Analysis and design of a square-law detector based on multiplier for high linearity radiometer

Radiometers are used in a various number of measurements applications. The output detector is the main element in the radiometer which determines its linearity and dynamic range. In this paper, the square-law detection principle of Schottky diode and multiplier is introduced. The multiplication detection module and the amplifer-filter circuits are designed. The multiplication detector takes the analog multiplier as the core, and the differential circuit is used at the signal input. The output linearity of 0.99999 is achieved in the bandwidth of 50 MHz ~ 2GHz and the dynamic range of -16dBm ~ 4dBm. Compared with the diode detector, the multiplication detector has the advantages of large effective bandwidth, wide dynamic range, high linearity and good stability.