Christian Reidl

A miniature digital current sensor with differential Hall probes using enhanced chopping techniques and mechanical stress compensation

A 10kHz bandwidth 50Amax current sensor using a Hall effect gradiometer without magnetic core provides 80kHz update rate with a digital interface. Very low un-calibrated offset of 30mA (1σ) and after calibration typical 10mA over temperature is accomplished by a chopped multi-bit feedback continuous-time 3rd order ΔΣ-ADC. This also realizes low noise of 13mArms in 1kHz signal bandwidth. The ADC uses enhanced chopping techniques and additional digital feedback loops to avoid chopper ripple. New analog and digital stress-compensation circuits with lateral and vertical n-doped resistors achieve lifetime gain drifts below 1% and temperature compensation. Auto-zeroing ping-pong comparators offer a fast over-current detection of 1...2μs on a dedicated output pin. The monolithic integrated sensor chip and the 4kV galvanic isolated current rail fit into a very small 7×7×1mm3 package.

Integrated Gigant Magnetic Resistance based Angle Sensor

An integrated GMR (giant-magnetic-resistance) sensor is presented for 360deg angular measurements of rotating magnetic fields in automotive applications. The spin-valve GMR-layers are directly applied to a standard semiconductor 0.22 mum CMOS process by vertical integration of the sensor-bridges atop of active circuitry. The entire integrated angle-sensor comprises 2 orthogonal magnetized GMR-bridges for sine and cosine signal measurements, and the subsequent signal conditioning circuitry. The entire angular sensor is designed to work in harsh automotive environment in a temperature range of -40degC to 150degC. The strength for best precision covers a wide range from 20 to 50 mT. The resulting angular information itself can be obtained by SPI-readout and calculating the arc-trigonometric function of the bridge signals with a resolution of >13 bit in an auxiliary microcontroller. After individual calibration to compensate for production spread an accuracy of typical 0.5deg is achieved.

Runtime Monitoring with Recovery of the SENT Communication Protocol

We show how the requirements of the SENT communication protocol between a magnetic sensor and an electronic control unit (ECU) can be monitored in real time, with a monitor capable of processing 70 million samples per second. We elaborate on a complete flow from formalizing electrical and timing requirements using Signal Temporal Logic (STL) and Timed Regular Expressions (TRE), to implementing runtime monitors in FPGA hardware and evaluating the results in the lab. For a class of asynchronous serial protocols, we define a procedure to obtain monitors that are capable to recover after violations. We elaborate on two different approaches to monitor the requirements of interest: (i) temporal testers with SystemC, STL and High-Level Synthesis; (ii) automata-based approach with TRE in HDL. We also present how the results of the monitoring can be used for error logging to provide users with extensive debugging information. Our approach allows to monitor requirements-specification conformance in real time for long-term tests.