A Ka-Band Series Structure Switchable Power Detector System

In this letter, a Ka-band series structure switchable power detector (PD) system equipped with a switchable transformer is proposed for switching detected regions at different input powers. To simultaneously achieve high gain and save dc power, the main RF path is included in a four-stage limiting amplifier (LA) that relies on the double-transformer-coupling (DTC) and current re-used (CR) technique. By switching different detectable paths containing the switchable transformer and PD, the detectable region is changed to a different power region. At a log error of ±1 dB, the measured results indicate that the minimum detectable power (MDP) and dynamic range (DR) are -42 dBm and 49 dB, respectively, at 26 GHz. In the four modes, the measured peak slope values are 30/35/36/34 mV/dB, respectively. At a supply voltage of 1.2 V, the dc power of the PD system is 8.4 mW. These results indicate that, compared with amplifier-based PD systems, the proposed system has a better MDP and DR, and the lowest dc power.