Output details

Fluxgate magnetic sensor with overload detection

This patent originated from research in CUED on micro-fabricated magnetic sensors; in particular for high frequency, non-contact current probes. The research encompassed the development of materials, structures and processes for the micro-fabrication of fluxgate magnetic sensors, together with matching RF interface circuitry to optimise the sensor dynamic range, bandwidth and SNR.

The fluxgate principle offers unrivalled sensitivity for a miniature device but does suffer from fold-back at high fields. This patent covers a method and circuitry to mitigate the effects of overload fold-back, by detecting the onset of saturation and latching the output accordingly; essential for its practical application in a general purpose instrument. Chris Wilding, Technical Director of Aim-TTi states “ This collaborative research project with Cambridge University has resulted in the successful development of a unique product in the test & measurement industry, expanding the product line for Aim-TTi into a new area. The state-of-the-art sensor research conducted in CUED enabled us to concentrate on the production engineering and marketing of the new product.”

The I-Prober 520 was one of the EDN Network ‘Hot 100 products of 2011’: http://www.edn.com/electronics-products/other/4368659/EDN-Hot-100-products-of-2011-Communications-and-test-instruments Review by Power Systems Design (PSD) “… The I-prober 520 is the only product in the world capable of observing and measuring currents in PCB tracks ... and ground planes…”http://www.powersystemsdesign.com/current-measurement-on-the-pcb?a=1&c=1205

This technology is employed in a new non-contact current probe, with the sensors manufactured by University start-up, Camjet, and the complete product by Thurlby Thandar Instruments (Chris Wilding, Technical Director, TeleNo_in_audit_file). The implementation of overload detection, novel to fluxgate sensors, is essential to practical use in a general purpose electrical instrument, http://www.electronicsweekly.com/Articles/01/09/2011/51780/aim-tti-works-with-cambridge-university-on-micro-fluxgate-current-probe.htm. This unique product, the I-Prober 520, is distributed worldwide, with annual sales in the thousands and a turnover to date of GBP1M and is the only commercially produced micro-fluxgate sensor available today.