Analysis and design of harmonic rejection low noise amplifier with an embedded notch filter

This paper presents the analysis and design of the harmonic rejection (HR) low-noise amplifier (LNA) with the fully passive source degeneration notch filter. The proposed HR LNA provides the rejection for the strong harmonics (3_rd) of the local oscillator (LO) frequencies, where the HR mixer does not provide sufficient HR performance. The proposed 3_rd harmonic notch filter modulates the source degeneration factor and the impedance matching performance thereafter. This effect further helps the blocking of the harmonic signal. The proposed LNA provides 11 dB gain at the fundamental frequency (2.1 GHz) while rejecting the 3rd harmonic component by 37 dBc. Compared to the conventional LNA, the 3rd harmonic notch performance is improved by 23 dB. Additionally, the LNA achieves a minimum noise figure of 3.1 dB, third order input intercept point (I I P₃) of 0.5 dBm, input reflection (S₁₁) below −10 dB from 1.8 GHz–2.3 GHz operational frequency range, and consumed 19 mW of power from a 1.2 V supply.