Voltage-mode multiphase sinusoidal oscillators using CBTAs

A voltage-mode multiphase sinusoidal oscillator (MSO) structure using current backward transconductance amplifier (CBTA) is presented. The oscillator can generate n voltage signals (n being even or odd) equally spaced in phase. n+1 CBTAs, n grounded capacitor and a grounded resistor are used for nth-state oscillator. The oscillation frequency can be independently controlled through transconductance (g_m) of the CBTAs which are adjustable via bias currents. The effects caused by the non-ideality of the CBTA on the oscillation frequency and condition have been analyzed. The performance of the proposed circuit is demonstrated on a third-stage MSO by using PSPICE simulations based on the 0.25 μm TSMC level-7 CMOS technology parameters.