Carrier adaptive filtering method and system of zero intermediate frequency, and zero intermediate frequency receiver

Abstract

The embodiment of the invention discloses a carrier adaptive filtering method and a system of zero intermediate frequency, and a corresponding zero intermediate frequency receiver. The method comprises the following steps: de-spreading an I signal filtered by a first FIR filter and a Q signal filtered by a second FIR filter; calculating the errors of the de-spread I signal and Q signal between the coordinates in the planisphere and the ideal coordinates in the planisphere by using an EVM method; and adjusting the coefficients of the first FIR filter and the second FIR filter according to the errors, until both the differences between the coefficients of the first FIR filter and second FIR filter before and after the adjustment are less than the preset threshold. The invention can effectively inhibit zero-frequency components and I / Q mismatch, does not need to interrupt the effective signal, and can be used in a WCDMA downgoing signal or CDMA downgoing signal receiver system.

Description

technical field [0001] The invention belongs to the technical field of communication, and in particular relates to a zero-IF carrier adaptive filtering method and system and a zero-IF receiver. Background technique [0002] In recent years, with the rapid anti-war of wireless communication technology, wireless communication system products have become more and more popular, and have become an important part of the development of today's human information society. The radio frequency receiver is located at the forefront of the wireless communication system, and its structure and performance directly affect the entire communication system. Optimizing the design structure and selecting the appropriate manufacturing process to improve the performance and price ratio of the system is the direction pursued by RF engineers. [0003] The zero-IF receiver has been widely valued because it does not need an off-chip high-Q band-pass filter and can be integrated on a single chip. Spec...

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Problems solved by technology

[0004] But the zero-IF receiver itself also has defects, such as DC deviation, local oscillator leakage and IQ imbalance, etc.

The disadvantage is that a large capacitor is used, which increases the area of ​​the chip

However, this method is obviously not suitable for spread spectrum debugging such as WCDMA. In wideband spread spectrum debugging, the zero frequency and its surrounding areas are occupied by effective signals.

There are also some methods based on independent calibration signals, but these methods have to interrupt the transmission of valid signals to correct for IQ imbalance

For example, use a special signal source to input the receiver to detect the degree of IQ imbalance and then compensate it, so that the signal from the mobile phone cannot be received normally.

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