Patent ID: 9395253
Filing Date: 2016-07-19
CPC Classification: G01K

Claim Text:
1. A method for cancelling series-resistance errors in a temperature sensor, the method comprising: measuring a first voltage delta across a semiconductor device having a known voltage drop characteristic that is proportional to absolute temperature (PTAT) by using a delta sigma analog to digital converter (ADC) with double sampling to measure the first voltage delta across the semiconductor device produced by a ratio of current densities using a first bias current having a value of N×I(bias) and a second bias current having a value of I(bias), by repeatedly sampling the voltage drop produced by N×I(bias) during a sample phase of the ADC and sampling the voltage drop produced by I(bias) during an integration phase of the ADC; measuring a second voltage delta across the semiconductor device, produced by a third bias current having a value of M×I(bias) and by a fourth bias current having a value of M×N×I(bias), by repeatedly sampling in reverse order the voltage drop produced by M×I(bias) during a sample phase of the ADC and sampling the voltage drop produced by M×N×I(bias) during an integration phase of the ADC; determining a corrected voltage delta by sampling the first voltage delta M times more often than sampling the second voltage delta, such that the reverse order of the currents used to establish the second voltage delta causes the second voltage delta to be subtracted from M times the first voltage delta resulting in a net voltage delta that is proportional to absolute temperature; and converting the corrected PTAT voltage delta to a temperature value by using a known temperature-dependent voltage drop characteristic of the semiconductor device.