Log-domain current-mode third-order sinusoidal oscillator

This paper describes the design of the third-order sinusoidal oscillator based on log-domain filtering concept. The circuit consists of two inverting lossy integrators and one inverting lossless integrator. The circuit employs only NPN-transistors. This proposed circuit can be instantaneously controlled over a very wide frequency range by adjusting bias currents for oscillation frequency which are indicated proposed circuit suitability in high-frequency applications. The oscillation condition and frequency of oscillation can be tuned by bias current. Sinusoidal frequency output can be obtained up to 100 MHz with low THD and low number of transistors. Characteristics of this circuit are simulated using PSpice and they are found in agreement with the theory.