Digitally Controlled, 6 Bit, MMIC Phase Shifter for SAR Applications

A 6-bit, digitally controlled phase shifter is described. Details of the design, manufacture and measured results are presented. The single chip Monolithic Microwave Integrated Circuit (MMIC) covers the 4.9 ¿5.7GHz band with an rms phase error of 5.5°. If instead of assuming ideal binary weighted bits, the most appropriate phase states are selected then the control of the chip is optimised. This results in an optimised rms phase error of 1.9°. Extremely low levels of insertion loss variation with phase state make this chip particularly useful for Synthetic Aperture Radar (SAR) applications.