Abstract: To reduce the noise figure in the tradition low noise amplifier, extend the bandwidth and achieve more precise step accuracy, a RF programmable amplifier with low noise single-ended differential circuit is proposed. The single-ended differential circuit uses the noise cancellation method to reduce the noise figure and uses the capacitance cross technique to extend the bandwidth. The improved source-level follower structure can achieve more precise step accuracy. The circuit is fabricated in 0.18mCMOS process. Under 1.8 V power supply and 170-870 MHz frequency signal input, the circuit achieves a 3.8 dB noise figure. The circuit shows a 55 dB gain control range by 0.8 dB each step. The overall power consumption is less than 14.76 mW, and the die area is 800m 600m . The test result shows that the circuit can provide lower noise figure and cover wider bandwidth while consumes the same current comparing with the tradition structure and the circuit can provide more precise step accuracy.