||
| 摘要 | An analog to digital converter having self-calibrating capability throughout its range at every desired point and including means for providing an analog to digital transfer function with variable offset and slope. | ||||||
| 权利要求 | 1. Apparatus including an A/D converter and self-calibrating means therefor, comprising: a first signal source for providing a reference signal in one sense; a second signal source for providing a reference signal in an opposite sense; a third signal source for providing an analog signal; an A/D converter including an integrator and a comparator connected to the integrator; means connected to the comparator for connecting the third signal source to the converter, the comparator being effective for comparing the analog signal and the integrator output and for providing a difference output; means for connecting the third signal source to ground; means connected to the integrator for selectively connecting one of the first and second signal sources to the A/D converter, with the converter providing a digital output corresponding to the analog signal when the one signal source of the first and second signal sources and the third signal source are connected thereto; a D/A converter connected to the A/D converter; first calibrating means connected to the D/A converter and responsive to the analog output therefrom for providing a first calibrating output when the third signal source is connected to ground and the one signal source of the first and second signal sources is connected to the A/D converter; and means connected to the first calibrating means and to the A/D converter for applying the first calibrating output to the comparator to correct the difference output for zero offset. 2. Apparatus as described by claim 1 including second calibrating means, comprising: means connected to the D/A converter and to the first signal source and responsive to the analog output and the first signal for providing a second calibrating output; means for disconnecting the first signal source from the integrator in the A/D converter; and means for connecting the means for providing a second calibrating output to the integrator in the A/D converter, said second calibrating output affecting said integrator for calibrating the output thereof in the one sense. 3. Apparatus as described by claim 1, including third calibrating means comprising: means connected to the D/A converter and to the second signal source and responsive to the analog output and the second signal for providing a third calibrating output; means for disconnecting the second signal source from the integrator in the A/D converter; and means for connecting the means for providing a third calibrating output to the integrator in the A/D converter, with said third calibrating output affecting said integrator for calibrating the output thereof in the opposite sense. 4. Apparatus as described by claim 1, wherein the first calibrating means includes: a sample and hold circuit connected to the D/A converter for sampling the output therefrom and having means for subsequently applying the sampled output to the comparator. 5. Apparatus as described by claim 2, wherein the means for providing a second calibrating output includes: a sample and hold circuit connected to the D/A converter for sampling the output therefrom; a comparator connected to the sample and hold circuit and to the first signal means for comparing the sampled output and the first signal; an integrator connected to the comparator for integrating the output therefrom; and a normally open switch connected intermediate the Comparator and the integrator, and closed for holding the output of the integrator at a desired level. 6. Apparatus as described by claim 3, wherein the means for providing a third calibrating output includes: a sample and hold circuit connected to the D/A converter for sampling the output therefrom; a comparator connected to the sample and hold means and to the second signal means for comparing the sampled output and the second signal; an integrator connected to the comparator for integrating the output therefrom; and a normally open switch connected intermediate the comparator and the integrator, and closed for holding the output of the integrator at a desired level. 7. Apparatus as described by claim 2, including: means for connecting the first signal source to the comparator; and said comparator being effective for comparing the integrator signal and the first signal for providing the difference output. 8. Apparatus as described by claim 3, including: means for connecting the second signal source to the comparator; and said comparator being effective for comparing the integrator signal and the second signal for providing the difference output. |
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