Method and device for improving radio frequency index of transmitter

Abstract

The invention relates to a method and apparatus for improving a radio frequency index of a transmitter. The apparatus comprises a baseband chip and a radio frequency chip. The baseband chip is used for arranging a radio frequency work frequency point. The radio frequency chip comprises a phase-locked loop and an interface and control logic. The phase-locked loop comprises a loop filter. The interface and control logic prestores multiple loop bandwidth configuration parameters, the loop bandwidth configuration parameters are respectively corresponding to different bandwidth, and the interface and control logic receives a working frequency point from the baseband chip, determines whether a current radio frequency working frequency point belongs to an interference frequency point, if so, configures the loop filter by use of the first loop bandwidth configuration parameter, and if not, configures the loop filter by use of the second loop bandwidth configuration parameter.

Description

technical field [0001] The invention relates to a GSM communication system, in particular to a method and a device for improving the radio frequency index of a transmitter. Background technique [0002] The modulation spectrum defined in the GSM specification is used to examine the out-of-band radiation characteristics of useful signals. According to the requirements of the specification, the spectral line power of the terminal at the transmission center frequency fc+ / -200kHz is less than -30dBc relative to the reference power at the carrier frequency; the spectral line power at fc+ / -400kHz is relative to The reference power ratio at the carrier frequency should be less than -60dBc, meeting this indicator has very high requirements for transmitter design. [0003] However, in most of the current GSM radio frequency transmitters, the modulation spectrum at the reference clock harmonic frequency + / - 200kHz has a worsening modulation spectrum than other frequency points. Caus...

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Problems solved by technology

[0006] However, the aforementioned solutions cannot improve the modulation spectrum problem caused by the reference clock harmonic interference caused by the RF chip itself.

And the current solution will add additional devices, such as adding filter elements (filter capacitors or magnetic beads) on the power pin of the chip, and sometimes need to add filter capacitors on the data lines and control lines

On the one hand, this increases the cost of the solution and increases the complexity of the system. On the other hand, adding additional circuits on the data line and control line will affect the integrity of the digital signal and introduce system risks.

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