Fully monolithic integrated even harmonic quadrature ring mixer with an active matched 90 degree power divider for direct conversion receivers

This paper proposes a novel circuit configuration of an even harmonic quadrature mixer for direct conversion receivers. The proposed configuration employs a ring mixer concept for wide-band reception and active matching circuits for a full integration on a small sized GaAs chip. Highly stable quadrature detecting characteristics over LO power variation can be achieved by the proposed active matched 90 degree power divider. A developed 2 GHz MMIC achieves an extremely small chip size of 1.3 mm/spl times/1.85 mm, and good quadrature detecting characteristics with amplitude error within 0.5 dB and phase error within 5 degrees from 1.7 GHz to 2.3 GHz.