Combination Current Generator for PTAT and CTAT Thermal Sensing
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Solution Overview
Problem
Conventional temperature sensors for integrated circuits require separate current generators for PTAT and CTAT signals, leading to increased circuit complexity and power consumption, which is not suitable for compact and low-power applications in modern portable and IoT devices.
Innovation Solution
A compact thermal sensor circuit utilizing a combination current generator that selectively generates both PTAT and CTAT currents, along with a current charge pump and convertor, to reduce area budget and power consumption, while maintaining temperature monitoring capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate PTAT and CTAT current generators are used, then temperature monitoring accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines the PTAT and CTAT current generation functions into a single current generator circuit. This unified generator uses a differential pair configuration where one transistor generates PTAT current and the other generates CTAT current, eliminating the need for separate generator circuits while maintaining both temperature-dependent current outputs for accurate temperature monitoring.
Solution Approach 2:
The single current generator is designed to perform multiple functions: it simultaneously generates both PTAT and CTAT currents that are essential for temperature sensing. This multi-functional design allows one circuit block to replace what would traditionally require two separate circuits, reducing overall system complexity while preserving measurement capabilities.
2Measurement precision
If separate PTAT and CTAT current generators are used, then temperature monitoring capabilities are maintained, but area occupied increases
Solution Approach 1:
By merging the PTAT and CTAT current generation into a single differential pair circuit, the patent significantly reduces the chip area required. The shared circuit elements and compact differential configuration minimize the spatial footprint while still providing both necessary current types for comprehensive temperature monitoring across different temperature ranges.
Solution Approach 2:
The circuit design nests the PTAT and CTAT generation functions within a single differential pair structure, where the two transistor branches are tightly integrated. This nested arrangement allows both current generation functions to coexist in a compact configuration, maximizing area efficiency on the chip.
3Adaptability or versatility
If separate PTAT and CTAT current generators are used, then full temperature sensing functionality is achieved, but power consumption increases
Solution Approach 1:
The patent merges the power consumption of two separate current generators into a single shared power supply network. The differential pair configuration allows both PTAT and CTAT currents to be generated from common biasing circuits and power rails, reducing redundant power consumption while maintaining full temperature sensing functionality across the operating range.
Data Source
AI summary
One embodiment of the instant disclosure provides a compact lower power thermal sensor that comprises a combination current generator configured to selectively generate a PTAT and a CTAT current; a convertor configured to generate digital output corresponding to the current mirrored by the current-reuse charge pump; and a current-reuse charge pump coupled between the combination current generator and the convertor, configured to mirror the current generated by the combination current generator and selectively establish a charging/discharging path to/from the convertor. The combination current generator selectively generates the PTAT and the CTAT current in accordance with an output state of the convertor, and the current-reuse charge pump selectively charges and discharges a capacitor of the convertor with the PTAT and the CTAT current in accordance with the output state of the convertor.