A phase difference‐to‐voltage converter has been developed in order to measure and to monitor the phase angle ϕ between the rotating magnetic field and the disk magnetization in the recently developed rotating magnetic disk viscometer. The circuit described here shows a very good linearity (the nonlinearity has been experimentally found to be well ≤50 p.p.m.), high resolution (fractional phase changes as low as Δϕ/ϕ≊10−4 can be detected), very high short‐term stability (1/VϕΔVϕ/ΔT ≤10 p.p.m./°C), very good long‐term stability (ΔVϕ/Vϕ ≤50 p.p.m. over several months), and a rapid response even at the low frequencies (0.5–30 Hz) used in the viscometer.
Phase Difference-to-voltage Converter
BORGHESANI, ARMANDO-FRANCESCO
1989
Abstract
A phase difference‐to‐voltage converter has been developed in order to measure and to monitor the phase angle ϕ between the rotating magnetic field and the disk magnetization in the recently developed rotating magnetic disk viscometer. The circuit described here shows a very good linearity (the nonlinearity has been experimentally found to be well ≤50 p.p.m.), high resolution (fractional phase changes as low as Δϕ/ϕ≊10−4 can be detected), very high short‐term stability (1/VϕΔVϕ/ΔT ≤10 p.p.m./°C), very good long‐term stability (ΔVϕ/Vϕ ≤50 p.p.m. over several months), and a rapid response even at the low frequencies (0.5–30 Hz) used in the viscometer.
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