Common-Base/Common-Gate Millimeter-Wave Power Detectors

The principle of two common base/gate millimeter-wave power detectors is analyzed and validated by experimental results. The detectors have been designed for automatic level control and built-in-test millimeter-wave applications. Closed-form expressions are derived for the transfer characteristic as well as for the noise behavior of each detector. The circuits are fabricated in a BiCMOS 55 nm ( ft/fmax = 320 GHz/370 GHz) process from STMicroelectronics. Each detector occupies an area of 80 × 80 μm² and exhibits a relatively high input impedance at 60 GHz. Measurements show a detection dynamic range larger than 38 dB and a flat response over the 50-66 GHz bandwidth, for both detectors. Common-base detector shows a wider linear detection range than that of the common-gate one. Theoretical computation and computer simulation show that, for square-law detection, the minimum detectable input power (for SNR = 10 dB) is around - 41 dBm for the common-gate detector against - 50 dBm for the common-base one. In their nominal bias conditions, the detectors´ power consumption, under 1.2 V supply voltage, is 90 μW for low input power and it increases to about 800 μW for 8.5 dBm input power. These performances are beyond the current state-of-the-art of millimeter-wave detectors.