Abstract: The design of a sort of balanced low-noise amplifier used for TMA is presented in this paper.By using balanced technology and micro-3dB hybrid coupler,the performance of the amplifier is improved and the size of the circuit is reduced significantly.The design start with the computing of the DC operating point and the designing of matching network,then,the pcb-layout is given.The ADS co-simulation was adopted in the circuit design,so that the results can approach the measured results more than that of the practical circuit.Finally,the simulation shows,when operates 800 ~1000MHz,the noise factor is lower than 1dB and the power gain is about 15dB.In addition,the input and output VSWR of the amplifier are lower than 1.2.