Lock-in amplifier error estimation and correction in frequency sweep measurements

M.O. SONNAILLON, F.J. BONETTO

REVIEW OF SCIENTIFIC INSTRUMENTS

American Institute of Physics

Lugar: Mellville, New York; Año: 2007 vol. 78 p. 1470101 - 1470107

0034-6748

Error prediction and error correction techniques for lock-in amplifiers (LIA) working with time-varying reference frequency are proposed in this paper. The reference frequency is swept within a given spectrum in order to measure the frequency response of a system. The continuous variation of the reference frequency produces a measurement error that depends on three factors: the sweep speed, the LIA output low-pass filters and the frequency response shape of the measured system. The technique proposed to predict the measurement errors is based on the final value theorem of the Lapace transform. The correction technique uses a double-sweep measurement. A mathematical analysis is presented, validated with computational simulations and experimental measurements.