Linear integrated circuit temperature sensor apparatus with adjustable gain and offset
First Claim
1. A temperature sensor, comprising:
- a current source including a resistor RPTAT and generating a proportional to absolute temperature (PTAT) current IPTAT that is proportional to absolute temperature (T);
a current mirror coupled to the current source and having a first scaling factor N for scaling the PTAT current IPTAT by a factor of N to generate an N-scaled PTAT current;
a temperature sensor resistor RTS coupled to the first current mirror; and
an offset circuit coupled to the first current mirror and the temperature sensor resistor RTS, the offset circuit having a second scaling factor P and including an offset resistor ROFF and having a bandgap voltage VBG across the offset resistor ROFF, wherein the temperature sensor generates an output voltage VOUT across the temperature sensor resistor RTS, and wherein the offset circuit offsets the voltage across the temperature sensor resistor RTS by a voltage offset VOFF, wherein the voltage offset VOFF is the bandgap voltage VBG multiplied by the second scaling factor P and multiplied by the ratio of the temperature sensor resistor RTS to the offset resistor ROFF.
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Abstract
Embodiments of the invention include a temperature sensor apparatus, method and system for providing an output voltage response that is linear to the temperature of the integrated circuit to which the temperature sensor belongs and/or the integrated circuit die on which the temperature sensor resides. The output voltage of the temperature sensor has an adjustable gain component and an adjustable voltage offset component that both are adjustable independently based on circuit parameters. The temperature sensor includes a conventional bandgap circuit, which generates an internal PTAT (proportional to absolute temperature) current to produce a bandgap reference voltage, and a current mirror arrangement that provides a scaled current that is proportional to the bandgap circuit'"'"'s PTAT current. Conventionally, the scaled PTAT current is sourced through an output resistor to provide the output voltage of the temperature sensor. The inventive temperature sensor includes an offset circuit that diverts a portion of current from the scaled PTAT current before the current is sourced through the output resistor. Thus, the inventive temperature sensor subtracts an offset voltage from the output voltage, which offset voltage represents the desired voltage offset component. The offset circuit includes a bandgap circuit arrangement, a voltage to current converter arrangement, and a current mirror arrangement that are configured to provide a voltage offset that is adjustable based on independent circuit parameters such as resistor value ratios and transistor device scaling ratios. The gain component of the inventive temperature also is based on similar independent circuit parameters.
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Citations
20 Claims
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1. A temperature sensor, comprising:
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a current source including a resistor RPTAT and generating a proportional to absolute temperature (PTAT) current IPTAT that is proportional to absolute temperature (T);
a current mirror coupled to the current source and having a first scaling factor N for scaling the PTAT current IPTAT by a factor of N to generate an N-scaled PTAT current;
a temperature sensor resistor RTS coupled to the first current mirror; and
an offset circuit coupled to the first current mirror and the temperature sensor resistor RTS, the offset circuit having a second scaling factor P and including an offset resistor ROFF and having a bandgap voltage VBG across the offset resistor ROFF, wherein the temperature sensor generates an output voltage VOUT across the temperature sensor resistor RTS, and wherein the offset circuit offsets the voltage across the temperature sensor resistor RTS by a voltage offset VOFF, wherein the voltage offset VOFF is the bandgap voltage VBG multiplied by the second scaling factor P and multiplied by the ratio of the temperature sensor resistor RTS to the offset resistor ROFF. - View Dependent Claims (2, 3, 4, 5)
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6. A temperature sensor, comprising:
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a current source coupled between an upper supply voltage VCC and a lower supply voltage VSS, the current source including a resistor RPTAT and generating a PTAT current IPTAT that is proportional to absolute temperature T;
a current mirror coupled to the current source and the upper supply voltage VCC, the current mirror having a first scaling factor N for scaling up the PTAT current IPTAT by a factor of N to generate an N-scaled PTAT current;
