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 SNR have been observed in the experimental results with and without leakage consideration, which well validate the effectiveness of the proposed concept.