Abstract A mean power detector circuit utilizes a differential amplifier on an integrated circuit chip to measure the true mean power of any waveform. A suitable resistor is thermally coupled to one transistor of the amplifier and is substantially isolated from the other transistor. When the resistor is connected to the signal to be measured, the thermal dissipation in the resistor affects the volt-ampere characteristics of the transistor to which it is coupled. Changes resulting from variations in ambient conditions or transistor characteristics are rejected by the differential arrangement. Thus the output of the amplifier is a measure of the mean power of the input signal and therefore is a measure of either the mean square voltage or the mean square current of the signal source.
Inventors
👤 Tadikonda N Rao
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-28 17:05
CPC Classifications
G; G01; G01R; G01R21/00; G01R21/02
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
147 words
Apparatus for measuring the mean power of an electrical signal comprising, in combination, first and second transistor differentially connected, said transistors comprising a single integrated circuit chip and having matched characteristics, a resistor for converting said power of said electrical signal to thermal power, said resistor being thermally coupled to said first transistor and thermally isolated from said second transistor, a pair of output terminals connected to the collector electrodes of said first and second transistors, and means for equally biasing said first and second transistors to cause equal conduction of both transistors when no thermal power is being coupled to the apparatus, whereby the difference in potential between said output terminals caused by increased conduction of the first transistor due to its increased temperature as a result of heating by thermal power generated in the resistor is a measure of said mean power of said signal.
Claim 2
Dependent Claim
147 words
Apparatus for measuring the mean power of an electrical signal comprising, in combination, first and second transistor differentially connected, said transistors comprising a single integrated circuit chip and having matched characteristics, a resistor for converting said power of said electrical signal to thermal power, said resistor being thermally coupled to said first transistor and thermally isolated from said second transistor, a pair of output terminals connected to the collector electrodes of said first and second transistors, and means for equally biasing said first and second transistors to cause equal conduction of both transistors when no thermal power is being coupled to the apparatus, whereby the difference in potential between said output terminals caused by increased conduction of the first transistor due to its increased temperature as a result of heating by thermal power generated in the resistor is a measure of said mean power of said signal.