KR0150143B1 - If frequency generating circuit in radio communication system - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

An intermediate frequency generating circuit of a wireless communication system.

2. The technical problem to be solved by the invention

The present invention generates a pure intermediate frequency after mixing the radio frequency signal and the local signal to remove the spurious components generated when the conversion to the intermediate frequency.

3. Summary of Solution to Invention

A wireless amplifier for amplifying the radio frequency signal received from the antenna: dividing the power level of the amplified radio frequency signal by the amplification means by 1/2 and the phase does not change with the first radio frequency signal shifted phase by 90 degrees A power divider for converting a second wireless frequency signal into a second wireless frequency signal; and a frequency multiplier for multiplying a frequency of the first wireless frequency signal to output a third wireless frequency signal: a power reduction amount of the power level of the third wireless frequency signal And a power control attenuator reducing the output signal as a fourth radio frequency signal, and outputting the fourth radio frequency signal. The first bandpass filter transmits only the second harmonic included in the fourth radio frequency signal and outputs the fifth radio frequency signal. A phase adjuster for changing a phase of a radio frequency signal according to a phase shift value and outputting the sixth radio frequency signal; a local oscillator for generating a local signal; and the second radio frequency signal and a local part. A mixer for generating a first intermediate frequency signal by mixing an arc; and a second band pass filter for removing a harmonic component included in the first intermediate frequency signal and generating a second intermediate frequency signal. The phase of the radio frequency signal is shifted by 90 °, and the intermediate frequency signal is mixed to form a power mixer that generates an intermediate frequency.

4. Important uses of the invention

Used to generate intermediate frequency of wireless communication system.

Description

Intermediate Frequency Generation Circuit of Wireless Communication System

1 is a block diagram showing an intermediate frequency generation circuit of a conventional wireless communication system.

2 is a block diagram showing an intermediate frequency generation circuit of a wireless communication system according to the present invention.

* Explanation of symbols for main parts of the drawings

10: RF stage 20: Mixer

30: local oscillator 40: second band pass filter

50: power divider 60: frequency multiplier

70: power control attenuator 80: first band pass filter

90: phase adjuster 100: power mixer

The present invention relates to an intermediate frequency generating circuit of a wireless communication system, and more particularly, to an intermediate frequency generating circuit that generates a pure intermediate frequency after removing a spurious component generated by converting a radio frequency signal and a local signal into an intermediate frequency.

In general, a signal transmitted from a wireless communication system is expressed as a current or voltage that changes with time as a means for transmitting information. This information signal itself is inadequate for transmission to a communication system. That is, since most information signals are low frequency signals in the Khz band, the size of the antenna becomes very inefficient. Because the size of the antenna is related to the wavelength. For example, if the frequency is f, the wavelength is λ, and the velocity of the electromagnetic wave is v, the relationship between them is as shown in Equation 1 below.

fλ = v ............. (1)

Here, the speed v of the electromagnetic wave is the speed of light, and if the frequency of the information signal is in the Khz band, the wavelength λ becomes lambda = (3.0 × 10 ⁸ (m / s)) / 1000 (HZ) = 300 km. Therefore, an antenna having a wavelength of 300 km must be installed, but a signal having a short wavelength is required because it is not practical. Therefore, the low frequency information signal is generated using the characteristics of the high frequency signal (carrier) (frequency, phase, amplitude). This process of changing one signal by another is called modulation and is performed at the transmitter. The receiver must recover the original information signal. This process is called demodulation. Demodulation involves converting a received radio frequency signal into an intermediate frequency. The conversion to the intermediate frequency is made by a mixer that mixes radio frequency signals and local signals. Such mixers include an Image Rejection Mixer and a Double Balanced Mixer.

1 is a block diagram showing an intermediate frequency generating circuit for generating an intermediate frequency using a double balance mixer of a conventional wireless communication system.

