Synthetic inductance standards made up of capacitances and gyrators

Inductance standards currently available are made up of toroidal inductors, i.e. coils of wire wound around a toroidal non-magnetic core. The maximum inductance achievable is 10 H, while modern LCR meters offer measurement ranges up to more than 10 kH. Due to their winding capacitance and wire resistance, toroidal inductors exhibit quite large parasitic elements that restrict the operating frequency due to resonances. Using a gyrator in conjunction with a capacitance standard creates a synthesized inductance which can exhibit values up to hundred of kilohenrys. Optimizing the gyrator's parameters leads to much lower parasitics and thus an extended usable frequency range even for inductances available as toroidal inductors. Furthermore, the physical size of a gyrator circuit is much smaller than that of a toroid, which simplifies thermoregulation and transportation.

I. Introduction

Toroidal inductors suffer from several imperfections: •

winding capacitance

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winding resistance

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temperature dependence

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bulky dimensions