发明名称 |
Digitizing ohmmeter system |
摘要 |
A digitizing ohmmeter system for providing a digital resistance measurement includes a current source for providing an excitation current to an impedance-varying input sensor and an ADC circuit including a charge-balancing modulator and a digital post processing circuit. The system utilizes synchronous AC excitation of the input sensor and an AC coupled analog-to-digital converter input. The digitizing ohmmeter system also implements correlated double sampling for noise cancellation to provide low noise and highly accurate analog-to-digital conversions. The ADC circuit includes a reference signal generator generating a resistance reference signal by time-sharing the excitation current with the input sensor. The digitizing ohmmeter system thereby realizes fully ratiometric operation such that neither a precise current source nor a precise voltage source is required for accurate resistance measurements.
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申请公布号 |
US6903558(B1) |
申请公布日期 |
2005.06.07 |
申请号 |
US20030423355 |
申请日期 |
2003.04.25 |
申请人 |
NATIONAL SEMICONDUCTOR CORPORATION |
发明人 |
BLOM ERIC D.;HOLLOWAY PETER R.;WAN JUN;URIE STUART H. |
分类号 |
G01R27/02;(IPC1-7):G01R1/38 |
主分类号 |
G01R27/02 |
代理机构 |
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代理人 |
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地址 |
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