Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Plural inputs
Patent
1987-05-15
1988-11-22
Eisenzopf, Reinhard J.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Plural inputs
324130, 330 9, 364483, G01R 1906, G01R 1900
Patent
active
047868635
ABSTRACT:
A switched-capacitor integrator is employed in an electronic watthour measurement device for integrating the average component of a product signal formed by pulse-width modulating an analog signal proportional to one of a load current and voltage at a pulse duty ratio proportional to the other of the load current and voltage. A hysteresis comparator forces the direction of integration to alternate between positive and negative limits for balancing out offset voltages in the integrator and comparator. A triangular-wave generator employed as part of the pulse-width-modulation technique is also implemented using a switched-capacitor integrator. The switched-capacitor integrators permit fabrication of the circuit with the required accuracy without needing external, discrete time-constant-determining resistances and capacitances. Measurement accuracy is determined by the ratio of capacitances of two on-chip capacitors, the accuracy to a clock signal and two reference voltages. These parameters are closely controllable on a single MOS or CMOS chip using normal process control whereby the entire electronic watthour measurement device may be realized on a single chip without requiring off-chip components.
REFERENCES:
patent: 4315212 (1982-02-01), Gamoh
patent: 4535287 (1985-08-01), Milkovic
patent: 4616185 (1986-10-01), van Roermund
patent: 4682102 (1987-07-01), Milkovic
"MOS Sampled Data Recursive Filters Using Switched Capacities Integrators", by Hosticka et al., IEEE Journal of Solid St. Ckts., vol. SC-12, #6, 12/77, pp. 250-258.
Effect of Switch and Routing Related Parasitic Capacitances, M. S. Ghausi, et al., Modern Filter Design, pp. 456-461, Prentice Hall, 1981.
Burns W.
Eisenzopf Reinhard J.
General Electric Co.
Morrison Thomas R.
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