KR100377915B1 - Apparatus for mixing frequency in a RF Transceiver - Google Patents

Abstract

The present invention relates to a frequency mixing device in an RF transceiver that improves (improves) the performance of an RF transceiver by eliminating unwanted (harmonic) signals. The present invention relates to two RF signals input through a divider. Signal, the intermodulation signal generator removes the carrier signal from the RF signal distributed by the splitter and outputs only the reverse phase intermodulation signal, and the variable phase shifter and attenuator change the amplitude and phase of the intermodulation signal, and delay The output unit delays and outputs the RF signal output from the splitter until the reverse phase intermodulation signal is generated, and the first synthesizer synthesizes and outputs the input RF signal and the reverse phase intermodulation signal output from the variable phase converter and the attenuator. . In addition, the combiner couples the local signal LO output from the local oscillator, the phase modulator shifts the phase of the combined local signal by 180 degrees, and the mixer combines the local signal and the RF signal output from the first synthesizer. To generate an intermediate frequency signal (IF signal), and the second synthesizer synthesizes the IF signal output from the mixer and the local signal output from the phase modulator to remove the phase-distorted signal from the mixer, and then outputs only the pure IF signal. do.

Description

Apparatus for mixing frequency in a RF Transceiver

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency mixer in an RF transceiver. In particular, an intermodulation signal generator and a local oscillation signal phase modulator are added to an input and an output terminal of a frequency mixer (mixer), thereby providing an unwanted wave (harmonic) signal. The present invention relates to a frequency mixer in an RF transceiver that is designed to eliminate (improv) the performance of an RF transceiver.

In general, when designing an RF transceiver of a mobile communication system (IMT-2000 system, PCS, DCS), a mixer (Mixer) is used for frequency conversion, which is a diode or a metal-semiconductor FET (MES FET). Since nonlinearity is used, a large number of unwanted harmonics and intermodulation distortion signals are generated when a LOCAL signal and an RF signal (or IF signal) are applied.

1 is a view showing the output of the mixer in the RF transceiver applied to the conventional mobile communication system of FIG. Here, reference numeral 10 denotes a mixer for mixing the input RF and the local signal LO to output an IF signal.

As shown, the third order intermodulation located within the band of intermodulation distortion signals when the carrier (RF signal frequency) is f1, f2, the local signal frequency is f _L , and the local signal frequency is greater than the RF signal frequency. Distortion signal component Because of the greatest effect, the distortion degree is judged a lot by the ratio of the fundamental frequency signal and the third-order intermodulation distortion signal level.

In order to improve this, conventionally, in the case of the passive mixer, the input signal is back-off or the harmonic balanced method is used to obtain the optimum operating conditions to eliminate the unwanted wave and intermodulation distortion signals. .

In the case of the active mixer, the unwanted wave and the intermodulation distortion signal were removed by using the method of obtaining the optimum operating voltage of the GaAs MES FET.

However, all of the known conventional methods cause the LO frequency signal level to be larger than the up or down frequency signal size, which causes another problem of local signal elimination, and has a limitation in attenuation characteristics of intermodulation distortion components. There was this.

All of these distortion components exist in the adjacent channel as interference or noise, thereby limiting the call quality of the entire communication system.

Therefore, the distortion signal is eliminated using dual or triple RF filters, but the intermodulation distortion signal close to the frequency band used and the local signal, which is a high-power signal, have the disadvantage of always degrading the call quality of the system due to the attenuation characteristic of the filter. Seemed.

Accordingly, the present invention has been proposed to solve various problems occurring in the frequency mixer when the conventional RF transceiver is implemented.

An object of the present invention is to improve the performance of an RF transceiver by adding an intermodulation signal generating unit and a local oscillating signal phase modulation unit to the input and output terminals of a frequency mixer (mixer), respectively, to eliminate unwanted (harmonic) signals. It is an object of the present invention to provide a frequency mixer in an RF transceiver.

Frequency mixing apparatus in the RF transceiver according to the present invention for achieving the above object,

In consideration of the distortion component to be produced in the frequency mixer (mixer), an inverse intermodulation signal generator having a reverse distortion characteristic is designed on the mixer input side to cancel the intermodulation distortion component, and the mixer output stage has the same power as the local signal. The local signal phase modulator is designed to have a magnitude and phase difference of 180 degrees, eliminating local signal components that are largely generated at the mixer output stage.

