Amplitude estimation for near-sinusoidal oscillators by using a modified Barkhausen criterion: Research Articles

By using an approach based on the Taylor/Volterra series, nonlinear amplifier characteristics can be introduced into the Barkhausen criterion in order to estimate the amplitude for near-sinusoidal oscillators. The characteristic equation is similar to the 1st-order determining equation obtained by Chua. This new method includes all desirable features of Chua's equation and lets us generalize the linear approach directly to a nonlinear one without losing the mathematical simplicity of the Barkhausen criterion. It also allows us to determine the oscillation amplitude with a desired accuracy. Moreover, this method investigates the influence of the feedback factor and the voltage supply on the oscillation amplitude. Employing only the 3rd-order nonlinearity of the amplifying element, the amplitude of the oscillation predicted by the modified Barkhausen criterion was compared to the one estimated using the transient analysis of SPICE, the harmonic balance analysis of Serenade, and by measurements. The amplitudes obtained by these four approaches for several feedback factors and supply voltages are in good agreement. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.