Noise figure analysis of beamforming systems

The effect of Low Noise Amplifier (LNA) and power combiner on the overall noise figure of a receiver chain are analyzed and presented for a typical receiver system employing analog and digital beamforming network configuration. The analysis of noise figure is carried out under single and multichannel receiver configurations (2 to 256 antenna elements) for phased array and MIMO antenna systems. Results are presented for noise figure at each subsection of the receiver blocks. Which clearly demonstrate that the noise figure of the receiver chain is predominately controlled by the position of the LNA and power combiner. Subsequently, the overall noise figure is also presented for three typical configurations comprising of: 1. Signals are combined, amplified and down-converted. 2. Signals are amplified, combined and down converted. 3. Signals are first amplified and down converted before combining. For an antenna array with a LNA of 3 dB noise figure irrespective of its size, the 2nd and 3rd configurations give 1 dB overall improvement.