1 is a spectrum of an IF signal output from a mixer (mixer) in an RF transceiver applied to a conventional mobile communication system,

2 is a block diagram showing the configuration of a frequency mixing apparatus in an RF transceiver according to the present invention;

3 is a block diagram showing an embodiment of the intermodulation signal generator of FIG.

4A to 4F illustrate respective sub-input / output signal spectra of FIG. 2.

<Description of the symbols for the main parts of the drawings>

100 ..... Splitter

200 ..... intermodulation signal generator

300 ..... Variable Phase Shifters and Attenuators

400 ..... delay

500 ..... First Synthesizer

600 ..... Combiner

700 ..... Phase Modulator

800 ..... mixer

900 ..... Second Synthesizer

Hereinafter, described in detail with reference to the accompanying drawings, preferred embodiments of the present invention according to the technical spirit as described above.

2 is a block diagram showing the configuration of a frequency mixing apparatus in an RF transceiver according to the present invention.

Here, reference numeral 100 denotes a divider for distributing the input RF signal into two signals, and reference numeral 200 denotes an intermodulation signal generator for removing a carrier signal from the RF signal distributed by the divider 100 and outputting only an intermodulation signal. Reference numeral 300 denotes a variable phase converter and an attenuator for changing the amplitude and phase of the intermodulation signal output from the intermodulation signal generator 200.

In addition, reference numeral 400 denotes a delayer for delaying and outputting the RF signal output from the divider 100 until an inter-phase intermodulation signal is generated, and reference numeral 500 denotes an input RF output from the delayer 400. The first synthesizer synthesizes and outputs a signal and an intermodulation signal output from the variable phase converter and the attenuator 300.

Also, reference numeral 600 denotes a coupler for coupling a local signal LO output from a general local oscillator although not shown in the drawing, and reference numeral 700 denotes a 180-degree shift in phase of the local signal coupled from the combiner 600. A phase modulator indicates a mixer 800 that generates an intermediate frequency signal (IF signal) by mixing the local signal and the RF signal output from the first synthesizer 500.

In addition, the reference numeral 900 is a second to output the pure IF signal only after removing the phase-distorted signal from the mixer 800 by combining the IF signal output from the mixer 800 and the local signal output from the phase modulator 700 The synthesizer is shown.

The operation of the frequency mixing apparatus in the RF transceiver according to the present invention configured as described above will be described in detail with reference to FIGS. 3 and 4.

First, the divider 100 of FIG. 2 divides the carrier signals RF having the frequencies f1 and f2 as shown in FIG. 4a into two RF signals and outputs them through two paths, respectively. One RF signal to be output is input to the delay unit 400, and another RF signal is input to the intermodulation signal generator 200.

The intermodulation signal generator 200 removes a carrier signal from an input RF signal and outputs only the intermodulation signal.

3 is a diagram illustrating an embodiment of the intermodulation signal generator 200.

Here, reference numeral 210 denotes a divider for distributing and outputting the input RF signal (Pin) into two RF signals, and 220 denotes an amplifier for amplifying and outputting only the intermodulated signal from the signal output from the divider 210 (MMIC amplifier). Reference numeral 230 denotes a variable attenuator for attenuating the magnitude of the intermodulation signal output from the amplifier 220, and reference numeral 240 denotes a phase shifter for converting a phase of the RF signal output from the divider 210. Reference numeral 250 denotes a synthesizer for synthesizing the output signal of the variable attenuator 230 and the output signal of the phase shifter 240 to output only an intermodulation signal.

The intermodulation signal generator 200 configured as described above first divides the RF signal input from the divider 210 and outputs each of the two paths, and the amplifier 220 transmits one of the two paths. Only the intermodulated signal is amplified and output from the RF signal.

In addition, the variable attenuator 230 changes the magnitude of the intermodulated signal output from the amplifier 220. That is, the magnitude of the intermodulation signal output from the amplifier 220 is attenuated according to the variable attenuation level.

The scaled intermodulation signal is input to the synthesizer 250.

Next, the phase converter 240 converts the phase of the RF signal output from the divider 210 and transmits the phase to the synthesizer 250.

