Uncorrelated Phase Noise Cancellation in Intermediate Frequency with a Low-IF Dual-PLL Radar System

In this paper, a new low-IF dual-PLL radar architecture for uncorrelated phase noise cancellation in low-intermediate frequency has been presented. By using an additional mixer between the dual PLLs, a reference signal at the IF frequency is generated with its phase noise correlated to that of the received down-converted IF signal. By introducing IF cancellation through phase and magnitude adjustments of the reference IF signal, the uncorrelated phase noise, which has been existing in the state-of-the-art dual-PLL Doppler radars, can be greatly suppressed in this work. Detailed signal-noise models and analysis are provided to demonstrate the principles. Furthermore, an obvious reduction of the IF noise floor and thus an enhanced S N R have been observed in the experimental results with and without leakage consideration, which well validate the effectiveness of the proposed concept.