A precise 90/spl deg/ quadrature OTA-C VCO between 50-130 MHz

We present a VLSI continuous time sinusoidal OTA-C quadrature oscillator fabricated in a standard double-poly 0.8 /spl mu/m CMOS process. The oscillator is tunable in the frequency range from 50-130 MHz. A symmetric topology assures that the two phases produced by the oscillator present an extremely low phase difference error (less than 2/spl deg/ over the whole frequency range). A novel current mode amplitude control scheme is developed that allows for very small amplitudes. Experimental results are provided.