Sub-threshold based power detector for low-cost millimeter-wave applications

This article presents a power detector proposed for low-cost millimeter-wave applications. Thus, the detector uses MOSFET transistor in sub-threshold region in order to realize the signal rectification benefiting from the natural exponential characteristics of MOS transistor in this regime. The detector was designed using the BiCMOS 55 nm technology from ST-Microelectronics. Thanks to this technology, the bipolar version of the detector has also been designed allowing comparison of these two cells. Each of them consume only 30 μW with an 80μm × 80μm area. Theoretical analysis and simulation results demonstrate the advantage of MOS detector in terms of input impedance which reduces the impact of the detector on the device under test (DUT). However, the bipolar detector provides faster responses due to its higher current capability. The MOS based detector has a response time of 1 ns. Its detection range and sensitivity are 20 dB and -18 dBm respectively, in the 50 GHz to 90 GHz frequency band, and are limited by the interconnections parasitic. The design and optimization steps are described in order to provide a general methodology to design high performance power detectors.