Digital-domain-integrated, voltage-to-frequency temperature sensor

A digital-domain-based thermal sensor comprising:

• a filter to filter a digital chip supply voltage into a filtered digital supply voltage;
• a bandgap reference circuit configured to generate, from the filtered digital supply voltage, a reference voltage and a proportional-to-absolute temperature (PTAT) voltage;
• and
• a closed-loop readout circuit coupled to the bandgap reference circuit and comprising:
• sets of switched capacitors that operate as a voltage divider, wherein capacitors of the sets of switched capacitors are selectively charged by the PTAT voltage and generate a feedback voltage;
• a voltage-controlled oscillator (VCO) driven by a difference between the feedback voltage and the reference voltage and to generate a VCO clock;
• and
• a clock generator to generate a feedback clock based on the VCO clock, wherein first switches of the sets of switched capacitors are controlled by the feedback clock;
• and
• a digital counter coupled to the clock generator, the digital counter to generate a digital output based on a number of cycles of a reference clock that fit into a cycle of the feedback clock.

A network communication switch comprising:

• an integrated circuit chip comprising a digital chip supply voltage and configured to process network packets over one or more ports, wherein the integrated circuit chip comprises:
• a filter to filter the digital chip supply voltage into a filtered digital supply voltage;
• a bandgap reference circuit configured to generate, from the filtered digital supply voltage, a reference voltage and a proportional-to-absolute temperature (PTAT) voltage;
• and
• a closed-loop readout circuit coupled to the bandgap reference circuit and comprising:
• sets of switched capacitors that operate as a voltage divider, wherein one or more capacitors of the sets of switched capacitors are selectively charged by the PTAT voltage via first switches of the sets of switched capacitors to generate a feedback voltage, and wherein the one or more capacitors being selectively charged operate as a frequency-to-current converter;
• a voltage-controlled oscillator (VCO) driven by a difference between the feedback voltage and the reference voltage and to generate a VCO clock;
• and
• a clock generator to generate a feedback clock based on the VCO clock, wherein switches of a first bank of switched capacitors of the sets of switched capacitors are controlled by the feedback clock.