Quadrature sinusoidal oscillator based on log-domain high-pass and low-pass filters

A log-domain current-mode quadrature sinusoidal oscillator (QSO) based on low-pass (LP) and high-pass (HP) filters is presented. The log-domain QSO is realized by using only 18 NPN transistors and 2 grounded capacitors for achieving low-power and fast response. The proposed oscillator uses a cascade connecting the LP and HP which can be electronically tuned through bias current. Frequency of oscillation can be tuned over a wide-range with a low-power supply as 2V which is suitable for IC production. The power consumption is obtained around 5.5mW at 100μA of bias current. The oscillation frequency is controlled over four decades of frequency. The total harmonic distortion of QSO at 10.63MHz is obtained around 1.25%. The proposed circuit is suitable for high-frequency applications. PSpice simulation confirms the theoretical results. © 2011 IEEE.