Referring to FIG. 1, the radio frequency signal received through the antenna ANT is amplified by the RF stage 10 and then applied to the double balance mixer 20. The dual balance mixer 20 inputs and mixes the radio frequency signal amplified by the RF stage 10 and the local signal generated by the local oscillator 30 and then generates an intermediate frequency. The intermediate frequency is expressed as a component of the sum and difference of the local signal and the radio frequency signal amplified by the RF terminal 10. That is, when the intermediate frequency is IF, the local signal is LO, and the radio frequency signal is RF, their relationship is as shown in Equation 2 below.

IF = mRF + nLO .............. (2)

Here m and n represent natural numbers.

The band pass filter 40 generates a signal in which the intermediate frequency thus generated is filtered by a predetermined band. The output of the bandpass filter 40 is applied to an IF stage (not shown) for amplifying it.

However, when the characteristics of the band pass filter 40 are poor and the selection of the radio frequency signal and the local signal is not appropriate, twice the local frequency and the local signal are mixed to approach the intermediate frequency. This causes a problem that worsens the spurious component in the use band of the intermediate frequency, which degrades the performance of the system.

Accordingly, an object of the present invention is to provide an intermediate frequency generating circuit that generates a pure intermediate frequency after removing a spurious component generated by converting a radio frequency signal and a local signal into an intermediate frequency.

According to an aspect of the present invention, there is provided a wireless amplifier for amplifying a radio frequency signal received from an antenna. The power level of the radio frequency signal amplified by the wireless amplification means is divided by 1/2 and the phase is 90. A power divider for converting the transitioned first radio frequency signal to a second radio frequency signal of which phase is not changed, and a frequency multiplier for multiplying the frequency of the first radio frequency signal to output a third radio frequency signal; A power control attenuator for reducing the power level of the third radio frequency signal by the amount of power attenuation and outputting it as a fourth radio frequency signal. A first band pass filter, a phase adjuster for changing a phase of the fifth radio frequency signal according to a phase shift value and outputting the sixth radio frequency signal, and a local oscillator for generating a local signal, and the second radio frequency signal. A mixer for inputting and mixing a signal and a local signal and generating a first intermediate frequency signal: removing a harmonic component included in the first intermediate frequency signal and generating a second intermediate frequency signal Second band-pass filter with: a phase of the sixth radio frequency signal 90 Transition by as much as possible, characterized in that consisting of a power mixer for generating the intermediate frequency by mixing the intermediate frequency signal.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if they appear in different drawing words. In addition, in the following description, many specific details such as components of specific circuits are shown, which are provided to help a more general understanding of the present invention, and the present invention may be practiced without these specific details. It will be obvious to those skilled in the art. And in describing the present invention, if it is determined that the detailed description of the related known function or configuration may obscure the subject matter of the present invention, the detailed description thereof will be omitted.

2 is a block diagram showing an intermediate frequency generating circuit for generating an intermediate frequency using a double balance mixer in a wireless communication system according to the present invention.

Referring to FIG. 2, an RF stage 10 for amplifying a radio frequency signal received from an antenna ANT and a power level of a radio frequency signal amplified by the RF stage 10 are divided by 1/2 and 90 phase A power divider 50 for converting the transitioned first radio frequency signal to a second radio frequency signal unchanged in phase, and a frequency multiplier for multiplying the frequency of the first radio frequency signal and outputting the result as a third radio frequency signal. 60, a power control attenuator 70 that reduces the power level of the third radio frequency signal by the amount of power attenuation and outputs the fourth radio frequency signal, and only the second harmonics included in the fourth radio frequency signal. A first band pass filter 80 which passes through and outputs the fifth radio frequency signal, and a phase adjuster 90 which changes the phase of the fifth radio frequency signal according to a phase shift value and outputs the sixth radio frequency signal; And a local oscillator 30 for generating a local signal, a hop combiner 20 for inputting and mixing the second radio frequency signal and a local signal, and generating a first intermediate frequency signal, and the first intermediate frequency signal. Remove the harmonic content included in the second intermediate frequency And a second bandpass filter (40) for generating a number, a phase of the sixth radio frequency signal 90 It consists of a power mixer 100 that transitions by and generates an intermediate frequency IF by mixing the intermediate frequency signals.