The synthesizer 250 synthesizes the signal output from the variable attenuator 230 and the signal output from the phase shifter 240, so that only the intermodulation signal having the spectrum as shown in FIG. 4B is available in the variable phase shifter and the attenuator 300. To pass on.

That is, the intermodulation signal generator 200 cancels each other by adjusting the carrier signals of f1 and f2 among the signals output from the variable attenuator 230 and the phase shifter 240 to have the same power and mutually reverse phase. Only modulated signal is output.

Next, the variable phase shifter and attenuator 300 converts the amplitude and phase of the intermodulation signal input to the set phase shift level and the attenuation level.

The intermodulation signal obtained by converting amplitude and phase is applied to the first synthesizer 500.

In addition, the delay unit 400 delays the RF signal output from the distributor 100 by the operation time of the intermodulation signal generator 200, the variable phase shifter and the attenuator 300, and then delays the RF signal to the first synthesizer 500. To pass.

The first synthesizer 500 synthesizes and outputs two input signals, that is, an RF signal output from the delay unit 400 and an intermodulation signal output from the variable phase converter and the attenuator 300.

4C illustrates a spectrum of an RF signal output from the first synthesizer 500.

Meanwhile, the local signal output from the local oscillator used to down-convert the RF signal input in the general mobile communication system to the IF signal is a signal as shown in FIG. 4D, and the mixer 800 is similar to the local signal as shown in FIG. 4D. The RF signal as shown in FIG. 4C is mixed to output an IF signal as shown in FIG. 4E.

Referring to FIG. 4E, the mixer 800 mixes a carrier wave, which is one of input signals, and a local signal, and generates intermodulation distortion frequency components.

In this case, since the intermodulation inverse distortion signal passing through the intermodulation signal generator 200 and the variable phase shifter and the attenuator 300 is mixed with the local signal, the intermodulation distortion frequency components generated during the frequency mixing are the variable phase shifter and the attenuator 300. Cancels by canceling the intermodulation inverse distortion signal output from

This removes the distorted frequency components that occur when the mixer 800 mixes the local and RF signals.

Meanwhile, the combiner 600 combines the local signals flowing into the mixer 800, and the phase modulator 700 shifts the phase of the local signal coupled by the combiner 600 by 180 degrees.

When the local signal shifted 180 degrees in phase and the IF signal output from the mixer 800 are synthesized by the second synthesizer 900, the high power local signal component output from the mixer 800 is canceled to be canceled by FIG. 4F. Shows the same spectrum.

That is, the high power local signal component output from the mixer 800 may be removed.

According to the present invention "frequency mixing apparatus in the RF transceiver" described above, there is an advantage that can be minimized the large power harmonics (harmonics) generated by the intermodulation distortion signal by the mixer and the local oscillator.

In addition, by eliminating the intermodulation distortion signal and the large power harmonics (harmonics), the degradation of the call quality can be prevented in advance, thereby improving the performance of the RF transceiver.

In addition, since the frequency mixer can remove intermodulation distortion signals and large power disturbances on its own, it is possible to eliminate the multiple filters that are necessary for the existing frequency mixers, thereby reducing the cost of production. It can be lowered, which has the effect of promoting economic benefits.

Claims (3)

Splitter for distributing RF signal into two signals, Intermodulation signal generator for removing carrier signal from RF signal distributed in the splitter and outputting only intermodulation signal, Amplitude and phase of intermodulation signal output from the intermodulation signal generator In the RF transceiver comprising a variable phase converter and an attenuator, a retarder, a first synthesizer, a combiner, a phase modulator, a mixer, a second synthesizer to change the frequency of the RF signal down to an IF signal, The intermodulation signal generator, A divider 210 for dividing and outputting the input RF signal into two RF signals, an amplifier 220 (MMIC amplifier) for amplifying and outputting only an intermodulated signal from the signal output from the divider 210; A variable attenuator 230 for attenuating the magnitude of the intermodulated signal output from the amplifier 220, a phase converter 240 for converting a phase of the RF signal output from the divider 210, and the variable attenuator ( And a synthesizer (250) for synthesizing an output signal of the phase shifter (240) and the output signal of the phase shifter (240) and outputting only an intermodulated signal. delete delete