Zero intermediate frequency direct current compensation circuit and method

A technology of zero intermediate frequency and DC component, which is applied in the field of analog signal processing, can solve the problems of large signal loss, the inability of DC signals to pass through DC blocking capacitors, complex structures, etc., and achieve the effect of avoiding amplifier saturation

Inactive Publication Date: 2013-12-18
WUHAN BINHU ELECTRONICS
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  • Abstract
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Problems solved by technology

Radio frequency cancellation needs to consider the radio frequency components from multiple sources, and the structure is complex
Digital cancellation needs to consider the problem of DC component amplification saturation before the ADC collects data, which cannot provide sufficient gain
AC cancellation has great limitations, and it is only suitable for high-frequency intermediate frequency signals, because the characteristic of capacitors is "blocking DC, passing AC", and DC signals cannot pass through DC blocking capacitors. After the signal loss is greater

Method used

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Embodiment Construction

[0019] Specific embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0020] Such as figure 1 Shown is a functional block diagram of the zero-IF DC cancellation technology of the present invention. The zero-IF signal generated after down-conversion is directly input to the voltage follower Ⅰ, and then the level of the zero-IF is raised by about 0.7V through the adder, and then the power is divided into two channels, one is directly sent to the differential amplifier, and the other is sent to the effective value The converter converts the DC to the differential amplifier. The two signals are subtracted by the differential amplifier to obtain the AC component of the zero-IF signal, that is, the useful signal.

[0021] The input terminal of the voltage follower Ⅰ is directly connected to the intermediate frequency output port of the down-conversion mixer. Because the input impedance of the voltage followe...

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Abstract

The invention belongs to the technical field of analog signal processing, and particularly relates to a circuit and method which can conduct direct current compensation on the intermediate frequency end of a zero intermediate frequency receiver to remove direct current components generated during frequency mixing in real time. According to the zero intermediate frequency direct current compensation circuit and method, only alternating current components are left in intermediate frequency signals by removing the direct current components generated by continuous wave frequency conversion in real time, accordingly, sufficient gain can be provided, and the zero intermediate frequency signals are amplified to be within a scope suitable for A / D converter collection.

Description

technical field [0001] The invention belongs to the technical field of analog signal processing, and in particular relates to a circuit and method for performing DC cancellation at an intermediate frequency end of a zero-IF receiver and removing DC components generated during frequency mixing in real time. Background technique [0002] The basic working principle of the zero-IF receiver is: the radio frequency signal and the local oscillator with the same carrier frequency are directly converted to zero-IF after a down-conversion, and then the useful signal in the zero-IF signal is extracted through amplification and low-pass filtering. [0003] Compared with the traditional superheterodyne receiver, the RF signal of the zero-IF receiver has no image frequency and does not need an image rejection filter. The basic frequency signal after frequency conversion is at a low frequency (generally lower than 10kHz), and the amplifying circuit can use an ordinary operational amplifie...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B1/30H04L25/06
Inventor 沈金成韩喆苑凤雨
Owner WUHAN BINHU ELECTRONICS
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