J. Kubik

Current sensor in PCB technology

A novel DC/AC current sensor works on the fluxgate principle. The core in the form of a 7/10-mm ring made of electrodeposited permalloy is sandwiched in the middle of a printed circuit board (PCB), whereas the sensor excitation winding is also integrated in the copper layers of the PCB. To lower the sensor power consumption, the excitation winding was tuned by a parallel capacitor. The peak-peak/rms ratio of 5.2 was achieved for the excitation frequency of 25 kHz. The open-loop sensor has 100-mV/A sensitivity; the characteristics have a linearity error of 10% and hysteresis below 0.1% in the 1-A range.

Low-Power Printed Circuit Board Fluxgate Sensor

A new printed circuit board flat fluxgate sensor with integrated coils and amorphous alloy core was developed and its excitation parameters optimized for low-power consumption. The power consumption achieved with 10 kHz, 300 mA p-p pulse excitation with duty cycle 12.5% was only 3.9 mW, which is three times lower than that for sinewave B excitation. The sensor sensitivity reached 94 V/T. The required excitation bridge supply voltage was only 0.47 V. The low-cost low-power sensor has a temperature offset stability of 120 nT in the -20 to +70 degC temperature range and 0.17%/degC open-loop sensitivity tempco due to the use of a new core embedding technique. The perming error due to 10 mT field shock was suppressed below 1.2 muT. The short-time offset stability was 38 nT within 3 h. Thus the developed sensor is more precise and less energy consuming than a periodically flipped anisotropic magnetoresistance (AMR) sensor. The achieved parameters are sufficient for compass with 0.1deg error

Excitation and temperature stability of PCB fluxgate sensor

Printed circuit board (PCB) integrated inductors have been adapted for operation as fluxgate sensors. A ring core is made from an electrodeposited permalloy thin film and is sandwiched between the layers of the PCB. The sensor excitation winding is also integrated into the PCB design. The pick-up coil is wound around the frame of the PCB core. Different types of current excitation waveforms with tuned and nontuned pick-up coils were used. The achieved sensitivities for 60 turns of tuned/nontuned pick-up coil, a sinusoidal waveform excitation current of Irms=300 mA, and an excitation frequency of 150 kHz were 13100/1800 V/T. The achieved sensitivity for pulse excitation (Ipeak-peak=900 mA, Irms=184 mA, duty 20%) was 2100 V/T. Noise power density for pulse excitation was 1.2 nTrms//spl radic/Hz@1 Hz, noise rms value from 10 mHz to 10 Hz was 3.3 nT. A perming error of 1 /spl mu/T was measured for a wide range of excitation currents.

Low-power PCB fluxgate sensor

New PCB (printed circuit board) technology flat fluxgate sensor with integrated coils and amorphous alloy core was developed and its excitation parameters were optimized for low-power consumption. The power consumption achieved with 10 kHz, 300 mA p-p pulse excitation with duty cycle 12.5% was only 3.9 mW, which is 3-times lower than that for sinewave flux density excitation. The sensor sensitivity reached 94 V/T. The required bridge supply voltage was only 0.47 V. The low-cost, low-power sensor has a temperature offset stability of 120 nT in the -20...+70 degC temperature range and 0.17%/degC open-loop sensitivity tempco due to the use of new core embedding technique. The perming error due to 10 mT field shock was suppressed below 1.2 muT

Excitation of PCB fluxgate sensor

Printed circuit board (PCB) integrated inductors have been adapted for operation as fluxgate sensors. The ring core is made from an electrodeposited permalloy thin film sandwiched between the layers of the PCB. The sensor excitation winding is also integrated into the PCB design. The pick-up coil is wound around the frame of the PCB core. Different types of current excitation waveform with tuned and non- tuned pick-up coils were used. Achieved sensitivities for 60 turns of tuned/non-tuned pick-up coil, a sinusoidal waveform excitation current of I/sub rms/=300mA, an excitation frequency of 150 kHz were 13100/1800 V/T. The achieved sensitivity for pulse excitation (I/sub peak-peak/=900mA, I/sub rms/=184mA, duty 20%,) was 2100 V/T. Noise power density for pulse excitation was 1.2 nTrms//spl radic/Hz@1Hz, noise rms value from 10 mHz to 10 Hz was 3.3 nT. A perming error of 1 /spl mu/T was measured for a wide range of excitation currents.