Source: http://www.google.com/patents/US4831325?dq=6,308,317
Timestamp: 2017-09-23 08:26:42
Document Index: 760383296

Matched Legal Cases: ['art 1', 'art 2', 'art 1', 'art 2', 'art 2', 'art 2']

Patent US4831325 - Capacitance measuring circuit - Google Patents
A variable capacitor, which may be a humidity sensitive capacitor, and a fixed reference capacitor are connected at a node. The node is clamped at a reference potential during a first phase of a two phase measuring cycle as the variable capacitor is charged to a fixed voltage and the fixed capacitor...http://www.google.com/patents/US4831325?utm_source=gb-gplus-sharePatent US4831325 - Capacitance measuring circuit
Publication number US4831325 A
Application number US 07/032,664
Also published as CA1283168C, DE3886244D1, DE3886244T2, EP0285070A1, EP0285070B1
Publication number 032664, 07032664, US 4831325 A, US 4831325A, US-A-4831325, US4831325 A, US4831325A
Inventors Charles W. Watson, Jr.
Patent Citations (13), Non-Patent Citations (12), Referenced by (85), Classifications (11), Legal Events (4)
US 4831325 A
______________________________________for φ1       for φ2______________________________________Qx1 = Cx (-Vt1)                 Qx2 = Cx (Vs - Vt2)Qo1 = Co (Vs - Vt1)                 Qo2 = Co (-Vt2)Qr1 = Cr (Vo - Vt1)                 Qr2 = Cr (-Vt2)Qy1 = Cy (-Vt1)                 Qy2 = Cy (-Vt2).If ΔQ = Q1 - Q2 and ΔVt = Vt2 - Vt1,then ΔQx = Cx (-Vs + ΔVt),ΔQo = Co (Vs + ΔVt),ΔQr = Cr (Vo + ΔVt),and ΔQy =  Cy (ΔVt).______________________________________
ΔQx +ΔQo +ΔQr +ΔQy =0;
ΣC=Cx +Co +Cr +Cy,
Cx (-Vs +ΔVt)+Co (Vs +ΔVt)+Cr (Vo +ΔVt)+Cy (ΔVt)=0,
Vs (Co -Cx)+Cr Vo +ΣCΔVt =0.
G=(α-1)Cx (0) (Vs)/Cr
Vos =Cx (0)-Co (Vs)/Cr
G=(α-1)Vos +((α-1)Co)/Cr Vs.
US3221247 * Feb 8, 1963 Nov 30, 1965 Simmonds Precision Products Solid state capacity servo measuring system utilizing inductive feedback
GB2020434A * Title not available
JPS61235745A * Title not available
1 "Design of Nonlinear Analog Switched-Capacitor Circuit Building Blocks" by Hosticka et al., IEEE Transactions and Systems; Apr. 1984, pp. 354-367.
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6 * Design of Nonlinear Analog Switched Capacitor Circuit Building Blocks by Hosticka et al., IEEE Transactions and Systems; Apr. 1984, pp. 354 367.
7 * Iwai et al.; Capacitance Measurement Circuits in VSLI Structures, IEEE Trans. on Electron Devices, vol. ED 29, No. 10, Oct. 1982, pp. 1622 1626.
8 Iwai et al.; Capacitance Measurement Circuits in VSLI Structures, IEEE Trans. on Electron Devices, vol. ED-29, No. 10, Oct. 1982, pp. 1622-1626.
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10 Matsumoto et al., A Switched-Capacitor Digital Capacitance Meter; IEEE Trans on Inst., vol. IM-35, No. 4, Part 2, Dec. 1986, pp. 555-559.
11 * Precision Measurement Technique of Integrated MOS Capacitor Mismatching Using a Simple On Chip Circuit by Masakazu Furukawa, Hidetoshi Hatano, and Koji Hanihara, IEEE Trans. on Elect. Dev., vol. ED 33, No. 7, Jul. 1986.
12 Precision Measurement Technique of Integrated MOS Capacitor Mismatching Using a Simple On-Chip Circuit by Masakazu Furukawa, Hidetoshi Hatano, and Koji Hanihara, IEEE Trans. on Elect. Dev., vol. ED-33, No. 7, Jul. 1986.
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U.S. Classification 324/678, 324/601, 73/724, 324/679, 324/665
European Classification G01R27/26B, G01N27/22C2