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Digital system for image rejection of low-intermediate-frequency receiver and implementation method thereof

A low-IF receiver and image suppression technology, applied in transmission systems, electrical components, etc., can solve problems such as the impact of communication quality

Active Publication Date: 2015-12-23
GUANGZHOU RUNXIN INFORMATION TECH +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

If the mismatch is serious, the communication quality will be seriously affected

Method used

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  • Digital system for image rejection of low-intermediate-frequency receiver and implementation method thereof
  • Digital system for image rejection of low-intermediate-frequency receiver and implementation method thereof
  • Digital system for image rejection of low-intermediate-frequency receiver and implementation method thereof

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Embodiment Construction

[0052] Hereinafter, the present invention will be further described with reference to the drawings and specific implementations:

[0053] The IQ mismatch introduced by the mixer can generally be represented by the following model:

[0054] x LO (t)=cos(ω LO t)-g*sin(ω LO t+θ)=K 1 *exp(-jω LO t)+K 2 *exp(jω LO t)

[0055] among them, K 1 = 1 + g exp ( - j θ ) 2 , K 2 = 1 - g exp ( j θ ) 2

[0056] Assuming that the ideal baseband signal is d(t), then after the RF signal r(t) passes through the mismatched mixer, the resulting mismatched signal can be expressed as:

[0057] x(t)=K 1 *d(t)+K 2 *d * (t)

[0058] Where d * (t) is the conjugate signal of d(t). Converted to frequency domain, due to mixer mismatch, resulting in signal d * (t) An image frequency symmetrical to the baseband signal is produced. The image frequency is the result of IQ mismatch. If the image frequency is suppressed, the IQ mismatch will be ...

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Abstract

The invention discloses a digital system for image rejection of a low-intermediate-frequency receiver and an implementation method thereof. The digital system comprises a direct-current calculation module, a first subtractor, a conjugated calculation module, a power calculation module, a self-adaptive filter calculation module and a plurality of band-pass filter modules; the direct-current calculation module is used for receiving I and Q data and outputting I0 and Q0 data; the first subtractor is used for receiving the I and Q data and the I0 and Q0 data so as to obtain I1 and Q1 data; the conjugated calculation module is used for receiving the I1 and Q1 data so as to obtain I2 and Q2 data; the power calculation module is used for receiving the I1 and Q1 data so as to obtain IQ-POW data; the self-adaptive filter calculation module is used for receiving the I1, Q1, I2, Q2 and IQ-POW data so as to obtain I4 and Q4 data; and the plurality of band-pass filter modules are used for receiving the I4 and Q4 data so as to obtain I5 and Q5 data. IQ mismatch can be improved obviously and stably although the digital system disclosed by the invention has a relatively simple structure.

Description

Technical field [0001] The present invention relates to the field of wireless communication technology, and in particular to a digital system suitable for but not limited to image rejection of low-IF receivers. Background technique [0002] The radio frequency part of a modern digital wireless communication receiver system generally includes the following analog circuits: band-pass filter, mixer, low-pass filter, gain control (AGC), and analog-to-digital converter (ADC). When the system uses the modulation method of in-phase (I) and quadrature (Q) signals, then we need to generate I and Q signals separately from the modulation signal near the high-frequency carrier at the RF end through mixing and filtering ( Such as figure 1 Shown). Ideal IQ signal, the signal amplitude is the same, the phase difference is 90 degrees (such as figure 2 Shown). However, when the analog circuit is implemented on the chip, due to the IQ link corresponding circuit in different physical positions, ...

Claims

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Application Information

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IPC IPC(8): H04B1/16
Inventor 陈焰强王日炎林汉雄万为陈红林
Owner GUANGZHOU RUNXIN INFORMATION TECH
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