KR100527600B1 - Wide band frequency generator for improving phase noise - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wideband frequency generator with improved phase noise. In detail, the frequency control is simple by synthesizing a frequency using one oscillator and comparing the frequency with a main oscillator through a divider. Noise can be improved.

Description

Wideband frequency generator with improved phase noise {WIDE BAND FREQUENCY GENERATOR FOR IMPROVING PHASE NOISE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency generator. Specifically, a frequency is synthesized using one oscillator and then compared with the frequency of the main oscillator through a divider to simplify frequency control and improve phase noise. The invention relates to a wideband frequency generator with improved noise.

In general, when designing a spectrum analyzer or signal generator, it is a high band as a main oscillator of frequency, and uses a YTO (Yig Tuned Oscillator) or a VCO (Voltage Control Oscillator) that generates a wide band frequency, and uses an output frequency. To be arbitrarily controllable, the circuit must be implemented using a phase lock loop (hereinafter referred to as a 'PLL') circuit. However, when implementing a PLL circuit, two or more frequency components are required to be compared. One uses the main generator component, and the other is generated within the circuit itself, called a sample PLL circuit. In this case, as shown in FIGS. 1 and 2, a PLL circuit using a plurality of voltage controlled oscillators (VCOs) is implemented, a frequency is generated, and a signal close to the main oscillator is generated through a multiplier. The frequency is controlled by performing a PLL by comparing two signals.

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However, as shown in FIG. 1, the conventional sample PLL circuit forms a multi-stage PLL to subdivide the frequency to fine-tune the frequency control, and the phase noise is sharply deteriorated by multiplying the frequency at the final stage multiplier. And, there is a problem that is affected by the phase noise of the voltage controlled frequency generator used therein. The phase noise of the internal voltage-controlled frequency generator is difficult to design for optimal performance, and the phase noise of the voltage-controlled frequency generator itself is deteriorated due to the formation of a PLL at each stage.

Also, as shown in FIG. 2, the conventional sample PLL circuit is a method of designing a frequency generator using only a multiplier without using a PLL, which has a very limited use range since the generated frequency is a specific frequency. Another problem is that the phase noise characteristic is deteriorated due to the use of exhaust.

Accordingly, an object of the present invention is to solve the above problems, and synthesize the frequencies using one oscillator and compare the frequency of the main oscillator with a divider so that frequency control is simple and phase noise is reduced. To improve.

Features of the present invention for achieving the above object,

A reference frequency generator for generating a reference frequency signal,

A multiplier for generating a frequency by three times the reference signal generated from the reference frequency generator;

A power divider for dividing the signal filtered from the divider into two powers and outputting the same through each output stage;

A frequency variable for varying a frequency of a signal output from the power divider through a first pass;

A first mixer for mixing and up-converting the frequency output through the second pass of the power divider and the frequency output through the frequency variable;

A 1/2 divider for dividing and outputting the frequency signal passed through the first mixer by two;

The signal output through the 1/2 divider is multiplied according to the Q value, and the frequency is adjacent to the frequency of the main generator through the frequency output from the second mixer by comparing the frequency with the frequency of the main generator of the system. With multiplier to collect in,

And a second mixer for generating and outputting a difference between a frequency output from the multiplier and a frequency input from a main generator of the system.

Here, between the first output terminal of the power divider and the frequency variable,

A first amplifier for amplifying the signal output through the first pass from the power divider is further provided,

Between the second output terminal of the power divider and the first mixer,

A second amplifier for amplifying the signal output through the second pass from the power divider is further provided,

Between the 1/2 divider and the multiplier,

A third amplifier for amplifying the signal output through the 1/2 divider is further provided.

Here also between the distributor and the power divider,

Further provided is a first band pass filter for passing only a frequency of a predetermined band of the frequency generated by the divider

Between the frequency variable and the first mixer,

It is further provided with a low pass filter for passing only a signal of a predetermined band or less of the frequency output from the frequency variable,

Between the second amplifier and the first mixer,

A second band pass filter for passing only a frequency of a predetermined band of the frequency output through the second amplifier is further provided,

Between the first mixer and the 1/2 divider,

A third band pass filter is further provided to pass only a frequency of a predetermined band required among the frequencies output through the first mixer.

Here, between the first output terminal of the power divider and the first amplifier,

Further provided is a first pad configured by placing a resistor in the form of pi (π) to block the impedance of the abnormality caused by the input impedance of the first amplifier and the output of the power divider collide,

Between the first amplifier and the frequency variable,

The second pad is further provided with a pie (π) -type resistor is arranged to block through the impedance matching the input impedance of the frequency variable and the output of the first amplifier collides,

Between the second output stage of the power divider and the second amplifier,

The third pad is further provided with a pie (π) type resistor is arranged to block the impedance of the input impedance of the second amplifier and the output of the power divider through an impedance matching to prevent the occurrence of abnormality,

Between the second band pass filter and the first mixer,

The fourth pad may further include a pi-shaped resistor disposed to block an impedance phenomenon from collision between an input impedance of the first mixer and an output of the second band pass filter.

