This paper describes millimetre wave (mmW) on-wafer power detection using dedicated high frequency diode junction with a cut-off frequency (fc) of 400 GHz, integrated in SiGe BiCMOS 55 nm technology from STMicroelectronics. This extraction was performed in order to develop fully integrated power detection for transistor or MMIC large signal characterisation on mmW frequency range above 110 GHz. The power detection is performed by biasing the diode in its forward regime. That allows us to obtain an adjustable voltage responsivity (gamma) between 426 V/W and 3836 V/W at 320 GHz on the unmatched diode. In this configuration the corresponding dynamic range can be adjusted depending upon the configuration.