Frequency synthesizer suitable for software radio system

A technology of frequency synthesizer and software radio, which is applied in the field of frequency synthesizer to achieve the effects of reducing ripple size, improving phase noise performance, and low gain

Inactive Publication Date: 2011-09-21
FUDAN UNIV
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  • Summary
  • Abstract
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Problems solved by technology

Both loops share a VCO

Method used

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  • Frequency synthesizer suitable for software radio system
  • Frequency synthesizer suitable for software radio system
  • Frequency synthesizer suitable for software radio system

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Embodiment Construction

[0033] The specific implementation manners provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0034] Figure 5 It is an overall structure diagram of a frequency synthesizer suitable for a software radio system according to the present invention. The system includes two loops, an automatic frequency calibration loop and a phase-locked loop. After the system is started, the first automatic frequency calibration loop works. At this time, the first switch SW1 is opened, the second switch SW2 and the third switch SW3 are closed; when the automatic frequency calibration process is completed, the first switch SW1 is closed and the second switch SW2 is closed. When the third switch SW3 is disconnected, the phase-locked loop starts to work. As can be seen from the figure, the switch is placed after the resistor R3 of the loop filter and before the capacitor C3. Due to the on-resistance R of the first switch SW1 on Figure ...

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Abstract

The invention belongs to the technical field of a radio frequency wireless transceiver and particularly relates to a frequency synthesizer suitable for a software radio system. The frequency synthesizer provided by the invention comprises module circuits such as a phase frequency discriminator (PFD), a charge pump, a loop filter, a voltage-controlled oscillator, a programmable frequency divider, a sigma-delta modulator, an automatic frequency calibration circuit, an orthogonal output frequency-halving divider and the like, can cover each frequency range of protocols such as WCDMA (wideband code division multiple access), GSM (global system for mobile communication), TD-SCDMA (time division-synchronization code division multiple access) and the like and is suitable for the software radio system. Compared with the traditional frequency synthesizer, the frequency synthesizer provided by the invention has the improvements in the aspects of voltage-controlled oscillator structure, loop design, automatic frequency calibration algorithm and the like to realize better phase noise and frequency spectrum stray performance and has short locking time.

Description

Technical field [0001] The invention belongs to the technical field of radio frequency wireless transceivers, and particularly relates to a frequency synthesizer suitable for software radio systems. Background technique [0002] At present, frequency synthesizers are widely used in the field of radio frequency technology and have become one of the indispensable modules of modern wireless communication systems. With the development of multi-mode reconfigurable wireless transceiver systems and the concept of software radio, the requirements for the performance of frequency synthesizers such as phase noise, lock time, spectrum spurs and output frequency range are getting higher and higher. [0003] Frequency synthesizers can generally be divided into two structures: integer frequency division and fractional frequency division. The frequency synthesizer of integer frequency division is relatively simple to implement, but the resolution of its output frequency must be an integer multip...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03L7/099H04B1/00H04B1/40
Inventor 潘姚华陈虎黄煜梅洪志良
Owner FUDAN UNIV
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