The operation of the intermediate frequency generating circuit having the above configuration is as follows.

Before explaining the operation, let the radio frequency signal be 2 Acosωt. Here 2A represents the power level of the radio frequency signal and ω represents the phase.

The radio frequency signal 2Acosωt received from the antenna ANT is amplified by the RF terminal 10 and then input to the power divider 50. The power divider 50 divides the power level of the radio frequency signal 2Acosωt amplified by the RF terminal 10 by 1/2 and shifts the phase by 90 ° to phase with the first radio frequency signal Acos (ωt-90 °). This unchanged second radio frequency signal Acosωt is generated. The frequency multiplier 60 multiplies the frequency of the first radio frequency signal twice to generate a third radio frequency signal Acos (2? T−90 °) and applies it to the power control attenuator 70. The power control attenuator 70 generates a fourth radio frequency signal A-Δcos (2ωt-90 °) in which the power level of the third radio frequency signal is attenuated by the amount of power attenuation △ and the first band pass filter ( 80). The band pass filter 80 passes only the second harmonic included in the fourth radio frequency signal to generate a fifth radio frequency signal and applies it to the phase adjuster 90. The phase adjuster 90 changes the fifth radio frequency signal by a phase change amount Φ to generate a sixth radio frequency signal A-Δcos (2ωt−90 ° ± Φ).

On the other hand, the local oscillator 30 generates a national ball signal. The mixer 20 inputs and mixes the second radio frequency signal and the local signal, generates a first intermediate frequency signal, and applies it to the second band pass filter 40. The second band pass filter 40 removes harmonic components and the like contained in the first intermediate frequency signal, but cannot be completely removed due to nonlinear characteristics, and the second intermediate frequency signal BcosωIt + (A−δ) cos (ω t + Φ I). The power mixer 100 shifts the phase of the sixth radio frequency signal by 90 ° and mixes the second intermediate frequency signal to generate an intermediate frequency BcosωIt.

As described above, the present invention has the advantage of generating a pure intermediate frequency after removing a spurious component generated when the radio frequency signal and the local signal is converted to an intermediate frequency.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

Claims (3)

An intermediate frequency generating circuit of a wireless communication system, comprising: a wireless amplifier for amplifying a radio frequency signal received from an antenna; and a dividing electric shock level of the amplified radio frequency signal by the amplification means by 1/2 and having a phase of 90 °. A power divider for converting the transitioned first radio frequency signal and a second radio frequency signal whose phase does not change: a frequency multiplier for multiplying the frequency of the first radio frequency signal and outputting the result as a third radio frequency signal; A power control attenuator for reducing the power level of the third radio frequency signal by the amount of power attenuation and outputting the fourth radio frequency signal: outputting the second radio frequency signal as a fifth radio frequency signal by passing only the second harmonics included in the fourth radio frequency signal A first band pass filter and a phase adjuster for changing a phase of the fifth radio frequency signal according to a phase shift value and outputting the sixth radio frequency signal to generate a local signal. A local oscillator and a mixer for generating a first intermediate frequency signal after mixing and mixing the second radio frequency signal and a local signal, and removing the harmonic components included in the first intermediate frequency signal. And a second band pass filter for generating a signal and a power mixer for shifting the phase of the sixth radio frequency signal by 90 ° and mixing the intermediate frequency signal to generate an intermediate frequency. The intermediate frequency generating circuit of claim 1, wherein the power control attenuator is connected to an output terminal of the power mixer to change the amount of power control reduction to be equal to the power level of the second intermediate frequency signal. The intermediate frequency generator circuit of claim 1, wherein the phase adjuster is connected to an output terminal of the power mixer to change a phase shift value to be equal to a phase value of the second intermediate frequency signal.