SU1127098A1 - Digital frequency synthesizer - Google Patents

Abstract

A DIGITAL SYNTHESIZER OF FREQUENCIES, containing a ring-connected first control, an avalable generator, a frequency divider with a variable division factor, a first phase detector and a first low-pass filter, connected in a ring of a second controllable: generator, mixer, band-pass filter, second phase detector and second a low-pass filter, a serially connected reference frequency sensor and a frequency grid former, the output of which is connected to another input of the second phase detector, and another output of the reference frequency sensor is connected to another input of the first phase detector, while the output of the first controlled oscillator is connected to another input of the mixer, which is blunt and so that, in order to improve performance and simplify the digital frequency synthesizer, between the output of the first low-pass filter and the second control A third low-pass filter is introduced by the input of the second controlled oscillator.

Description

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00 1 The invention relates to radio engineering and can be used for. Generals of a grid of highly stable oscillations in radio engineering devices for various purposes. A digital frequency synthesizer is known that contains a controlled oscillator, a controlled oscillator, a first mixer, a variable divider frequency divider, a phase detector and a low-pass filter, as well as two other autonomous tuning rings, the outputs of controllable oscillators of which are connected through series two the mixer and the frequency divider are connected to another input of the first mixer, and the second input of the phase detector is connected to the output of the reference generator ij. However, the speed of such a synthesizer is low, and the controlled oscillator must be pre-tuned using pre-set devices or auto-search devices so that its frequency is within the capture band. The closest in technical essence to the present invention is a digital frequency synthesizer containing ring-connected first controlled oscillator, frequency divider with variable division factor, first phase detector and first low-pass filter, connected in a ring second control generator, mixer , a bandpass filter, a second phase detector and a second low-pass filter, successively sour; an in-line reference frequency sensor and a frequency grid former, the output of which is connected to another input of the second phase Another output of the reference sensor is connected to another input of the first phase detector, while the output of the first controlled oscillator is connected to the other input of mixer 2 .. However, the lime digital frequency synthesizer has insufficient speed and is used for Additional devices for auto-searching or pre-setting frequency. The purpose of the invention is to increase the speed and simplify the digital frequency synthesizer. 8 The goal is achieved by the fact that a digital frequency synthesizer containing a first control generator, a variable frequency division divider, a first phase detector, and a first low pass filter, a second control generator, a mixer, a band pass filter, connected in series, The second phase detector and a second low-pass filter, a serially connected reference frequency sensor and a frequency grid former, the output of which is connected to another input of the second phase detector, and another output d reference frequency sensor connected to the other input of the first phase detector, wherein the first exercise vmkod: Aulus emogo oscillator connected to another input of mixer between high first lowpass filter and a second zt1; By controlling the input of the second controlled oscillator, a third low-pass filter is introduced. The drawing shows a structural electrical circuit of a digital frequency synthesizer. The device contains a reference frequency sensor 1, a frequency grid former 2, a first control oscillator 3, a frequency divider with a variable division factor {DPDK) 4, a first phase detector (PD) 5, a first low pass filter (LPF) 6, a second control oscillator 7, a mixer 8, a band-pass filter 9, a second PD 10, a second LPF 11, a third LPF 12. The digital frequency synthesizer works as follows. Sensor 1 generates highly stable oscillations of reference frequencies. The oscillations of the first reference frequency arrive at the input of the imager 2, which generates oscillations with a frequency determined by the tuning frequency code supplied to the control inputs of the imager. When the tuning frequency code is changed, the output frequency of the former 2 is changed in fine steps and afterwards goes to another input of the second PD 10. The frequency of the first controlled oscillator 3 is stabilized using the first phase locked loop consisting of DPDD 4, the first PD 5, the first low-pass filter 6, Setting the output frequency of the first controlled oscillator 3 is performed by setting the appropriate code of the division factor to control 3

At the inputs of the DPCD 4. When the code of the division ratio of the PDCD 4 at the output of the first controlled generator 3 changes, the frequency changes with a larger step than at the output of the driver 2 and enters the second input of the mixer 8, which is part of the output summing phase ring auto-tuning The output summing ring also includes a second controlled oscillator 7, a bandpass filter 9, a second PD 10, and a second low pass filter 11.

The first and second controlled generators 3 and 7 are similar. When adjusting the digital frequency synthesizer, they are adjusted so that, with the same control voltage applied to the inputs of the controlled oscillators 3 and 7, the frequency of the second controlled oscillator 7 exceeds the frequency of the first controlled oscillator 3 by the amount of the tuning frequency of the band-pass filter 9. When This, at the first input of the second controlled generator 7, when adjusting, supplies the voltage, the average between the minimum and maximum values of the voltage produced by the second PD. Therefore, the core component allocated to the third LPF 12 from the control voltage of the first s ™ | equal oscillator 3 and fed to the second control input of the second control oscillator 7, at any output frequency of the first ring

The ki sets the frequency of the second controlled oscillator 7 such that the difference frequency signal at the output of the mixer 8 is always in the passband of the band-pass filter 9, and the output summing ring of the phase auto-tripod is in the capture mode. The second PD 10 compares the oscillation phases from the output of the bandpass filter 9 and from the output of the shaping body 2 and produces a control voltage that, through the second low pass filter 11, adjusts the frequency of the second controlled oscillator 7 to a nominal value equal to

15 frequencies of the output oscillation of the driver 2, and the first phase locked loop. Thus, presetting the frequency of the second control oscillator 7 using the voltage from the third low-pass filter. 12 eliminates the need for a sophisticated auto-search device and greatly simplifies the digital frequency synthesizer. Since, when tuning the frequency of the first ring of the phase-locked loop, the second control generator 7 of the output ring of the phase-locked loop is simultaneously tuned,

30 is not an exit from the capture band, then the operation of introducing the frequency of the second controlled oscillator 7 into the capture band, for which the final time is spent, in the proposed digital

35 frequency synthesizer is missing, which increases its speed.

Claims (1)

A DIGITAL FREQUENCY SYNTHESIZER comprising a first controlled oscillator connected in a ring, a variable frequency divider, a first phase detector and a first low-pass filter, a second controlled generator, a mixer, a band-pass filter, a second phase detector and a second low-pass filter, followed by · Carefully connected reference frequency sensor and frequency shaper, the output of which is connected to another input of the second phase detector, and the other output of the reference frequency sensor is connected to another the input of the first phase detector, while the output of the first controlled oscillator is connected to another input of the mixer, in order to increase the speed and simplify the digital frequency synthesizer, between the output of the first low-pass filter and the second control input of the second controlled generator third low pass filter. 1 1127098 2