A multilayer planar inductor based proximity sensor operating at 4.2 K

Sagar, Pankaj; Gour, Abhay Singh; Karunanithi, R.

doi:10.1016/j.sna.2017.07.042

Cited by 9 publications

(5 citation statements)

References 11 publications

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“…have an added adantage that these oscillators have also been shown to operate at 4.2 K without much change in its characteristics as shown by P. Sagar et al, [15]. A detailed study of design of these circuits have been presented in M. Haque et al, [12].…”

Section: Jinst 13 T08006mentioning

confidence: 99%

“…Beyond a saturation bias voltage, the frequency becomes almost independent of bias voltage and is shown in figure 3(b). Device details for the inverter IC used in the cryogenic LC oscillator is explained in detail in P. Sagar et al, [15].…”

Section: Condition For Invariance Of Frequency With Series Resistance...mentioning

confidence: 99%

“…Oscillator circuits are much simpler to design and usually contain a smaller number of components [12][13][14]. It has been shown in [9,15] that oscillator circuits can be used as the variable conversion circuits for cryogenic eddy current sensors. P. Sagar et al, [15] also showed that LC oscillators can work efficiently even at 4.2 K. Thus oscillators along with sensing element can be made into an integrated sensor package operating at cryogenic temperatures which eliminates the need for long interconnectors and the associated errors.…”

Section: Introductionmentioning

confidence: 99%

“…It has been shown in [9,15] that oscillator circuits can be used as the variable conversion circuits for cryogenic eddy current sensors. P. Sagar et al, [15] also showed that LC oscillators can work efficiently even at 4.2 K. Thus oscillators along with sensing element can be made into an integrated sensor package operating at cryogenic temperatures which eliminates the need for long interconnectors and the associated errors. There is also an added advantage that the 2018 JINST 13 T08006 useful information (sensed parameter) is contained in the frequency and not voltage [13,14,16].…”

Section: Introductionmentioning

confidence: 99%

“…By utilizing two oscillators in tandem, we can determine both real and imaginary parts of the eddy current sensor impedance to a high degree of accuracy. Here, a planar multilayer PCB based coil is used as the sensing element which has been explained in P. Sagar et al, [15]. The sensor is tested by measuring the change in impedance that occurs when a Nb target is placed at specific distance and is allowed to cool down to cryogenic temperature (77 K).…”

Section: Introductionmentioning

confidence: 99%

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A technique for measuring impedance of cryogenic eddy current sensors using dual switched oscillators

2018

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Electrical conductivity measurement using an eddy current sensor requires measuring the absolute change in the impedance of the sensing coil. There have been many different attempts at this by using phase sensing circuits, utilizing impedance analyzers etc. This work utilizes two different oscillator circuit (LC oscillator using an unbuffered inverter and Relaxation Oscillator) to determine the change in impedance of the coil. The LC oscillator is designed in such a way that the circuit is insensitive to change in the series resistance of the sensing coil and hence, only a function of the inductance of the coil. Once the inductance of the coil is determined, a relaxation oscillator is used in an operating region in which the output frequency is a strong function of the series resistance of the coil. This switched oscillator circuit technique is used to determine the impedance of a cryogenic sensing coil at 295 K and 77 K with a Niobium (Nb) target kept at specific distance. Experimental data is compared with that of an impedance analyzer circuit and measurement errors are presented.

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Section: Jinst 13 T08006mentioning

confidence: 99%

Section: Condition For Invariance Of Frequency With Series Resistance...mentioning

confidence: 99%