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Method and device for eliminating DC shifting of radio frequency receiver

A technology of radio frequency receiver and DC drift, which is applied in the field of communication, can solve the problems affecting the demodulation performance of the receiver, reduce the dynamic range of the receiver, etc., and achieve the effect of reducing the impact and improving the performance

Active Publication Date: 2008-11-05
ST ERICSSON SEMICON BEIJING
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Problems solved by technology

However, the DC drift signal inherent in zero-IF becomes a major drawback of this receiver architecture
The impact of the DC drift signal on the receiver includes saturating the AD converter and reducing the dynamic range of the receiver will affect the demodulation performance of the receiver

Method used

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  • Method and device for eliminating DC shifting of radio frequency receiver
  • Method and device for eliminating DC shifting of radio frequency receiver
  • Method and device for eliminating DC shifting of radio frequency receiver

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Embodiment Construction

[0022] 下面将结合附图及具体实施例对本发明作进一步说明。

[0023] 本发明的射频接收机直流漂移的消除方法,需要在射频接收机的校准模式生成并保存直流漂移信号的直流校准表,该直流校准表是该射频接收机在不同增益下对应的直流漂移信号的直流校准表;在射频接收机的工作模式,通过查表的方式,消除不同增益对应的直流漂移信号。

[0024] 首先,在射频接收机校准模式,生成并保存直流漂移信号的直流校准表,所述直流校准表由一定数量的对应不同增益值的表元构成,如 figure 1 shown, including the following steps:

[0025] 步骤S100:准备工作,设定射频接收机的接收增益序列。本发明实施例的射频接收机直流漂移的消除方法,需要根据实际情况,将射频接收机的接收增益的取值范围分段,得到射频接收机的一个接收增益序列,AGC(i)(i=1,2,...,N),在初始状态,取i=1。本发明的射频接收机直流漂移的消除方法,射频接收机的接收增益的分段方法,需要在校准时间和直流漂移的推算精度之间进行折中选择。如果分段越细致,则得到的推算精度就越高,同时也加长了进行校准和查找校准表的时间复杂度。在实践中,可以根据射频接收机的接收增益变化与直流漂移变化趋势之间的关联关系,确定接收增益的分段。

[0026] 步骤S110:射频接收机接收用于校准的射频信号,并将其下变频为基带信号。该射频信号功率恒定,优选的为一个和载波频率有一定频偏的单音信号(即正弦波),之所以要与载波信号有一定的频偏,是为之后的处理步骤中能够更容易更准确的推算直流漂移信号的幅值。该单音信号,既可以由外部信号源发射,也可由射频接收机自身内置的发射模块发射,并由射频接收机自身的信号接收模块接收。

[0027] 其中,该单音信号在时域可以表示为:

[0028] S rf =A rf cos(2π(f c +f cali )) (1)

[0029] 公式(1)中,A rf 为信号的幅度,f c 为接收机载波频率,f cali 为偏移载波信号的频率,如 figure 2 所示,射频接收机接收到的射频信号(包括单音信号)经带通滤波器(BPF)和低噪声放大器(LNA)放大后,与互为正交的两路本振信号(LO)混频,分别产生同相和正...

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Abstract

A radio frequency receiver direct current drift cancellation method, generates and stores direct current calibration tables corresponding to different receiver gains by receiving radiofrequency signals for calibration and passing through the FFT arithmetic, in the calibration mode of the radio frequency receiver; executes direct current drift cancellation to the radiofrequency signals by looking for the stored direct current calibration tables, in the work mode. The invention also discloses a radio frequency receiver direct current drift cancellation apparatus. The invention can be applied to all radio frequency receivers that can produce direct current excursion, the method can furthest decrease the affect of the direct current drift to the performance of the radio frequency receiver.

Description

technical field [0001] 本发明涉及一种通信技术,尤其与一种消除射频接收机直流漂移的方法和装置有关。 Background technique [0002] 零中频(Zero IF)或直接变换(Direct-Conversion)接收机具有体积小、成本低和易于单片集成的特点,正成为射频接收机中极具竞争力的一种结构。优化设计结构和选择合适的制造工艺,以提高系统的性能价格比,是射频工程师追求的方向。由于零中频接收机具有体积小、成本低和易于单片集成的特点,已成为射频接收机中极具竞争力的一种结构,在无线通信领域中受到广泛的关注。 [0003] 但直流漂移信号是零中频结构接收机的主要缺陷,直流漂移信号的产生和来源主要有以下几个方面: [0004] 一、静态的直流漂移(或称直流偏差),静态的直流漂移来自于芯片制造工艺失配(例如混频器的增益不同),失配导致的直流偏差产生于正交解调器和 / 或可变增益放大器(Variable Gain Control,简称VGA),正交解调器输出的直流漂移本身并不会引起接收机故障和性能的下降。然而,由于VGA电压空间限制,当VGA在高增益模式下运行,其增益高达60dB时,几毫伏的直流漂移就足以减小信号摆幅或使VGA饱和,从而降低接收机有效的动态范围。其他因素还有基带放大级固有的直流漂移以及这种直流漂移随温度的漂移等。所以在做基带放大部分的设计时,要保证该部分电路能提供足够的增益,同时也要保证这个增益不能过大,因为如果基带部分增益过大,那么尽管造成的漂移可以被修正,但这种漂移可能会继续漂移,而必须进行额外的补偿。 [0005] 二,本振自混频,来自于本振信号从混频器本振到RF端口,由于混频器LNA的输入端与本振端口的信号隔离不是理想的,在LNA和混频器的输入端出现的泄漏信号与本振自身混频,从而在基带I / Q输出端产生直流成分通过整个信号链路,这种现象叫做自混频。本振信号经过天线泄漏到空间,形成对邻道的干扰。本振泄漏在超外差式接收机中不容易发生,因为本振频率和信号频率相差很大,一般本振频率都落在前级滤波器的频率以外。外部的强干扰信号进入混频器后的自混频在基带I / Q输出产生直流成分。当自混频随时间发生变化时,直流偏差问题将变的十分复杂。这种情况可以在下面的情况下发生:当泄漏的本振信号经天线发射出去后又...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B1/10H04B1/30H03D7/00
Inventor 于雷李济水
Owner ST ERICSSON SEMICON BEIJING
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