Design And Implementation Of Low Power High Linearity Low Noise Amplifier And Quadrature Mixer

Due to the advantages of anti-noise, anti-interference, anti-multipath fading, DRM (Digital Radio Mondiale) and DAB (Digital Audio Broadcasting) have become the new genetation of broadcasting following the tradition alanalog broadcasting AM and FM. The research of DRM/DAB receiver chip is the emphasis and difficulty of the development of digital broadcast system, and it is of great significance for the development of wireless communication ICs in our country.In this paper, an LNA (Low Noise Amplifier) and a quadrature mixer in DRM/DAB have been designed, based on SMIC’s 0.18-μm CMOS process. The LNA has been designed based on active feedback structure, which can break the tie between input matching and noise figure and increase the flexibility of design. By careful design, the active negative feedback low noise amplifier provides a sufficient gain, a lower noise figure and a good linearity, which meet the application requirements DRM/DAB receiver. Moreover, this kind of inductorless topology significantly saves the area and cost of chip. Then, the quadrature mixer, based on the Gilbert cell mixer, is combined with the DS (derivative superposition) technology to optimize the linearity. Without sacrificing other performance, the quadrature mixer gets a higher conversion gain and a low noise figure.Cadence Spectre tools are used to complete the pre-simulation, layout design and the post-simulation. Acording to the result:within the 150 kHz to 240 MHz band, the LNA with two gain modes,17.73 dB and 13.77 dB, respectively. It has a good input matching feature, the minimum noise figure is 2.72 dB, the minimum input 1-dB compression point is -8.96 dBm and the minimum input 3rd-order intercept point is 1.92 dBm. At the intermediate frequency (IF) of 35 MHz, the mixer has a conversion gain of 6.94 dB, the noise figure is lower than 15.57 dB with 240-MHz input frequency, and the input 3rd-order intercept pointcan reach 17.52 dBm.These post-simulation results of the LNA and the mixer meet the requirements of the design specifications and can be integrated into a DRM/DAB receiver chip after further optimization.