GaAs MMIC wide-band 4-way phase splitter

A MMIC 4-way phase splitter has been designed with phase and amplitude errors less than 20 and 0.5 dB respectively over the 0.7÷3 Ghz band. The circuit consists of a 2nd order all-pass RC network and a pair of differential chains which provide four signals with 0°, 90° 180° and 270° relative phase shifts and equal amplitude. Passive all-pass networks were studied decades ago, but their wide-band, tolerance-resisting behavior hasn´t been proved until their monolithic implementation. On the other hand, MMIC GaAs FET´s differential amplifiers have been less studied and a new systematic and efficient design technique has been developed and applied to this module. The circuit, with dimensions of 1700×2200 ¿m, has been fabricated using the GEC-Marconi GaAs foundry F20 process and the measurements confirm its good properties over the entire frequency band.