An integrated signal conditioner for high-frequency inductive position sensors

作者：Rahal Mohamad^*; Demosthenous Andreas

来源：Measurement Science and Technology, 2010, 21(1): 015203.

DOI：10.1088/0957-0233/21/1/015203

• analogue
• CMOS integrated circuits
• capacitive coupling
• differential mixer
• inductive position sensor
• signal conditioner
• synchronous detection

This paper describes the design, implementation and evaluation of a signal conditioner application-specific integrated circuit (ASIC) for high-frequency inductive non-contact position sensors. These sensors employ a radio frequency technology based on an antenna planar arrangement and a resonant target, have a high inherent resolution (0.1% of antenna length) and can measure target position over a wide distance range (<0.1 mm to >10 m). However, due to the relatively high-frequency excitation (1 MHz typically) and to the specific layouts of these sensors, there is unwanted capacitive coupling between the transmitter and receiver coils; this type of distortion reduces linearity and resolution. The ASIC, which is the first generation of its kind for this type of sensor, employs a differential mixer topology which suppresses the capacitive coupling offsets. The system architecture and circuit details are presented. The ASIC was fabricated in a 0.6 mu m high-voltage CMOS technology occupying an area of 8 mm(2). It dissipates about 30 mA from a 24 V power supply. The ASIC was tested with a high-frequency inductive position sensor (with an antenna length of 10.8 cm). The measured input-referred offset due to transmitter crosstalk is on average about 22 mu V over a wide phase difference variation (-99 degrees to +117 degrees) between the transmitter and demodulating signals.

• 出版日期2010-1