UWB LNA with out-band interference rejection exploiting multistage matching circuit

Two ultra-wideband (UWB) low-noise amplifiers (LNAs) with out-band interference rejection in front-end MOS device in triode mode are presented. In this scheme, a combination of coupled inductors is employed in the input stage of the proposed LNAs. While this stage has no DC power consumption, it is possible to easily reject out band interference. In order to increase power gain of the circuit two stages are added as an amplifier to each circuit. The first UWB LNA based on this new stage is proposed in 0.18 μm technology. Simulation results show S
_{21, MAX}
and NF
_min
of 19.7 dB and 2.17 dB in 3.1-10.1 GHz, respectively. In order to improve the input reflection coefficient in high frequency band and extend bandwidth of LNA up to 10.6 GHz, new matching circuit based on band pass filter is utilized as well. Weak inversion and zero bias MOS is used in the proposed matching circuit. Second UWB LNA based on this new structure is proposed in 0.18 μm technology. Hence, simulation results show S
_{21, MAX}
and NF
_min
of 19.4 dB and 2.35 dB in 3.1-10.6 GHz, respectively. Therefore, the proposed LNAs reject out-band interference over 2.4-2.5 GHz at least 17.4 dB and 18.2 dB, respectively, compared to maximum gain. This is while both circuits consume 10.93 mW DC power from 1.8 V supply voltage.