A 9.8-11.5 GHz quadrature ring oscillator for optical receivers

A 9.8-11.5 GHz quadrature ring oscillator for use in the data clock recovery circuit of optical receivers has been realized in a BiCMOS technology with 30 GHz cut-off frequency. The circuit implementation of the oscillator uses active inductors which provide isolation between the oscillator and cascaded circuits such as buffers and flip-flops. Carrier to noise ratios better than 94 dBc/Hz at 2 MHz offset are measured with 75 mW dissipation and 2.7 V supply voltage. The realized quadrature oscillator achieves a state of the art oscillation frequency over transistor cut-off frequency ratio of 0.38.