Cascadable monolithic balanced amplifiers at microwave frequencies

A cascadable monolithic amplifier, where input-output decoupling is obtained through new broad-band, low-loss coplanar directional couplers, is reported. Design data and experimental results are given for the new couplers which are suitable for both hybrid and monolithic circuit applications. The main features of the prototype X-band monolithic balanced amplifier are stressed. Finally, low-loss slow-wave structures for monolithic circuit design are briefly presented.