a temperature sensor resistor RTS coupled to the current mirror and the lower supply voltage VSS; and
an offset circuit coupled to the current mirror and the temperature sensor resistor RTS, the offset circuit including an offset resistor ROFF and having a bandgap voltage VBG across the offset resistor ROFF, wherein the offset circuit diverts an offset current IOFF from the N-scaled PTAT current generated by the current mirror, wherein the remaining, non-diverted portion of the N-scaled PTAT current is sourced through the temperature sensor resistor RTS as a temperature sensor current IOUT, wherein the temperature sensor generates an output voltage VTS by the flow of the temperature sensor current IOUT through the temperature sensor resistor RTS, the output voltage VTS being a function of the absolute temperature T and a function of the bandgap voltage VBG, wherein the temperature sensor has a gain that is based on the ratio of the temperature sensor resistor RTS to the current source resistor RPTAT, and wherein the temperature sensor has a voltage offset that is based on the ratio of the temperature sensor resistor RTS to the offset resistor ROFF. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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15. An integrated circuit (IC), comprising:
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a die;
at least one integrated circuit chip coupled to the die; and
a integrated circuit temperature sensor coupled to the die for detecting the temperature of the at least one integrated circuit chip, the temperature sensor including a current source coupled between an upper supply voltage VCC and a lower supply voltage VSS, the current source including a resistor RPTAT and generating a PTAT current IPTAT that is proportional to absolute temperature T, a current mirror coupled to the current source and the upper supply voltage VCC, the current mirror having a first scaling factor N for scaling up the PTAT current IPTAT by a factor of N to generate an N-scaled PTAT current, a temperature sensor resistor RTS coupled to the current mirror and the lower supply voltage VSS, and an offset circuit coupled to the current mirror and the temperature sensor resistor RTS, the offset circuit having a first portion that generates a bandgap current IBG based on a bandgap voltage VBG across an offset resistor ROFF, and a second portion, coupled to the first portion, that scales up the bandgap current IBG to determine an offset current IOFF, wherein the offset circuit diverts the offset current IOFF from the N-scaled PTAT current generated by the current mirror, wherein the remaining, non-diverted portion of the N-scaled PTAT current is sourced through the temperature sensor resistor RTS as a temperature sensor current IOUT, wherein the temperature sensor generates an output voltage VTS by the flow of the temperature sensor current IOUT through the temperature sensor resistor RTS, the output voltage VTS being a function of the absolute temperature T and a function of the bandgap voltage VBG, wherein the temperature sensor has a gain that is based on the ratio of the temperature sensor resistor RTS to the current source resistor RPTAT, and wherein the temperature sensor has a voltage offset that is based on the ratio of the temperature sensor resistor RTS to the offset resistor ROFF. - View Dependent Claims (16, 17, 18)
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19. A method for detecting the temperature of one or more integrated circuits chips on an integrated circuit die, the method comprising the steps of:
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generating with a current source a PTAT current IPTAT that is proportional to absolute temperature T, the current source including a resistor RPTAT;
scaling with a current mirror having a scaling factor of N the PTAT current IPTAT to generate an N-scaled PTAT current;
diverting with an offset circuit an offset portion of current IOFF from the N-scaled PTAT current generated by the current mirror, the offset circuit having a bandgap voltage VBG across an offset resistor ROFF;
sourcing the remaining, non-diverted portion of the N-scaled PTAT current through a temperature sensor resistor RTS as a temperature sensor current IOUT, generating an output voltage VTS by the flow of the temperature sensor current ITS through the temperature sensor resistor RTS, the output voltage VTS being a function of the absolute temperature T and a function of the bandgap voltage VBG, wherein the temperature sensor has a gain that is based on the ratio of the temperature sensor resistor RTS to the current source resistor RPTAT, and wherein the temperature sensor has a voltage offset that is based on the ratio of the temperature sensor resistor RTS to the offset resistor ROFF. - View Dependent Claims (20)
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Specification