[en] This paper reports on a conventional SIS mixer, which is pumped by a single frequency local oscillator (LO) functions as a phase-insensitive linear amplifier and may achieve a noise level near the quantum limit of one-half photon added noise per unit bandwidth. A phase sensitive linear amplifier may have less noise than this quantum limit. The authors attempt to beat the quantum noise limit with an SIS mixer by employing a two-LO technique which makes the mixer's gain dependent upon the phase of the incoming signal The authors experimentally demonstrated the phase sensitive gain of our two-LO mixer, the gain variation from maximum to minimum is more than 20 dB. The authors also present theoretical predictions of the noise of the two-LO mixer