High-resolution analog quadrature sine oscillator for lock-in amplifiers applications

This paper introduces a high-precision sine quadrature oscillator based on single resistor-controlled oscillator configuration. It presents advantageous features such as independent control of the oscillation condition regarding to its oscillation frequency, a wide and precise frequency variation and amplitude stability in the whole operating range. To control frequency tuning, it includes an innovative technique which adds R-2R based Digital-to-Analog Converters as control elements. This new approach overcomes the frequency tuning limitation presented by single resistor-controlled oscillators due to tolerance limitations of passive elements. Experimental results validate the proposed configuration, confirming its enormous possibilities in a wide field of applications, such as our driving application, especially, in those related to lock-in amplifiers.