عبدالحمید زاهدی

This paper presents the design of a Low Noise Amplifier (LNA) using double common-source technique results in wideband input matching. Moreover, to reduce the noise figure, a resistor series to source-bulk substrate resistance is applied. One of the main problems of the common-source structure in LNA design is the narrow-band property. Using the proposed double common-source scheme, the narrow-band problem is solved and the desired wideband attributes can be achieved. In addition, using a resistor series to the source-bulk substrate resistance results in significant noise figure reduction. In the proposed scheme, the gain of LNA in frequency band of 3–12 GHz would be between 14.2 dB and 15.1 dB. Furthermore, the variation of gain in this band is 0.45 dB which is significant. The 3-dB bandwidth of the designed LNA is 10.2 GHz (from 2.4 to 12.6 GHz). The worst case of return loss of input port is
10 dB. The above mentioned series resistor causes the noise figure to decrease and set between 3.47 and 4.12 dB. Using 180-nm TSMC technology, the DC power is 11mW from 1-V supporting voltage.