Ratiometric Temperature Sensor Circuit for RTD and NTC Linearity

The patent implements a universal temperature measurement circuit that can accurately measure both RTD and NTC temperature sensors using the same circuit topology. The circuit achieves this by dynamically adjusting the excitation current based on the sensor type and by using a microcontroller to process measurements from both sensor types through a unified measurement interface, eliminating the need for separate dedicated circuits for each sensor type.

The patent employs dynamic excitation current adjustment where the circuit automatically adapts the excitation current magnitude based on the connected sensor type (RTD or NTC) and the measured temperature range. This dynamic adaptation allows the single circuit to optimize measurement accuracy for different sensor characteristics without requiring separate fixed-topology circuits, thereby reducing overall system complexity while maintaining precision.

The patent incorporates feedback mechanisms where the microcontroller continuously monitors the voltage differential across the temperature sensor and the current sensor, then calculates and compensates for measurement errors. The system uses feedback to adjust the excitation current dynamically and to compensate for self-heating effects in RTDs and non-linear behavior in NTCs, maintaining high measurement precision without requiring complex analog compensation circuits.

The patent replaces complex analog linearization circuits with digital signal processing performed by a microcontroller. Instead of using elaborate analog circuitry to linearize NTC responses or compensate for RTD self-heating, the system uses digital algorithms to process the raw measurements, calculate temperature values, and apply corrections. This substitution of digital processing for analog circuit complexity achieves high precision while maintaining relatively simple hardware architecture.