An MHMIC K-band direct conversion demodulator in CPW

This paper presents results on a miniature hybrid microwave integrated circuit (MHMIC) direct frequency conversion demodulator in coplanar waveguide (CPW) for in-phase/quadrature (I/Q) applications at the 20 GHz radio-frequency (RF) band. The 4×7 mm² converter was fabricated using flip-chip GaAs Schottky diodes in a single balanced configuration. It provides in-phase and quadrature outputs with an amplitude balance of better than 1 dB, and a phase balance better than 4.2° over the RF range (20.2 to 21.2 GHz) and the IF range (dc to 200 MHz). To the author´s knowledge, the performance and size reached by this circuit is equal or better than comparable circuits of similar topology that use more expensive fabrication processes.