Two-stage current-reused variable-gain low-noise amplifier for X-band receivers in 65 nm complementary metal oxide semiconductor technology

In this study, a variable gain low noise amplifier (VG-LNA) working at X band is designed and simulated in 65 nm complementary metal oxide semiconductor technology. A two-stage structure is used in the proposed VG-LNA. Besides, the current-reused technique causes a higher gain without consuming extra power. As an on-chip voltage (V-cnt) is changed, the gain continuously and almost linearly varies. The highest gain is 27.8 dB that can be reduced to 8.3 dB almost linearly and continuously as the control voltage is increased. The lowest value of S11 is -28.2 dB at 10 GHz. Also, NF is <2.75 dB at the operating frequency range; while NFmin = 1.8 dB. The highest value of third-order intercept point is 2.03 dBm that always remain larger than -10.1 dBm. The basic advantage of this structure in comparison with other similar works is that not only the key parameters remain fixed with reduction of gain, but also the operation range of V-cnt is widened from 0.3 V to V-dd in order to extend the gain control range to 19.5 dB. Moreover, these results are achieved in a situation that the proposed VG-LNA draws only 3.9 mA from a 1.2 V.