KR20020049072A - A Wireless Transmitter for Decreasing Harmonic Distortion - Google Patents

Abstract

PURPOSE: A wireless transmitter for decreasing the distortion of a harmonic frequency is provided to decrease the distortion of the harmonic frequency at a low cost by adding N digital-analog converters and an adder. CONSTITUTION: N digital-analog converters(101-10N) receive digital signals and converts the received digital signals into analog signals having inter-different spurious frequency characteristics. An adder(110) adds the converted analog signals. An IF(Intermediate Frequency) converting unit(200) converts the analog signal added through the adder(110) into an IF. An RF(Radio Frequency) converting unit(300) converts the converted IF into an RF and transmits the RF.

Description

A Wireless Transmitter for Decreasing Harmonic Distortion

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless transmitters, in particular, to reducing harmonic distortion for reducing distortion in harmonics due to spurious signals caused by the characteristics of a digital-to-analog converter.

The conventional wireless transmitter converts a digital signal into an analog signal by using a single digital-to-analog converter, and the Spurious-Free Dynamic Range (SFDR), which is a measure of harmonic distortion of the wireless transmitter, is a digital-to-analog converter. Depends on the characteristics.

1 is a block diagram showing the structure of a conventional radio transmitter.

Referring to FIG. 1, a digital-to-analog converter 100 for converting a digital signal to be transmitted to analog, an intermediate frequency converter 200 for converting the converted analog signal to an intermediate frequency, and the intermediate frequency converter 200 It is configured to include a radio frequency conversion unit 300 for converting the intermediate frequency converted into a radio frequency and a radio frequency converted by the radio frequency conversion unit 300 in the).

On the other hand, the intermediate frequency converter 200 outputs an intermediate frequency signal by mixing the intermediate frequency local oscillator 202 for outputting the intermediate frequency and the analog signal changed from the intermediate frequency and the digital-analog converter 100. It comprises an intermediate frequency mixer 201 and the intermediate frequency signal filter 203 for filtering the intermediate frequency mixed in the intermediate frequency mixer 201 in the intermediate frequency signal.

On the other hand, the radio frequency converter 300 is a radio frequency local oscillator 302 for outputting a radio frequency and the radio frequency and the intermediate frequency converted from the intermediate frequency conversion unit 200 by mixing the radio frequency signal output It comprises a radio frequency mixer 301 and a radio frequency signal filter 303 for filtering out the radio frequency mixed by the radio frequency mixer 301 in the radio frequency signal.

Referring to the operation of the conventional wireless transmitter device configured as described above, if the digital signal to be transmitted through an analog-to-analog converter 100 to convert the digital signal, the digital signal is converted into an analog signal and corresponds to harmonic distortion. A spurious signal is generated.

The analog signal converted as described above is converted into an intermediate frequency through the intermediate frequency converter 200, and the intermediate frequency mixer 201 mixes the analog signal and the intermediate frequency signal output from the intermediate frequency local oscillator 202 in the intermediate frequency mixer 201. The frequency signal is output.

Here, if the mixed intermediate frequency of the intermediate frequency signal is filtered using the intermediate frequency filter 203, the original signal converted to the intermediate frequency is output.

The intermediate frequency converted as described above is converted into a radio frequency again. The conversion to the radio frequency is performed via the radio frequency conversion unit 300. First, the converted intermediate frequency and the radio frequency signal output from the radio frequency local oscillator 302 are mixed in the radio frequency mixer 301. By outputting a radio frequency signal, and by filtering out the mixed radio frequency of the output radio frequency signal using the radio frequency filter 303, the original signal converted to radio frequency is output.

The output radio frequency is transmitted to the air through the antenna.

However, conventionally there was only one digital-to-analog converter, and the spurious signal, which is a measure of the distortion of the radio transmitter, is affected by the frequency characteristic of the digital-to-analog converter, so that the distortion could be large, and a high performance digital-analog to reduce the distortion If you use a converter, there was an inconvenience in manufacturing and cost.

In order to solve the above problem, the present invention adds N digital-to-analog converters having different spurious frequency characteristics and an adder that adds a signal from each digital-to-analog converter so that N digital-to-analog converters are connected to the same input signal. The original signal shows the same output, but the spurious signal has different output characteristics, and when these signals are added, the original signal becomes larger and the spurious signal decreases, thereby reducing harmonic distortion at low cost. It is an object of the present invention to provide a wireless transmitter device for reducing.

1 is a block diagram showing the structure of a conventional radio transmitter.

2 is a block diagram illustrating a structure of a wireless transmitter for reducing harmonic distortion according to an embodiment of the present invention.

