An X-Band Sampled-Line Impedance Sensor in 250-nm GaAs

This paper describes the design and characterization of an X-band MMIC sampled-line impedance sensor. The network is intended for integration into a power amplifier (PA) in applications where load impedance varies, for example in phased arrays. Scalar power detectors placed along a transmission line perform a complex measurement of the load reflection coefficient. The X-band prototype in 250-nm GaAs demonstrates the ability to implement this technique in MMIC technology, as a step towards integration into a MMIC PA. In addition to characterization of the impedance measurement for reflection coefficient magnitudes up to 0.6, the sampled line is compared to a standard 50-ohm line in terms of loss, and a standalone sampler is measured.