Hereinafter, the configuration of the broadband frequency generator with improved phase noise according to the present invention will be described in detail with reference to FIG.

3 is a block diagram schematically showing the configuration of a wideband frequency generator with improved phase noise according to the present invention.

Referring to FIG. 3, the broadband frequency generator 100 with improved phase noise according to the present invention includes a reference frequency generator 110, a divider 120, a first band pass filter 130, and a power distribution. Period 140, first amplifier 150, frequency variabler 160, low pass filter 170, second amplifier 180, second band pass filter 190, first The mixer 200, the third band pass filter 210, the half divider 220, the third amplifier 230, the multiplier 240, and the second mixer 250 are provided. .

The reference frequency generator 110 generates a reference frequency signal of 100 MHz.

The divider 120 triples the reference signal generated from the reference frequency generator 110 to generate a 300 MHz frequency. Here, the multiplier 120 triples the frequency to generate an additional signal such as 100 MHz, 200 MHz, 300 MHz, 400 MHz, and 500 MHz instead of generating a signal of 300 MHz.

The first band pass filter 130 has a bandwidth of 30 MHz, and passes only a frequency of 300 MHz among the frequencies generated by the divider 120.

The power divider 140 separates the filtered signal (6dB) from the first band pass filter 130 into two powers, and distributes the output through a Y-shaped connection of a resistor.

The first amplifier 150 amplifies the signal of 300MHz output from the power divider 140 through the first pass to a required level at a later stage.

The frequency variabler 160 amplifies the frequency amplified and input through the first amplifier 150. Here, the frequency variabler 160 has a reference signal of 300 MHz and can control up to a 0.4 * reference signal (120 MHz) band signal.

Since the low pass filter 170 has a characteristic of Sin (x) / x function because the signal of the frequency variabler 160 has a characteristic of Sin (x) / x function, 120MHz of the frequency output from the frequency variabler 160 is outputted together. Only the following signals are passed. Here, the band of the low pass filter 170 should be smaller than the reference frequency / 2.

The second amplifier 180 amplifies the 300 MHz signal output from the power divider 140 through the second pass to a required level at a later stage.

The second band pass filter 190 has a bandwidth of 30 MHz, and passes only a frequency of 300 MHz among frequencies generated by the second amplifier 180.

The first mixer 200 mixes the frequency of 300 MHz input through the second band pass filter 190 and the frequency input through the low pass filter 170 to up-convert and output the mixed signal.

The third band pass filter 210 has a bandwidth of 10 MHz and passes only a frequency of 405 MHz among signals output through the first mixer 200.

The 1/2 divider 220 divides the frequency signal passed through the third band pass filter 210 into two to generate and output a frequency required by the multiplier 240. In this case, an effect of improving phase noise due to two-division of frequency in the 1/2 divider 220 occurs.

The third amplifier 230 amplifies the signal output through the 1/2 divider 220 to a level for driving the rear multiplier 240.

When the multiplier 240 has a Q value of 17 to 34, the multiplier 240 multiplies the signal output through the third amplifier 230 17 to 34 and compares the frequency with the frequency of the main generator 1 of the system. The frequency is output from the mixer 2 to the frequency adjacent to the frequency of the main generator (1).

The second mixer 250 generates a difference between a frequency output from the multiplier 240 and a frequency input from the main generator 1 of the system, and converts the frequency into a low band and outputs the frequency.

Meanwhile, between the first output terminal and the first amplifier 150 of the power divider 140, between the first amplifier 150 and the frequency variabler 160, and the second output terminal and the second output terminal of the power divider 140. Pi between two amplifiers 180 and between the second band pass filter 190 and the first mixer 200 so that an abnormal phenomenon occurs due to a collision between the input impedance and the output of the rear stage through impedance matching. The first to fourth pads 260 to 290 configured by disposing a shape of the shape are further provided.

Hereinafter, the operation of the broadband frequency generator with improved phase noise according to the present invention will be described in detail with reference to FIG. 3.

First, when the reference frequency generator 110 generates and outputs a 100 MHz reference frequency signal, the divider 120 triples the reference signal generated from the reference frequency generator 110 to generate a 300 MHz frequency.

Then, the first band pass filter 130 passes only a frequency of 300 MHz among the frequencies generated by the divider 120, and the power divider 140 transmits two signals to the signal filtered from the first band pass filter 130. And print it out.

Meanwhile, the signal output from the first pass of the power divider 140 is impedance-matched through the first pad 260, and the signal output from the second pass of the power divider 140 is the second pad 270. Impedance matching is achieved through

In the state where impedance matching is made through the first pad 260, the 300 MHz signal output from the power divider 140 is amplified to the required level in the frequency variabler 160 through the first amplifier 150, which is again Impedance matching is performed through the third pad 280.

In the state where impedance matching is made through the third pad 280, the signal output from the first amplifier 150 is varied in frequency through the frequency variabler 160 and output to the low pass filter 170. 170 passes only signals of 120 MHz or less among frequencies output from the frequency variabler 160.

