A compact passive low-noise amplifier(pLNA) with an N-path 1:3 transformer is demonstrated. Consisting of only switches and capacitors, the N-path 1:3 transformer offers a passive voltage gain and high-Q bandpass filtering in a smaller area than the step-up spiral transformer. The proposed 4-path 20MHz-bandwidth pLNA realized in 55-nm CMOS occupies only a 0.09mm2 active area and consumes 0.7-3.1mW between 0.2GHz to 1.6GHz. The post-layout simulations show that the proposed pLNA achieves a 6.2-8.8dB passive voltage gain, 2.31-3.68dB noise figure(NF), 5.04-14.17dBm in-band(IB) inputreferred third-order intercept point(IIP3), and 24.52-27.16dBm out-of-band(OOB) IIP3 at an 80MHz offset.