Compact reflective-type phase-shifter MMIC for C-band using a lumped-element coupler

The design and results of an ultra-compact single-load reflective-type mono lithic-microwave integrated-circuit phase shifter at 6.2 GHz for a satellit e radar system is presented in this paper, which has been fabricated using a commercial 0.6-mum GaAs MESFET process. A 3-dB 90 degrees coupler with lu mped elements enables significant circuit size reduction in comparison to f ormer approaches applying microstrip branch line or Lange couplers. Phase c ontrol is enabled using MESFET varactors with capacitance control ratios (C -max/C-min) of only four. Equations are derived to precisely describe the p hase control ranges versus capacitance control ratios for different load co nfigurations to allow efficient optimizations. Furthermore, the design trad eoff between low loss and high phase control range is discussed. Within a p hase control range of 210 degrees, a loss of 4.9 dB +/- 0.9 dB and a 1-dB i nput compression point of higher than 5 dBm was measured for the designed p hase shifter. The circuit I size is less than 0.5 mm(2), which, to our know ledge, is the smallest reflective-type phase-shifter size reported to date.