An Inline RF Power Sensor Based on Fixed Capacitive Coupling for GaAs MMIC Applications

This letter proposes an inline RF power sensor based on fixed capacitive coupling for GaAs MMIC applications. In the design, a certain percentage of the input power coupled by a beam and sensed in a thermopile sensor, where the beam is not required to release to obtain a fixed capacitance for high-power levels and increase the dynamic range. This sensor offers the compatible capability with the GaAs MMIC technology. Measured reflection and insertion losses are <;-24.2 and 0.73 dB at X-band, respectively. Experiments demonstrate that this inline sensor exhibits good linearity of the output response from 1 to 200 mW, and results in the average sensitivity of ~29.5 μV/mW at 10 GHz. The sensitivity increases with the increase of the X-band frequency, with small measurement errors.