Technology Overview

Resonant Inductive Position Sensing technology is used to precisely measure the position of a target without mechanical or electrical contact. The target's position is measured using a sensor built with conventional Printed Circuit Board (PCB) technology.  The target houses an electrical resonator comprising an inductor and capacitor. An electronic processing system interacts with the sensor to power the resonator and to detect the signals that it returns. The detected amplitudes of these signals are processed to calculate position.
resonant inductive position sensor system block diagram
CambridgeIC’s single-chip processing solutions are called Central Tracking Units (CTUs). These enable customers to embed non-contact position encoders into their products with the minimum of effort, and to deploy those solutions in high volume at low cost.

Sensor Designs

CambridgeIC has developed a range of standard sensors, including rotary and linear in different types and sizes. They are built using conventional printed circuit board (PCB) technology. CambridgeIC supplies Sensor Blueprints to allow a customer's own PCB supplier to build sensors.  This also allows a customer to design PCBs that combine one or more sensors with other electronic circuitry. Sensors are also available as finished PCBs assembled with modular connectors for development and low-volume production.

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Position Calculation

Position Calculation is performed automatically inside CambridgeIC’s CTU chips. Resonant inductive position sensors use ratiometric calculations for immunity to resonator Q-factor, supply voltage and component variations.

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CambridgeIC’s CTU chips generate a drive waveform that is used to inductively power the resonator inside a target, and detection circuitry to measure the levels of return signals from which coupling factors are determined.

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Technology Comparison

The following tables illustrate how CambridgeIC's resonant inductive sensing compares with traditional technologies. The attributes are selected for their importance in typical high-volume product applications requiring a precise, built-in sensor.

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Arc Position Sensor Comparison

CambridgeIC’s Arc Position Sensors are for embedded, non-contact measurement or angle inside machines. The angle to be measured is typically limited by the application, for example to 90°. This means an arc shaped sensor may be used, instead of a circular rotary sensor typical for full 360° angle measurement. The principle of operation is like a CambridgeIC linear sensor, except curved in an arc around the rotation axis.

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