Background: Multipoint observations of plasma waves are essential for separating spatial and temporal variations of\na plasma turbulence. Miniaturization and high environmental (temperature and radiation) robustness are key requirements\nfor scientific instrument design toward a sensor network consisting of palm-sized probes. With increasing these\ndemands, a preamplifier for the 3-axis loop antenna of an electromagnetic sensor probe has been developed by\nusing application-specific integrated circuit (ASIC) technology with a 0.25-Ã?¼m complementary metal-oxide-semiconductor\nprocess.\nFindings: In the present study, a new temperature compensation method is proposed by using the open-loop gain\nof the ASIC preamplifier with a bandgap reference (BGR) circuit. Usually, the gain is characterized by the closed-loop\ngain, which is governed by the accuracy of the polysilicon resistances in a chip. The open-loop gain is characterized\nby the effective transconductance of the ASIC preamplifier, which often has a negative temperature dependence.\nThe temperature dependence of the gain can be dramatically improved by using the temperature-compensated\nBGR circuit to cancel out the negative dependence of the transconductance. The temperature dependence of\nthe gain was about âË?â??0.01 dB/ââ??¦C in the frequency range within the closed-loop bandwidth. On the other hand, the\ntemperature dependence of the gain at 60 kHz operating with the open-loop gain was improved from âË?â??39 Ã?â?? 10âË?â??3\nto âË?â??2.6 Ã?â?? 10âË?â??3 dB/ââ??¦C by using the temperature-compensated BGR circuit. Moreover, the radiation robustness for the\ntotal ionizing dose (TID) level is evaluated by irradiation with gamma rays from cobalt-60. The ASIC preamplifier is not\nsensitive to TID effects when a thin gate oxide is used. The ASIC preamplifier showed a high radiation tolerance to at\nleast a total ionizing dose level of 400 krad(Si). Finally, the effectiveness of the ASIC preamplifier is evaluated on the\nbasis of a virtual sounding rocket experiment using theoretical calculations of LF standard electromagnetic waves.\nConclusions: Fundamental issues (miniaturization, low-noise performance, and high environmental robustness) are\nsolved by the presented ASIC preamplifier. The success in developing the high robustness ASIC preamplifier leads to a\nfuture mission using a lot of palm-sized probes in space.
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