Application method for frequency synthesizer in OFDM system

A technology of frequency synthesizer and application method, which is applied in the direction of multi-frequency code system, automatic power control, electrical components, etc., can solve the problems of quantization error, ROM storage data error, frequency synthesizer not involved in OFDM system, etc. Achieve the effects of reducing frequency deviation sensitivity, good phase noise characteristics, and high frequency resolution

Inactive Publication Date: 2006-09-27
南京东大宽带通信技术有限公司
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Problems solved by technology

However, OFDM technology also has defects: it is very sensitive to frequency offset and phase noise; the peak-to-average power ratio is relatively large, and the increase of this ratio will reduce the efficiency of the RF amplifier
The non-ideal characteristics of DAC include: differential, integral non-linearity, peak current during D/A conversion, limited con

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  • Application method for frequency synthesizer in OFDM system
  • Application method for frequency synthesizer in OFDM system
  • Application method for frequency synthesizer in OFDM system

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Embodiment Construction

[0035] refer to figure 1 block diagram and figure 2 The disclosed design circuit diagram of the present invention, the frequency synthesizer applied to the OFDM system is composed of a direct frequency synthesizer, a low-pass filter, a phase-locked loop chip, an active low-pass filter, a voltage-controlled oscillator, a microprocessor and so on. Among them, the microprocessor realizes the control of the direct digital frequency synthesizer, and appropriately modifies (increases or decreases) the control word output to the DDS according to the user's requirements for frequency deviation, so as to achieve the purpose of output frequency adjustment. When the vibration range is around 2GHz and the frequency resolution is 0.05Hz, it still has good phase noise characteristics. Because the output signal of DDS has many spurs, in order to ensure the phase noise index of the local oscillator, an elliptic low-pass filter with good performance is designed. At the same time, in order ...

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Abstract

This invention relates to the application method of frequency synthesis device in OFDM system, which is applied extensively in OFDM communication system, and it uses DDS combining with phase-locked loop to provide radio-frequency radical frequency for the frequency circuit in OFDM system. The frequency part directly in OFDM communication system adjusts carrier frequency deviation of the sender and collector. The advantage in this invention is that it has higher frequency differential rate, better phase noise character and wider frequency restricted portion and so on; it changes the output frequency rate of the frequency synthesis device to decrease the communication system carrier frequency deviation and lower the complexity of the synchronous algorithm of the base strip portion. The frequency synthesis device's trimming is obtained by changing DDS's frequency control character with microprocessor. This invention also designs elliptic low pass filter and low loop filter with fountain to provide better phase noise and frequency restricted portion character.

Description

technical field [0001] The invention is a frequency synthesizer that can be widely used in OFDM communication systems. The frequency synthesizer has extremely high frequency resolution and good phase noise characteristics, can adjust the carrier frequency deviation in the communication system according to the needs of customers, and reduce the complexity of the synchronization algorithm of the baseband part of the OFDM communication system. Background technique [0002] OFDM (Orthogonal Frequency Division Multiplexing) is a high-speed transmission technology in a wireless environment. As we all know, the frequency response curve of wireless channels is mostly non-flat, and the main purpose of OFDM technology is to divide a given channel into many orthogonal sub-channels in the frequency domain, use a sub-carrier for modulation on each sub-channel, and each sub-carrier is parallel transmission. In this way, although the overall channel is non-flat a...

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Application Information

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IPC IPC(8): H03L7/00H04L27/26
Inventor 刘进田玲蒋政波徐文虎严频频
Owner 南京东大宽带通信技术有限公司
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