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High-bandwidth isolated current sensing for SiC and GaN power electronics

At the University of Bristol, we have been using Infinity Sensors to measure transient currents since 2016.

A prototype Infinity Sensor is shown in the photo below. It is a surface-mount device, around 3×8 mm in outline with a cable connector on top, that is placed in a circuit to measure fast-changing currents. We especially like that the bandwidth is high enough for GaN power converters, and that the insertion impedance is almost negligible.


We are currently offering samples of our Infinity Sensors V2. The V2 is 3.5×8 mm, and has a bandwidth that exceeds 1 GHz. The graph below was measured using an Infinity Sensor V2 on the source of a low-side GaN device in a bridge leg. The waveform contains features, such as the turn-on surge and subsequent ringing, that require a bandwidth of at least 500 MHz to resolve. Also, in order for a circuit to switch at the speed shown, the insertion impedance of any current sensing needs to be well below 1 nH. The insertion impedance of the Infinity Sensor V2 is below 0.3 nH. This includes the additional parasitic inductance of adding the sensor to the board layout. 


We also provide the code that we use to counter offset and perform the required mathematical integration.

We have sampled hundreds of these sensors to over 50 organisations and have significantly improved the reliability and user-friendliness of these sensors. We are now offering samples of the latest version, Infinity Sensor V2, via the Online Shop of the University of Bristol. Go to Services to find out more.

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