<Description of Main Parts of Drawing>

100, 101 ~ 10N: Digital to Analog Converter 110: Adder

201: intermediate frequency mixer 202: intermediate frequency local oscillator

203: intermediate frequency signal filter 301: radio frequency mixer

302: radio frequency local oscillator 303: wireless transmission signal filter

400: antenna

Wireless transmitter for reducing harmonic distortion according to the present invention,

N digital-to-analog converters each receiving a digital signal and converting the digital signal into an analog signal having different spurious frequency characteristics;

An adder for adding and outputting the converted analog signals;

An intermediate frequency converting unit converting the analog signal summed through the adder into an intermediate frequency;

And a radio frequency converter for converting the converted intermediate frequency into a radio frequency and transmitting the radio frequency.

Preferably, the adder is characterized in that the correlated signal is made large, and the correlated signal is made small.

When described in detail with reference to the accompanying drawings, a wireless transmitter for reducing harmonic distortion according to the present invention as follows.

2 is a block diagram illustrating a structure of a wireless transmitter for reducing harmonic distortion according to an exemplary embodiment of the present invention.

2, an intermediate frequency converter 200 and an intermediate frequency converter 200 for converting an analog signal converted by the digital-analog converter 500 and the digital-analog converter 400 into an intermediate frequency It is configured to include a radio frequency conversion unit 300 for converting the intermediate frequency converted into a radio frequency and a radio frequency converted by the radio frequency conversion unit 300 in the air (400).

Meanwhile, the digital-analog converter 500 adds analog signals converted from the N digital-analog converters 500 to 50n and the N digital-analog converters 501 to 50N having different spurious frequency characteristics. The adder 510 is configured.

On the other hand, the intermediate frequency converter 200 outputs an intermediate frequency signal by mixing the intermediate frequency local oscillator 202 for outputting the intermediate frequency and the analog signal changed from the intermediate frequency and the digital-analog converter 100. It comprises an intermediate frequency mixer 201 and the intermediate frequency signal filter 203 for filtering the intermediate frequency mixed in the intermediate frequency mixer 201 in the intermediate frequency signal.

On the other hand, the radio frequency converter 300 is a radio frequency local oscillator 302 for outputting a radio frequency and the radio frequency and the intermediate frequency converted from the intermediate frequency conversion unit 200 by mixing the radio frequency signal output It comprises a radio frequency mixer 301 and a radio frequency signal filter 303 for filtering out the radio frequency mixed by the radio frequency mixer 301 in the radio frequency signal.

Referring to the operation of the radio transmitter for reducing the harmonic distortion according to the present invention configured as described above are as follows.

When a digital signal for transmitting a radio signal is generated, the digital signal is transmitted to N digital-to-analog converters 501 to 50N having different spurious frequency characteristics. Since the N digital-analog converters have different spurious frequency characteristics, the output characteristics are the same for the same input signal, but the spurious signals are different in the N digital-analog converters 501 to 50N.

That is, the waveform diagrams (a) and (b) in FIG. 2 are output signals from the digital-to-analog converters 1,2 (501,502) having different spurious frequency characteristics, respectively, but the original signal shows the same output but the spurious signal. The characteristics of come out differently.

When the signals from the N digital-to-analog converters 501 to 50N having different spurious characteristics are added using the adder 510, the original signals are added, as in waveform (c) of FIG. The larger, the different spurious signals become smaller. That is, the larger the number of the N digital-to-analog converters 501 to 50N, the larger the original signal and the smaller the spurious signal, thereby reducing distortion. This is because the adder 510 has a property of making the correlated signal large and the uncorrelated signal small.

The analog signal with the least distortion is mixed in the intermediate frequency output from the intermediate frequency local oscillator 202 and the intermediate frequency mixer 201 and converted to the intermediate frequency signal through the intermediate frequency signal filter 203.

The converted intermediate frequency signal is mixed with the radio frequency output from the radio frequency signal local oscillator 302 and the radio frequency mixer 301 and converted into a radio frequency signal through the radio frequency signal filter 303.

The converted radio frequency is output to the air through an antenna and transmitted.

As described above, the wireless transmitter for reducing harmonic distortion includes a digital-analog converter having spurious frequency characteristics different from harmonic distortion caused by a spurious signal generated by a conventional wireless transmitter using one digital-analog converter. By using N to analogize and add using an adder, the original signal having the same content becomes larger and the spurious signal having different output characteristics becomes smaller, thereby reducing harmonic distortion at a low cost.

Claims (2)

N digital-to-analog converters each receiving a digital signal and converting the digital signal into an analog signal having different spurious frequency characteristics; An adder for adding and outputting the converted analog signals; An intermediate frequency converting unit converting the analog signal summed through the adder into an intermediate frequency; And a radio frequency converter for converting the converted intermediate frequency into a radio frequency and transmitting the radio frequency. 2. The radio transmitter of claim 1, wherein the adder has a characteristic of making the correlated signal large and the uncorrelated signal small.