Replace the inverter with an image rejection mixer
IIn the signal system, the image rejection mixer can effectively suppress the image frequency, improve the anti-interference ability of the system, and at the same time effectively recover the image frequency energy and improve the work efficiency. Based on the introduction of the principle of image interference, a block diagram of an image rejection mixer is presented, which can be used as an image rejection mixer in the receiver and as a single sideband in the transmitter. Modulator. In this paper, the interference analysis of a certain type of downconverter is carried out, and compared with the image rejection mixer, the feasibility of replacing the downconverter with image suppression mixer is proposed.
In recent years, with the rapid development of microwave devices, in the field of communication, the receiving system generally adopts a low-noise amplifier as the front stage, which greatly reduces the noise figure of the system and improves the sensitivity. The effect and effect of the mixer on the receiving system seems to be getting smaller and smaller, but this is not the case. For single sideband systems, especially for single sideband systems with lower intermediate frequencies, image noise can have a significant impact on noise. Therefore, in a single sideband system where the low noise amplifier has a wide frequency band and the intermediate frequency is not high, an image rejection mixer must be used.