A wideband feedback compensated quadrature generator

Abstract

A novel quadrature generator is presented in this paper that exhibits a 40% operating frequency bandwidth. Current circuits do not generally provide quadrature signals over such a wide fractional bandwidth and they are often susceptible to variances in component values, which can shift their operating frequency. In this work, this is resolved with the use of a negative feedback network including a pair of phase shifters and two variable gain amplifiers to actively compensate the imbalances over a large frequency range. Experimental results show a 2GHz bandwidth centered at 5 GHz while maintaining a phase error below 8° and less than 1.5 dB in amplitude error. The circuit, without bonding pads, uses an area of only 0.28mm2.