An injection locking scheme for precision quadrature generation

We describe a novel quadrature splitter based on injection locking a cascade of ring oscillators to a single phase reference clock. The output signals are in accurate quadrature with low phase noise over a wide bandwidth. This scheme operates at a high signal frequency and is inherently insensitive to the shape of the reference clock waveform. Experimental results at 2.7 GHz are reported for a prototype implementation in 0.25µn BiCMOS technology. To prove the viability of this scheme, a single-sideband mixer was implemented along with the splitter. Over many chips, a considerable improvement in sideband rejection was observed from the state of the art.