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 0.25um BiCMOS technology.  To prove the viability of
this scheme, a single-sideband mixer was implemented along with the
splitter.  Over several chips, an average sideband supression of about
45dBc was obtained.

Based on an 2002 accepted JSSC paper by P. Kinget, R. Melville,
D. Long, and V. Gopinathan. Was also presented at ESSCIRC 2001.