KR100734556B1 - Microwave wideband dynamic frequency divider - Google Patents

Abstract

A microwave wideband dynamic frequency divider is provided to remove an image frequency in a wideband with low power by coupling a variable phase shifter to an input terminal of the dynamic frequency divider. A microwave wideband dynamic frequency divider includes an image frequency removing mixer(100) having a phase shifter(110), a feedforward path divider(120), and a feedback path divider(130). The phase shifter(110) shifts a phase of an input frequency, and changes a phase change ratio variably. A control unit controls the phase shift ratio of the phase shifter(110) by determining an output signal element according to the input frequency to minimize a signal value of an unwanted frequency band. The phase shifter(110) has an RC-CR phase shifter structure, and forms a variable capacitor. The phase shifter(110) uniformly shifts a phase irrespective of the input frequency by varying the value of the variable capacitor according to the control of the control unit.

Description

Microwave Wideband Dynamic Frequency Divider

1 is a block diagram showing the configuration of a conventional general microwave dynamic frequency divider.

2A and 2B are diagrams illustrating an example of a phase shifter structure, and FIG. 2A illustrates an RC-CR phase shifter structure, and FIG. 2B illustrates a structure of a broadband phase shifter in which a RC-CR phase shifter is connected in multiple stages. drawing.

3 is a diagram illustrating a bandwidth of a conventional phase shifter.

Figure 4 is a block diagram showing the configuration of the microwave broadband active frequency divider of the present invention.

5 is a circuit diagram showing a configuration of a variable phase converter according to the present invention.

6A and 6B are diagrams conceptually showing an output frequency fout in the frequency domain according to the present invention, and FIG. 6A shows a desired output spectrum, and FIG. 6B shows a distortion component suppression diagram.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave wideband active frequency divider having a new structure which effectively reduces unwanted frequency components appearing at an output frequency in a wideband as an active frequency divider for receiving and dividing microwaves.

In recent years, high frequency frequency dividers in wireless communication systems have been considered as important factors in carrier generation and frequency synthesis.

In general, a Miller divider structure, which is a dynamic divider, is used as a frequency divider, and a divider using D flip-flop (D-F / F) is used as a static divider.

These frequency dividers are fixed at an integer multiple, so there is a limit to having various types of division ratios, for example, a few division ratios, and thus there is a limit to generating various desired output frequencies.

Therefore, a divider having a small frequency division ratio is implemented by combining a dynamic divider and a static divider in an appropriate manner using a frequency mixer.

However, when a general frequency mixer is configured as a combined use means of a dynamic divider and a static divider, an unwanted frequency component such as an image frequency component or an input signal component appears in an output signal, causing distortion.

In this case, an image frequency elimination mixer can overcome this problem. In order to drive the image frequency elimination mixer, a phase converter for converting an input signal into I / Q is required.

In general, a phase shifter includes a RC-CR phase shifter and a broadband phase shifter in which multiple RC-CRs are connected.

These phase converters may have a low bandwidth or a high power loss of the signal, which may reduce the performance of the final divider.

Therefore, implementing high performance divider requires a low loss phase shifter in broadband.

The present invention intends to propose a microwave broadband active frequency divider that improves the performance of a conventional divider using a variable phase shifter.

1 shows a configuration of a general microwave dynamic divider.

According to the conventional microwave dynamic frequency divider is a 1 / N static frequency divider (20) consisting of a video frequency cancellation mixer (10) using a Miller divider and its feedback path (feedback path) and feedforward path (feedforward path) By connecting 30 and appropriately selecting the operation of the static divider 20, 30 is a structure that can determine a small number of division ratios in various ways.

Looking at the operation in detail, the first feedforward static divider 20 in the feedforward path is operated, the second feedback static divider 30 in the feedback path is turned off, and the upper band is removed from the de-mixer. If selected, the division ratio is (N + 1) / N. If the lower band is selected, the division ratio is (N-1) / N.

Conversely, if the first feedforward static divider 20 of the feedforward path is turned off, the feedback static divider 30 of the feedback path is operated, and the output of the upper band is selected, the division ratio becomes N / (N-1), and the lower side Selecting a band has a division ratio of N / (N + 1).

At this time, by adjusting the frequency division ratio N of the static divider, the final division ratio can be adjusted to a desired value.

The image frequency removing mixer 10 needs a phase shifter 11 to change the phase of the input signal by 90 degrees.

Such a phase shifter 11 may be typically composed of a RC-CR phase shifter and a wideband phase shifter connected to the multi-stage.

2A and 2B are diagrams illustrating an example of a phase shifter structure, and FIG. 2A illustrates an RC-CR phase shifter structure, and FIG. 2B illustrates a structure of a broadband phase shifter in which a RC-CR phase shifter is connected in multiple stages. will be.

The phase shifters as described above have a common feature of converting phases 90 degrees into resistors and capacitors, respectively.

3 is a diagram illustrating a bandwidth of the phase shifter.

In general, as shown in FIG. 3, when the bandwidths of the wideband phase shifter and the RC-CR phase shifter are used, the wideband phase shifter may have a larger bandwidth to widen the operating range of the divider.

