Wide tuning range quadrature VCO using coupled multivibrators

Two multivibrators are coupled to produce a quadrature current-/voltage controlled oscillator with wide frequency tuning range (which can be wider than one decade). The tuning range, the achievable frequency of oscillation and the synchronization transients are investigated by simulations. The influences of mismatches of timing capacitors and charging currents on synchronization are also investigated. The results of simulations confirm the potential of the proposed VCO for RF applications.