Meanwhile, a signal of 300 MHz output from the power divider 140 is amplified to the required level in the frequency variabler 160 through the second amplifier 180 in the state where impedance matching is made through the second pad 270. Filtered by a two band pass filter 190.

The signal passing through the second band pass filter 190 is input to the first mixer 200 in a state where impedance matching is made through the fourth pad 290.

Then, the first mixer 200 is up-converted by mixing the frequency output from the second band pass filter 190 and input through the fourth pad 290 and the frequency input through the low pass filter 170. This signal is passed through the third band pass filter 210 of only the frequency of 405MHz of the signal output through the 1/2 divider 220 is input, the half divider 220 is the frequency signal 2 By dividing, the frequency required by the multiplier 240 is generated and output.

When the third amplifier 230 amplifies and outputs the signal output through the 1/2 divider 220 to a level for driving the multiplier 240 at the rear stage, the multiplier 240 outputs the signal 17 to 17. The sampling frequency is compared with the frequency of the main generator 1 of the system, and the frequency is output to be adjacent to the frequency of the main generator 1 through the frequency output from the second mixer 250.

Then, the second mixer 250 generates a difference between a frequency output from the multiplier 240 and a frequency input from the main generator 1 of the system, and converts the frequency into a low band and outputs the frequency.

Therefore, the phase noise of the frequency generator depends on the voltage-controlled oscillator, phase detector, and internal PLL bandwidth located therein, and deteriorates according to the number of use of the voltage-controlled oscillator. Thus, in the present invention, frequency is divided by one reference frequency generator. After the sampling, the frequency is compared with the main frequency of the system, and the frequency is adjusted and output according to the comparison result, thereby providing a low-frequency frequency generator with good phase noise characteristics.

As described above, according to the broadband frequency generator with improved phase noise according to the present invention, frequency control is simple by synthesizing frequencies using one oscillator and comparing the frequency with the main oscillator through a divider. Therefore, phase noise can be improved.

1 is a block diagram schematically showing the configuration of a conventional sample PLL circuit.

2 is a block diagram schematically showing the configuration of a conventional sample PLL circuit.

3 is a block diagram schematically showing the configuration of a broadband frequency generator with improved phase noise according to the present invention.

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

110: reference frequency generator 120: distributor

130: first band pass filter 140: power divider

150: first amplifier 160: frequency variable

170: low pass filter 180: second amplifier

190: second band pass filter 200: first mixer

210: third band pass filter 220: 1/2 divider

230: third amplifier 240: multiplier

250: 2nd mixer 260-290: 1st-4 pad

Claims (4)

A reference frequency generator for generating a reference frequency signal, A multiplier for generating a frequency by three times the reference signal generated from the reference frequency generator; A power divider for dividing the signal filtered from the divider into two powers and outputting the same through each output stage; A frequency variable for varying a frequency of a signal output from the power divider through a first pass; A first mixer for mixing and up-converting the frequency output through the second pass of the power divider and the frequency output through the frequency variable; A 1/2 divider for dividing and outputting the frequency signal passed through the first mixer by two; The signal output through the 1/2 divider is multiplied according to the Q value, and the frequency is adjacent to the frequency of the main generator through the frequency output from the second mixer by comparing the frequency with the frequency of the main generator of the system. With multiplier to collect in, And a second mixer for generating and outputting a difference between a frequency output from the multiplier and a frequency input from a main generator of the system. The method of claim 1, Between the first output terminal of the power divider and the frequency variable, A first amplifier for amplifying the signal output through the first pass from the power divider is further provided, Between the second output terminal of the power divider and the first mixer, A second amplifier for amplifying the signal output through the second pass from the power divider is further provided, Between the 1/2 divider and the multiplier, And a third amplifier for amplifying the signal output through the 1/2 divider. The method of claim 2, Between the distributor and the power divider, A first band pass filter for passing only a frequency of a predetermined band of the frequencies generated by the divider is further provided, Between the frequency variable and the first mixer, It is further provided with a low pass filter for passing only a signal of a predetermined band or less of the frequency output from the frequency variable, Between the second amplifier and the first mixer, A second band pass filter for passing only a frequency of a predetermined band of the frequency output through the second amplifier is further provided, Between the first mixer and the 1/2 divider, And a third band pass filter for passing only frequencies of a predetermined band among the frequencies output through the first mixer. The method of claim 2, Between the first output stage of the power divider and the first amplifier, Further provided is a first pad configured by placing a resistor in the form of pi (π) to block the impedance of the abnormality caused by the input impedance of the first amplifier and the output of the power divider collide, Between the first amplifier and the frequency variable, The second pad is further provided with a pie (π) -type resistor is arranged to block through the impedance matching the input impedance of the frequency variable and the output of the first amplifier collides, Between the second output stage of the power divider and the second amplifier, The third pad is further provided with a pie (π) type resistor is arranged to block the impedance of the input impedance of the second amplifier and the output of the power divider through an impedance matching to prevent the occurrence of abnormality, Between the second band pass filter and the first mixer, Further provided is a fourth pad configured by arranging a pi (π) type resistor to block an impedance match between an input impedance of the first mixer and an output of the second band pass filter. A wideband frequency generator with improved phase noise.