However, the wider the stage, the greater the power loss. In particular, in the microwave, the power loss is larger, which increases the power consumption of the entire divider, which is not suitable in the band using the microwave.

Equation 1 below shows the image frequency rejection ratio as a function of amplitude error and phase error.

Here, (ΔA / A) is amplitude error and θ means phase error.

Therefore, it can be seen that as the amplitude error and the phase error become larger, the overall image frequency rejection rate becomes worse.

If the amplitude error and the phase error of the phase converter 11 become worse, the image frequency rejection rate becomes worse, and thus the distortion of the divided signal becomes worse.

Therefore, it is important for the phase converter 11 to maintain the same amplitude and phase of the I / Q signal over a wide bandwidth.

As a result, the phase shifter 11 becomes an important factor in determining the operating range and performance of the active divider.

The present invention constructs an active divider that combines a dynamic divider, a Miller divider, and a static divider based on a flip-flop (DF / F) in the form of an image rejection mixer, and has a variable phase at an input terminal. We have proposed a microwave broadband active frequency divider that combines a transducer (a variable phase shifter) to remove the effective image frequency at low power in a wide band.

The present invention connects a 1 / N static divider comprising a feedback path and a feedforward path to an image frequency mixing mixer including a phase shifter for changing the phase of an input frequency and an image frequency mixer. And it has a structure to determine the division ratio in various ways according to the operation setting of the static divider,

And a control means for controlling the phase change rate of the variable phase converter by configuring the variable phase converter to vary the phase change rate in the phase converter of the image frequency elimination mixer and determining the output frequency according to the input frequency. It features.

 Referring to the embodiment shown in the accompanying drawings, the present invention having such a feature will be described as follows.

As shown in FIG. 4, the present invention connects a 1 / N static divider consisting of a feedback path static divider 130 and a feedforward path static divider 120 to an image frequency elimination mixer 100 using a Miller divider. Through the operation setting of the feedback static divider 130 and the feedforward static divider 120 has a structure that allows to determine various division ratio,

In order to minimize the value of the undesired output frequency in the image frequency elimination mixer 100, the phase of the input frequency fin is variably changed according to the set phase change rate, that is, the 90 degree phase difference according to the input frequency fin is changed. Configure the variable phase converter 110 that can be adjusted to make,

It comprises a control means (not shown) for controlling the phase change rate of the variable phase converter 110 by determining the output frequency (fout) according to the input frequency (fin).

The variable phase converter 110 follows the basic structure of the RC-CR phase converter and constitutes a variable capacitor Cv for determining the phase change rate, and according to the control signal Cs provided from the control means, the variable capacitor Cv. It is configured to make a 90 degree phase difference to obtain the desired output frequency (fout) according to the input frequency (fin) by changing the value of.

As described above, the present invention connects the 1 / N static dividers 130 and 120 formed of the feedback path and the feedforward path to the image frequency elimination mixer 100 using the Miller divider, and the feedback static divider 130 and the feedforward. Selective control of the operation of the static divider 120 constitutes an active frequency divider having a structure that allows various division ratios to be determined.

In order to obtain the desired output frequency fout, selective operation setting of the feedback static divider 130 or the feedforward static divider 120 is required, and the region of use of the apparatus prior to the use of the apparatus or in the manufacturing process (eg, Korea, Korea) That is, the operating state of the feedforward static divider 120 or the feedback static divider 130 is set according to the use frequency.

In one embodiment, the use frequency setting means (1 / N static divider setting means) is constituted, and the use frequency setting means includes means for inputting information of a use area, and the use of the area from this information. And a means for performing an operation setting (on or off) of the feed forward static divider 120 or the feedback static divider 130 according to the frequency.

At this time, one of the feed forward static separation 120 and the feedback static divider 130 is set to an on state, and the other is set to an off state.

That is, when the feed forward static divider 120 is set to the on state, the feedback static divider 130 is set to the off state, the feed forward static divider 120 is set to the off state, and the feedback static divider 130 is turned on. It is set.

In general, the image frequency elimination mixer 100 is composed of two mixers 101 and 102 and a phase converter for converting a phase of an input frequency (fin).

The phase shifter is configured as a variable phase shifter 110.

5 is a diagram illustrating a configuration of the variable phase converter 110.

According to this, the variable phase converter 110 has a basic structure that follows the RC-CR phase shifter, and forms a variable capacitor Cv to change the value of the variable capacitor Cv so that the phase shift can be performed regardless of the input frequency fin. It is configured to be made constant.

The value of the variable capacitor Cv for determining the phase shift value is determined according to the input frequency fin from the control means and is provided to the variable phase converter 110 as a control signal Cs. The value of the variable capacitor Cv of 110 is changed.

The control means outputs a control signal Cs for controlling the value of the capacitor Cv of the variable phase converter 110 to obtain the desired output force frequency fout according to the setting state of the 1 / N static divider. do.

That is, the control means generates a control signal Cs by checking the value of the output frequency fout output when the device is operated according to the use frequency band set in the use frequency setting means.

