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Frequency shift circuit and frequency shift method

A frequency shift, digital circuit technology, applied in the field of frequency shift of demodulators, can solve the problems of increased power consumption, inability to realize, no public circuit, etc., and achieve the effect of reducing power consumption

Inactive Publication Date: 2007-01-31
LENOVO INNOVATIONS LTD HONG KONG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] However, in the above prior art, a ROM and a multiplexer for frequency shift are required, and no effective way is disclosed for avoiding a complicated circuit, an increase in circuit size, and an increase in power consumption
Cannot realize multi-carrier receiver with small circuit size and energy saving

Method used

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  • Frequency shift circuit and frequency shift method
  • Frequency shift circuit and frequency shift method
  • Frequency shift circuit and frequency shift method

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Embodiment Construction

[0049] Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

[0050] A frequency-shift demodulation circuit according to the present invention includes a known quadrature frequency converter (not shown), which reproduces an in-phase (I) component and a quadrature (Q) component from a received signal according to a quadrature demodulation scheme .

[0051] Here, if Figure 10 As shown, the I and Q components are reproduced from the signal received on the center carrier and two subcarriers. The frequencies of the subcarriers are shifted from the center carrier frequency by the same amount at the lower and upper frequencies, respectively. In this example, the frequency offset of each subcarrier is 1.25MHz, and the chip rate is 1.2288Mcps. As previously described, since the number of carriers is 3, a maximum data rate of 43.3 kbps can be obtained.

[0052] like figure 1 As shown, the frequency shift demodu...

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Abstract

A frequency shifting circuit suitable for a digital demodulator in a multi-carrier communications system is disclosed. After converting analog signal vectors (I, Q) to the input signal vectors according to a predetermined sampling clock, control data (D-1, D0, D1, ... D11) is generated from a frequency difference between sub-carrier bands and center carrier band. A signal vector rotator (102, 104) is provided corresponding to each of the sub-carrier bands and rotates the input signal vectors on the I-Q plane by an angle determined depending on corresponding control data to shift the sub-carrier bands of the input signal vectors to the center carrier band. A band-pass filter passes an output signal vector of the center carrier band.

Description

technical field [0001] The present invention relates to frequency shifting techniques suitable for demodulators of receivers used in multi-carrier communication systems. Background technique [0002] In the future mobile communication system, a lot of attention is focused on the IMT-2000 (International Mobile Telecommunication-2000) system defined by ITU-R TG8 / 1. Several systems have been proposed, such as W-CDMA (Wideband-Code Division Multiple Access) and CDMA2000, which can employ a multi-carrier scheme to allow high-speed data transmission. [0003] The CDMA 2000 system is designed to be upwardly compatible with CDMAOne conforming to IS-95, and adopts a multi-carrier scheme in downlink transmission. An example of a multi-carrier scheme in a CDMA communication system is shown in Figure 10 middle. In this example, the frequency offset of the subcarriers (carrier-1 and carrier+1) from the center carrier is set to be 1.25MHz, and the chip rate is 1.2288Mcps (megacharacter...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04J9/00H04L27/38H04B1/707H04J1/00H04J11/00H04J13/00H04L27/22H04L27/26
CPCH04L27/2657H04L27/2679
Inventor 市原正贵
Owner LENOVO INNOVATIONS LTD HONG KONG