High-frequency log-domain current-mode multiphase sinusoidal oscillator

This study describes the design of a multiphase sinusoidal oscillator (MSO) based on log-domain filtering concept. The circuit is a direct realisation of a first-order differential equation for obtaining the inverting and non-inverting low-pass filters. Each low-pass filter comprises only a grounded capacitor and four transistors. The proposed MSO can be instantaneously controlled over a very wide frequency range by controlling the current for the oscillation frequency and oscillation condition which indicates the proposed MSO´s suitability in high-frequency applications. A validated bipolar junction transistor (BJT) model is used in SPICE simulation operated from a single power supply as low as 2.5´V. The oscillation frequency is controlled over four decades of frequency. The total harmonic distortions for three phase (11.5´MHz) and four phase (7´MHz) are, respectively, obtained around 2.4 and 2.2´ which enables them to be fully integrated in telecommunication systems. The power consumption is around 5.5´mW for 100´´A bias current. Moreover, experimental results of three-phase MSO are included.