The control means includes information on the value of the output frequency relative to the input frequency and the value of the capacitor Cv for outputting the desired signal value, so as to check the output frequency fout and compare the desired signal value with the unwanted frequency. In order to minimize the component value, the control signal Cs for generating the capacitor Cv value of the variable phase converter 110 is generated from the above information.

In this way, an I / Q signal can be generated at a wider bandwidth than the RC-CR type, and power loss of the input signal can be minimized more than in a wideband phase shifter.

As the input signal is high in the microwave band, high power must be consumed to compensate for power loss. Therefore, minimizing power loss is a very important advantage in reducing power consumption of the entire circuit.

The operation of the present invention as described above is as follows.

Among the feed forward static divider 120 and the feedback static divider 130 composed of DF / F, the feedback static divider 130 is turned on and the feed forward static divider 120 is set to off. In the divider, the input frequency (fin) becomes a signal having a phase difference of 90 degrees through the variable phase shifter 110, and thus the signal having a phase difference of 90 degrees is an image frequency composed of two Miller dividers which are dynamic integrating periods. Input to the elimination mixer 100.

This frequency is mixed into the image frequency elimination mixer 100 as a feedback path in the feedback static divider 130 composed of D-F / F.

Here, the feedback signal from the feedback static frequency divider 130 is a signal input through the variable phase converter 110 is 90 degrees out of phase with each other.

Therefore, the signals mixed in the respective image frequency removing mixers 100 are added to each other, thereby eliminating the image frequency which is a harmonic component.

The signal from which the image frequency is removed becomes an output signal fout and also becomes an input signal of the feedback static divider 130.

Thereafter, the control unit checks the output frequency fout, adjusts the capacitor Cv value of the variable phase converter 110 to minimize an unwanted frequency band by determining an image frequency which is a harmonic component included in the output frequency. The control signal Cs is generated and output.

In the variable phase converter 110, the capacitor Cv is determined accordingly, and the input frequency fin is phase-shifted and output to the mixers 101 and 102 of the image frequency elimination mixer 100.

On the other hand, the feedback static divider 130 divides the output frequency fout previously output by the feedback path as described above by 1 / N and outputs it to the mixers 101 and 102.

In the mixers 101 and 102, the input frequency fin phase-converted through the variable phase converter 110 and the signal divided by the feedback static divider 130 are mixed, and the signal thereof is converted into an output frequency ( fout).

In this case, since there is no input signal of the initial feedback static divider 130, the initial input frequency fin becomes the input signal of the feedback static divider 130 of the feedback path as it is and is fed back while repeating the above process. It becomes an input signal of the divider 130.

The control means checks the output frequency fout and accordingly determines the value of the capacitor Cv for minimizing the unwanted frequency band included in the input frequency fin while repeating the above process. will be.

Similarly, when the feedforward static divider 120 is operated without using the feedback static divider 130, the input signal fin is directly input to the feedforward static divider 120 and has a phase difference of 90 degrees. The divided signal is input to the image frequency removing mixer 100.

In addition, the input signal fin becomes a signal having a phase difference of 90 degrees through the variable phase shifter 110, is input to the image frequency removing mixer 100, and mixed with each other in the mixers 101 and 102.

Each mixer's output signal is then summed to remove unwanted harmonics.

As described above, the control means checks the output frequency fout, and accordingly outputs a control signal Cs for determining the capacitor Cv value of the variable phase converter 110, and at the temporary displacement converter 110, By repeating the above process while varying the phase change rate in accordance with the signal, it is possible to obtain a desired signal without distortion.

6A and 6B are diagrams conceptually showing an output frequency fout in the frequency domain according to the present invention. FIG. 6A shows a desired output spectrum, and FIG. 6B is a distortion component suppression diagram.

The divided output signal as shown in FIG. 6A should be about 30 to 40 dBc larger than the unwanted harmonic signal. Otherwise, we can't see that unwanted harmonics have been removed and we can't make the signal we want.

In addition, in the general broadband active divider, as shown in FIG. 6B, image frequency suppression is performed in a wide band.

Such a wide band of suppression becomes the operating range of the active divider.

Applying the present invention as described above, it is possible to provide a microwave broadband active frequency divider capable of removing the effective image frequency at low power in the broadband.

Claims (2)

An image frequency elimination mixer including a phase shifter for changing the phase of the input frequency and a 1 / N static frequency divider composed of a feedback path and a feedforward path are connected to the image frequency mixer. In the active frequency divider having a structure that can determine the division ratio in accordance with the operation setting, The phase shifter of the image frequency elimination mixer is composed of a variable phase converter to variably change the phase change rate, and the output signal component according to the input frequency is judged to minimize the signal value of the unwanted frequency band. And a control means for controlling the rate of phase change of the microwave broadband active frequency divider. The method of claim 1, wherein the variable phase converter has a basic structure that follows the RC-CR phase converter, and constitutes a variable capacitor (Cv) to change the value of the variable capacitor (Cv) under the control of the control means to the input frequency A microwave wideband active frequency divider, characterized in that it is configured so that the phase shift can be made constant regardless of fin.

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