Measurement System with large dynamic range
First Claim
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1. A measurement system that receives an input signal and provides an output signal indicating the magnitude of the input signal, with the amplifier circuit having a large dynamic range, said measurement system comprising:
- a high-gain amplifier circuit, including an operational amplifier having inverting and non-inverting input terminals and an output terminal, with a high-gain feedback resistor coupling the output terminal to the inverting input terminal;
a low-gain amplifier circuit, including an operational amplifier having inverting and non-inverting input terminals and an output terminal, with a low-gain feedback resistor coupling the output terminal to the inverting input terminal;
a detector, having first and second terminals, for generating a measurement signal having a magnitude indicating the magnitude of a quantity to be measured, with the fist terminal of said detector coupled to the inverting input of said high-gain amplifier and the second terminal coupled to the inverting input of said low-gain amplifier; and
a shunt feedback circuit, coupled to the inverting and output terminals of said high-gain amplifier circuit and coupled to receive a reference voltage signal of a predetermined magnitude, said shunt feedback circuit for shunting current from the high-gain feedback resistor when an output voltage magnitude at the output terminal of the high-gain amplifier circuit is greater than said predetermined magnitude to reduce the gain of the high-gain amplifier circuit and prevent is from saturating for large input signals.
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Abstract
A measurement circuit having high dynamic range includes high-gain and low-gain amplifiers connected in parallel. A shunt feedback circuit is activated to prevent the high-gain amplifier from saturating when the magnitude of an input signal exceeds its dynamic range. The output of the high-gain amplifier is utilized to measure small input signals and the output of the low-gain amplifier is utilized to measure large input signals.
18 Citations
4 Claims
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1. A measurement system that receives an input signal and provides an output signal indicating the magnitude of the input signal, with the amplifier circuit having a large dynamic range, said measurement system comprising:
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a high-gain amplifier circuit, including an operational amplifier having inverting and non-inverting input terminals and an output terminal, with a high-gain feedback resistor coupling the output terminal to the inverting input terminal; a low-gain amplifier circuit, including an operational amplifier having inverting and non-inverting input terminals and an output terminal, with a low-gain feedback resistor coupling the output terminal to the inverting input terminal; a detector, having first and second terminals, for generating a measurement signal having a magnitude indicating the magnitude of a quantity to be measured, with the fist terminal of said detector coupled to the inverting input of said high-gain amplifier and the second terminal coupled to the inverting input of said low-gain amplifier; and a shunt feedback circuit, coupled to the inverting and output terminals of said high-gain amplifier circuit and coupled to receive a reference voltage signal of a predetermined magnitude, said shunt feedback circuit for shunting current from the high-gain feedback resistor when an output voltage magnitude at the output terminal of the high-gain amplifier circuit is greater than said predetermined magnitude to reduce the gain of the high-gain amplifier circuit and prevent is from saturating for large input signals. - View Dependent Claims (2, 3)
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4. A measurement system comprising:
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a detector for generating a measurement signal having a signal amplitude; a plurality of amplifiers, each having a dynamic range and having parallel inputs coupled to receive said measurement signal; a shunt feedback circuit coupled to at least one amplifier to shunt current from said at least one amplifier when the signal amplitude exceeds the dynamic range of said at least one amplifier to prevents said at least one amplifier from saturating to assure an other amplifier in said plurality remains functional when said signal amplitude exceeds said dynamic range of said at least one amplifier.
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Specification