High resolution temperature measurement

An apparatus for measuring high resolution temperature, comprising:

• a clock providing a plurality of clock pulses, each of the plurality of clock pulses representing a coarse time increment;
• a counter having a dock input coupled to the dock for receiving the plurality of clock pulses, and a stop input for stopping the counter from counting a count value, wherein the count value represents a number of clock pulses counted by the counter;
• a first output driver having an output coupled to a first node;
• a second output driver having an output coupled to a second node;
• a resistive temperature sensor coupled between the first and second nodes;
• a charging capacitor coupled to the second node and a voltage common node;
• a voltage reference having a reference voltage output;
• a voltage comparator having a positive input coupled to the second node and a negative input coupled to the output of the voltage reference, wherein the voltage comparator compares a voltage on the charging capacitor coupled to the second node to the reference voltage from the voltage reference output;
• a charge time measurement unit (CTMU) for providing a timed charge to a CTMU timing capacitor;
• wherein when outputs of the first and second output drivers go from first logic levels to second logic levels the counter starts counting the number of clock pulses until after a voltage on the charging capacitor coupled to the second node is equal to the reference voltage, the CTMU starts the timed charge to the CTMU timing capacitor when the voltage on the charging capacitor is equal to the reference voltage and stops the timed charge at a next clock pulse from the clock;
• a digital processor for reading the count value from the counter, a voltage on the CTMU timing capacitor, calculating a coarse time from the count value, and a fine time from the voltage on the CTMU timing capacitor;
• and
• the digital processor further corrects the coarse time using the fine time and thereafter converts a resulting corrected time to a temperature value.