Zero intermediate frequency receiver and method for eliminating DC offset of same

Abstract

The invention discloses a zero intermediate frequency receiver and a method for eliminating the DC offset of the same. The receiver comprises a low-noise amplifier, a mixer, a first variable gain amplifier, an analogue-to-digital converter and a DC offset elimination device. The DC offset elimination device of the receiver combines analogue DC subtraction and digital DC subtraction by adopting an analogue feedback circuit to avoid complexity when an analogue circuit is independently used for DC subtraction, meet the requirement of a broadband receiver on the lowest flexibility and solve the problem that the dynamic analogue signal input range of the analogue-to-digital converter is required not to be wide when the digital DC subtraction is independently used. Experiments show that the DC offset can be relatively more completely eliminated from baseband signals by the method.

Description

technical field [0001] The invention relates to a receiver and a method for eliminating a DC offset thereof, in particular to a zero-IF receiver and a method for eliminating a DC offset thereof, and belongs to the technical field of communication. Background technique [0002] In recent years, the rapid development of wireless communication technologies such as wireless LAN, 3G technology, and Bluetooth has promoted further research on integrated wireless receivers in the GHz frequency range. The radio frequency transceiver (Transceiver) front-end architecture based on these wireless communication standards is mainly divided into superheterodyne and zero-IF. [0003] The traditional superheterodyne architecture has a long history of converting the signal frequency band (RF) to a relatively low intermediate frequency (IF). The intermediate frequency IF is filtered, amplified, converted to baseband, and finally quantized and demodulated. IF signal processing requires IF filt...

AI Technical Summary

Problems solved by technology

[0005] However, everything has two sides, and zero-IF receivers also have their disadvantages: 1) The baseband DC offset introduced during down-conversion reduces the overall dynamic range of the system; 2) Low radiation has more stringent requirements for LO leakage indicators

Then, from the shortcomings of the zero-IF receiver, it can be known that when using this structure, it is necessary to eliminate the baseband DC offset as much as possible and estimate the LO leakage at the transmitter

At present, the technologies for eliminating the DC offset of the baseband mainly include pure analog circuit to remove DC and pure digital to remove DC. However, it is difficult to eliminate the DC offset of the baseband signal if a pure analog circuit is used to remove DC, especially for For a zero-IF receiver that requires low receiving sensitivity and a relatively large DC offset value, it is difficult to meet the requirements of DC removal by using a simple analog circuit. Even if a circuit that meets the requirements can be built, this circuit is very complicated and not suitable for Chip-level implementation; if you use pure digital to remove DC, although the DC can be removed relatively cleanly, the dynamics of the ADC input signal cannot meet the requirements. If the signal is greater than a certain value plus the existing DC offset value, it will be extremely difficult. It is easy to exceed the input signal range specified by the ADC

Therefore, the above two DC removal methods cannot meet the requirements of zero-IF receivers with large signal dynamic range and low minimum receiving sensitivity requirements.

[0006] In summary, it can be known that the zero-IF receiver of the prior art has the problem that the direct current introduced in the down-conversion process is difficult to remove. Therefore, it is necessary to propose improved technical means to solve this problem

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