KR100622337B1 - Method for reducing EVM using phase control, and Transmitter using it in a EDGE - Google Patents

Abstract

The present invention relates to a mobile communication system (hereinafter, referred to as an 'EDGE system') that performs high-speed data transmission. More specifically, the present invention relates to a method for reducing the minimum EVM using AM and PM LOOP phase control and a transmitter to which the same is applied. will be.

The apparatus according to the present invention includes a baseband circuit section for generating an I / Q signal, a modulator for modulating the I / Q signal into a predetermined signal at an intermediate frequency, and a signal detector for detecting PM and AM signals from the modulator output. And a phase filter unit for passing only a predetermined band of the detected PM signal, and an amplitude filter unit for passing only a predetermined band of the detected AM signal, wherein the baseband circuit unit includes the phase filter unit and the amplitude filter. It receives a negative output, characterized in that to adjust the AM and PM phase according to a predetermined algorithm.

Polar Loop, EDGE, EVM Error

Description

Method for reducing EVM using phase control, and transmitter using it in a EDGE in a mobile communication system performing high-speed data transmission             

1 is a view showing the configuration of a transmitting end of the EDGE system according to the prior art,

2 shows an example of an EVM error,

3 is a diagram illustrating a configuration of a transmitting end of an EDGE system according to an embodiment of the present invention;

4 is a flowchart illustrating a phase control method for EVM reduction according to an embodiment of the present invention;

5A and 5B are diagrams showing waveforms of signals at positions ① and 3 of FIG. 3.

The present invention relates to a mobile communication system (hereinafter, referred to as an 'EDGE system') that performs high-speed data transmission. Specifically, the present invention relates to a method for reducing the minimum EVM using AM and PM LOOP phase control and to a transmitter using the same. It is about.

The EDGE (Enhanced Data for GSM Evolution) system is implemented to provide a high data rate (2Mbps) in GSM (TDMA).

1 is a view showing the configuration of a transmitting end of the EDGE system according to the prior art.

The transmitting stage of the EDGE system includes a base band circuit (not shown) for generating an I / Q signal according to transmission data, and a PM (Phase Modulatin, for generating an RF signal using the I / Q signal). Phase Modulation) / AM (Amplitude Modulation) loop (Polar Loop) and a power amplifier for amplifying the generated RF signal and transmits to the antenna stage.

Referring to FIG. 1, a configuration of a polar loop circuit and a power amplifier stage is described. The I / Q modulator 100 receives an I / Q signal from a miracle band circuit unit (not shown) and performs I / Q modulation. The PM signal is detected by the PM / AM detector 110 and input to the TXVCO 140 through the phase filter 120. In the case of an AM signal, it is detected by the PM / AM detector 110 and input as an amplitude control signal of the amplification module 150 via the amplitude filter 130.

Here, the output signal of the amplification module 150 is coupled by a coupler (not shown) and input to the PM / AM detector 110 through a feedback / down converter 160 for output power correction. The feedback / down converter 160 down-converts the RF output signal coupled with the signal input from the RF VCO to a mixed or intermediate frequency and inputs the signal to the PM / AM detector 110.

The EDGE transmitter according to the related art has a problem in that a signal path from the phase filter unit 120 to the amplification module 150 and the amplitude filter unit 130 to the amplification module 150 is physically long or short in FIG. 1. If the displayed signal path is long or short, the amplification module 150 causes an error vector magnitude (EVM) error when the AM and PM signals are combined. In particular, since the AM signal path often forms a relatively long loop, there is a frequent delay in the circuit. If such a delay occurs, the PM signal and the AM signal cannot be combined at the correct position, which causes a problem that the EVM error becomes large. 2 is a diagram illustrating an example of such an EVM error.

It is therefore an object of the present invention to provide a method and apparatus for solving the above problems of the prior art.

A specific object of the present invention is to minimize the EVM error through phase control of the AM / PM loop.

Apparatus according to the present invention for achieving the above object

A transmitter for reducing EVM error in a mobile communication system performing high speed data transmission,

A baseband circuit section for generating an I / Q signal, a modulator for modulating the I / Q signal into a predetermined signal at an intermediate frequency, a signal detector for detecting PM and AM signals from the modulator output, and the detected PM And a phase filter unit for passing only a predetermined band of a signal, and an amplitude filter unit for passing only a predetermined band of the detected AM signal, wherein the baseband circuit unit receives an output of the phase filter unit and the amplitude filter unit, The AM and PM phases are adjusted according to a predetermined algorithm.

