Performance variance of low-noise resonant capacitance bridges with ungapped MnZn ferrite core replacements

Area of Science:

• Electrical Engineering
• Materials Science
• Metrology

Background:

• Precision AC resonant capacitance bridges are crucial for high-precision measurements.
• These bridges often utilize planar printed circuit board transformers with ungapped MnZn ferrite cores.
• Consistency in the performance of multiple bridges is essential for system functionality.

Purpose of the Study:

• To evaluate the noise performance consistency of ungapped MnZn ferrite cores for precision AC resonant capacitance bridges.
• To assess the impact of temperature variations (293 K and 140 K) on core noise performance.
• To compare the performance of cores from the same manufacturing batch and with different batches.

Main Methods:

• Ten SIFERRIT Material N41 cores (TDK) were tested at 293 K and 140 K.
• Noise performance was measured and fitted to a parabolic function.
• Data was scaled for resonant frequency and temperature for comparison.

Main Results:

• At 293 K, weighted mean noise variance was <0.3% (all cores within ±1%); weighted mean noise minimum was 0.3027 aF/√Hz at 85.0 ± 2.7 kHz.
• At 140 K, weighted mean noise variance was <0.6% (90% inclusion band ±1.5%); weighted mean noise minimum was 0.1815 aF/√Hz at 152.7 ± 6.3 kHz.
• Scaled results showed consistency with previous measurements, with discrepancies of 9% (293 K) and 6% (140 K).

Conclusions:

• Ungapped MnZn ferrite cores exhibit excellent and consistent noise performance across multiple units and temperatures.
• The tested cores meet the stringent requirements for high-precision measurement systems.
• The findings support the use of these cores in applications demanding high reliability and performance consistency.