An Integrated Magnetic Sensor with Two Continuous-Time /spl Delta//spl Sigma/-Converters and Stress Compensation Capability

Abstract

Accurate magnetic sensors with digital signal processing and means for individual adjustment are required for many automotive and industrial applications. Previous magnetic sensors have used separate choppers, preamps, anti-aliasing filters and switched capacitor converters, but the compact magnetic sensor presented here combines the spinning-current Hall probe and a chopped 3 rd -order continuous-time ∆Σ-converter (CT-∆Σ-ADC) with multibit feedback to optimize noise and EMI performance at minimum chip area and power (Fig 16.6.1). The improved architecture of the CT-ADC includes an additional digital tracking loop and range switching in the feedback DAC (Fig. 16.6.2) to increase the robustness and the DR to 90dB in a bandwidth of 4kHz.

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

“…Both types can be made with the same doping type and concentration to equalize their temperature coefficients and technology variation. Digital stress compensation as presented in [3] will support the new analog stress pre-compensation presented in this paper. This is only a firmware update.…”

“…Digital compensation Figure 1. Coreless differential magnetic current sensor with 4kV isolation based on resistors with different diffusion type is shown in [3]. It needs only low additional current consumption (~50µA).…”

“…This enables absolute measurements of currents smaller than 0.1% of maximum current (50A) in a temperature range -40°C to 150°C. Contrarily analog chopper offset ripple compensation methods were used in [3,5]. They suffer from large capacitors required for analog integration in the ripple feedback path.…”

Compensation of the Piezo-Hall Effect in Integrated Hall Sensors on (100)-Si

“…With the advent of analogue CMOS technologies, it became possible to implement the long known spinning current principle [1], which reduces the Hall probe offset by two to three orders in magnitude [2], [3]. Another major step forward was the integration of memories into these analogue technologies, which are programmable after the die has been assembled in its package.…”

“…Although the package significantly alters the magnetic sensitivity and the temperature coefficient of the magnetic sensitivity [4], one may compensate for this by individual calibration after the package process. Nowadays, a 12 bit wide third-order temperature compensation with coefficients stored in an on-chip EEPROM and the computation carried out in the on-chip digital signal processor is state-of-the-art [3], [5].…”