A high precision square law detector in digital microwave radiometer

A new square law detector has been developed for digital microwave radiometer. It has a wider dynamic range and a more accurate square law response than has been available in the past. Experimental results show that the voltage sensitivity is higher than 0.9mV/uW and the linearity error is less than 0.3% in the frequency range from 100MHz to 2GHz and power range from -50dBm to -20dBm. Another advantage of the detector is its flatness, by selected a best type of diodes. Detailed detection circuit and measurement system have been given in this paper.