Circuits and methods for current measurements referred to a precision impedance
First Claim
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1. A circuit that determines a current supplied by an integrated circuit comprising:
- a sensing impedance disposed on the integrated circuit;
a modulation impedance;
a first measurement device coupled to the modulation and sensing impedances and configured to measure a first voltage drop across each impedance;
a termination impedance;
a second measurement device coupled to the termination impedance and configured to measure a second voltage drop across the termination impedance; and
processing circuitry configured to receive the first and second voltage drops measured by the first and second measurement devices, respectively, and to calculate supplied current therefrom.
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Abstract
Circuitry and methods for obtaining accurate measurements of current supplied by an integrated circuit are provided. Current calculations are performed using information from a precision termination resistor and from the ratio relationship of two on-chip resistors. The invention provides a way to obtain accurate current measurements without the use of component trimming.
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Citations
15 Claims
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1. A circuit that determines a current supplied by an integrated circuit comprising:
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a sensing impedance disposed on the integrated circuit; a modulation impedance; a first measurement device coupled to the modulation and sensing impedances and configured to measure a first voltage drop across each impedance; a termination impedance; a second measurement device coupled to the termination impedance and configured to measure a second voltage drop across the termination impedance; and processing circuitry configured to receive the first and second voltage drops measured by the first and second measurement devices, respectively, and to calculate supplied current therefrom. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for determining a current supplied by an integrated circuit comprising:
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determining a voltage drop across a termination impedance with respect to a reference voltage; comparing a voltage drop across a first impedance on the integrated circuit with a voltage drop across a second impedance on the integrated circuit, wherein the first impedance is different from the second impedance; processing information obtained in the determining and comparing steps to obtain a value for the supplied current; determining an impedance value of the first impedance, an impedance value of the second impedance, the voltage provided by the voltage reference, and the impedance value of the termination impedance; and calculating a first value by dividing the value of the second impedance by the value of the first impedance, calculating a second value by dividing the value of the voltage drop across the termination impedance by the value of the reference voltage, calculating a third value by dividing the value of the reference voltage by the value of the termination impedance, calculating a fourth value by dividing the value of the voltage drop across the first impedance by the value of the reference voltage, calculating a fifth value by dividing the value of the voltage drop across the second impedance by the value of the reference voltage, and wherein the comparing further comprises calculating a sixth value by dividing the voltage drop across the first impedance by the voltage drop across the second impedance. - View Dependent Claims (11, 12, 13)
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14. Circuitry for determining a bias current provided by an integrated circuit comprising:
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an off-chip impedance, not disposed on the integrated circuit, having a known resistance; a source impedance disposed on the integrated circuit, wherein a first terminal of the source impedance is coupled to a first terminal of the off-chip impedance; a modulation impedance disposed on the integrated circuit, wherein a second terminal of the modulation impedance is coupled to a second terminal of the off-chip impedance; a first measurement device for measuring an off-chip voltage drop across the off-chip impedance with respect to a reference voltage; a second measurement device for measuring a source voltage drop across the source impedance with respect to a modulation voltage drop across the modulation impedance; and processing circuitry configured to determine the bias current based on the measurements of the first and second measurement devices.
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15. A method for controlling the amount of output power provided by an integrated circuit, the method comprising:
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measuring a first voltage drop across an off-chip impedance with respect to a reference voltage, wherein the off-chip impedance is not disposed on the integrated circuit, and the off-chip impedance has a known resistance; measuring a second voltage drop across a source impedance with respect to a third voltage drop across a modulation impedance, wherein the source and modulation impedances are disposed on the integrated circuit; determining a bias current based on the first, second and third voltage measurements; and adjusting the bias current based on the determined bias current to control the amount of output power provided by the integrated circuit.
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Specification