The method according to the present invention for achieving the above object is

A baseband circuit section for generating an I / Q signal, a modulator for modulating the I / Q signal into a predetermined signal at an intermediate frequency, a signal detector for detecting PM and AM signals from the modulator output, and the detected PM A method for reducing an EVM error in a transmitter for high speed data transmission comprising a phase filter unit for passing only a predetermined band of a signal and an amplitude filter unit for passing only a predetermined band of the detected AM signal,

Feeding back AM and PM signals from the phase filter unit and the amplitude filter unit to the baseband circuit unit, measuring an initial EVM value from the feedback signal, and adjusting the phase of the AM or PM signal for a predetermined time period. Randomly changing, re-measuring an EVM value using the randomly changed AM or PM signal, and comparing the smallest value of the original EVM value and the re-measured EVM value to determine an AM and PM signal. Controlling the phase.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The principle of EVM error minimization according to the present invention is to minimize the EVM error by inputting the phases of the AM and / or PM loops to the baseband circuit part and adjusting the phases as desired.

3 is a diagram illustrating a configuration of a transmitting end of an EDGE system according to an embodiment of the present invention.

Referring to FIG. 2, the transmitting end includes a baseband circuit part (BB circuit part) 300 for generating an I / Q signal, an I / Q modulator 310 for modulating the I / Q signal into a predetermined signal having an intermediate frequency, and the I A PM / AM signal detector 320 for detecting PM and AM signals from the output of the / Q modulator 310, a phase filter 330 for passing only a predetermined band of the detected PM signal, and limiting the detected AM signal to a predetermined level And an amplitude filter unit 340 to pass through.

In the present invention, the output of the phase filter unit 330 and the output of the amplitude filter unit 340 are fed back to the input terminal of the baseband circuit unit 300. The baseband circuit unit 300 adjusts the phase of the AM and PM signals by software, so that the phase-adjusted AM signal is input to the AM control signal of the power amplifier module 360, and the phase-adjusted PM signal is a transmission voltage controlled oscillator (TXVCO). ) Is entered.

Hereinafter, phase control for reducing EVM errors in the baseband circuit unit will be described.

4 is a flowchart illustrating a phase control method for EVM reduction according to an embodiment of the present invention.

First, in step S410, the EVM value is measured using AM and PM signals fed back from the phase filter unit and the amplitude filter unit. In operation S420, the measured initial EVM value is recorded in a predetermined memory. Next, in step S430, the AM and PM signals are randomly changed, and the EVM is measured again. Thereafter, in step S440, the first EVM value stored in the memory is compared with the re-measured EVM value. If the absolute value of the remeasured EVM value is greater than the first measured EVM value, the comparison returns to step S430 to give the phase change again to remeasure the EVM value. As a result, the smallest EVM value can be found by comparing the remeasured EVM value with the randomly changed AM and PM signals and the first measured EVM value. The baseband circuit unit 300 outputs an AM or PM signal having the smallest EVM value to the transmission voltage control detector and the power amplifier module 360 through an output terminal.

FIG. 5A is a PM signal whose phase is + and − controlled by the baseband circuit portion, and illustrates an output signal (1 of FIG. 3) of the baseband circuit portion. 5B is an AM signal whose phase is controlled by the baseband circuit portion, and shows an output signal (2 in FIG. 3) of the baseband circuit portion.

While the invention has been described above based on the preferred embodiments thereof, these embodiments are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention should be construed to include not only the appended claims but also all of the above changes, modifications or adjustments.

As described above, since the present invention enables phase control of AM or PM signals while measuring EVM, there is an advantage in that phase control can be performed so that the minimum EVM is achieved by continuously tracking the EVM value.

Claims (4)

A transmitter for reducing EVM error in a mobile communication system performing high speed data transmission, A baseband circuit section for generating an I / Q signal, a modulator for modulating the I / Q signal into a predetermined signal at an intermediate frequency, a signal detector for detecting PM and AM signals from the modulator output, and the detected PM A phase filter unit for passing only a predetermined band of the signal and an amplitude filter unit for passing only a predetermined band of the detected AM signal, And the baseband circuit part receives the output of the phase filter part and the amplitude filter part, and adjusts AM and PM phases according to a predetermined algorithm. The method of claim 1, wherein the algorithm is The first measured EVM is stored in a predetermined memory, the phase of the AM or PM signal is randomly changed, the EVM is measured and compared with the value stored in the memory, and the AM and PM signals are adjusted to satisfy the minimum EVM. Transmitter. The method of claim 1 or 2, wherein the baseband circuit portion And outputting the phase-adjusted AM signal as a control signal of the power amplification module and outputting the phase-adjusted PM signal to a transmission voltage controlled oscillator. A baseband circuit section for generating an I / Q signal, a modulator for modulating the I / Q signal into a predetermined signal at an intermediate frequency, a signal detector for detecting PM and AM signals from the modulator output, and the detected PM A method for reducing an EVM error in a transmitter for high speed data transmission comprising a phase filter unit for passing only a predetermined band of a signal and an amplitude filter unit for passing only a predetermined band of the detected AM signal, Feeding back AM and PM signals from the phase filter unit and the amplitude filter unit to the baseband circuit unit; Measuring an initial EVM value from the feedback signal; Randomly changing the phase of an AM or PM signal for a predetermined time period; Re-measuring an EVM value using the randomly changed AM or PM signal; Comparing the initial EVM value with the re-measured EVM value to control phases of AM and PM signals.

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