SU603093A1 - Digital frequency synthesizer - Google Patents

Description

This invention relates to radio engineering and can be used as a stabil. frequency sources in radio devices. A digital frequency synthesizer is known, which contains a first tunable tuner, a mixer, a first band-pass filter, a variable divider frequency divider, a phase detector, and a first low-pass filter; in HTM, the output of the second tunable generator is connected to another mixer input the output of the reference source is connected to another input of the phase detector, and the input of the second band-pass filter JlJ is also connected to the mixer output. However, in a known synthesizer, the ability to control its dynamic characteristics is limited. The purpose of the invention is the phase stability of the output signals. For this purpose, a successively connected inverter and a second (} low frequency filter are introduced into the proposed digital frequency synthesizer between the other phase detector output and the control input of the second tunable oscillator. The drawing shows a structural electrical circuit of the proposed digital frequency synthesis. The device contains ringed the first tunable oscillator 1, the mixer 2, the first bandpass signal 3, the divider 4 frequencies with a variable division factor, the phase detector 5 and the first filter - 6 low frequencies, while the other input of the mixer 2 is connected; the output 7 of the second tunable generator 8, and the output of the source 10 of the reference signal are connected to the other input 9 of the phase detector 5, the input of the second band filter 11 is connected to the output of the second Another output of the phase detector 5 and the control input 12 of the second tunable generator 8 are connected in series with an inverter 13 and a second low-pass filter 14, except for that, the device includes an input 15 of the phase detector 5, an input 16 of the first lane tunable oscillator 1, the output synthesizer 17

pa, is a permanent divide 18 located between the source 10 of the reference signal and the input 9 of the phase detector 5.

The synthesizer works as follows, g

The frequencies of the first and second tunable oscillators 1 and 8 are mixed in mixer 2, and the first band-pass filter 3 selects the required transform band. frequencies (in this case, the difference), g that arrive at divider 4 with a variable division factor,

In divider 4, the frequency of the deltep is up to the value of the reference frequency fed to the input 15 of the phase detector 5.

Frequencies of the first in the second non-modifiable generators 1 and 8 that appear in the process of operation are compensated by controlling the "Synchronization condition in the detector" control for equalization of frequencies on inputs 1 and 9 and 15 of the phase detector 5,

The adjustment value in the dynamics of automatic control systems is found in. direct dependence on the gain control circuit. For linearized light, we have a second-order PLL for the frequency response of the open-loop system equal to

where J 0.01 - 0.05, it is possible to obtain an approximate dependence for the transition process times:

L "

Sp

"" one

In the considered PLL at aperiodic transition process

l-j

4KT

G}

at

where T is the constant time of the lowpass filter. It follows that with increasing K yo of a certain other name (to K “.“. I-)

4 t

i

j decreases.

With the introduction of communication from the exit with | of the detector 5 to the input 12 of the frequency control of the second nepecTpasmaeMoro oscillator 8 through the ventilation cascade - inverter 13 and the second low-pass filter 14; the adjustment ratio increases; In this case, it

Claims (1)

is determined by the formula NJVCjti,) jU (+ i (go K "JIS-SL ™ .-. - gain factor: ay regulation). Hence the regulation error, and therefore, the phase stability of the generated signals is higher, the more K. frequency synthesizer or the rate of establishment of transitional processes in the PLL system as an automatic control system is determined by the roots of the practical equation, the system. The transitional process can be considered to have ended if the term defined by the root closer to the imaginary axis decays. If the real root is closest to the imaginary axis, then the component in the transition process, determined by this root, has the form. (T. P tj is the root of the characteristic value, having found it at the end of the transition process., K. is the control of the first n the second rearrangeable oscillators 1 and 8f, which increases the phase stability of the generated signals and the speed of the frequency synthesizer tuning. Claim of the invention A digital frequency synthesizer containing the first tunable oscillator connected in a ring, the transmitter, the transducer a bandpass filter, a frequency divider with a variable division dividing factor, a phase detector s the first frequency filter, irn this the output of the second tunable oscillator is connected to another mixer input, and the output of the reference signal source is connected to another input of the phase detector, and the band input also is connected to another input of the phase detector filter, characterized in that, 414), in order to increase the phase stability of the high signals, between the other output of the phase detector and the control input of the second tunable generator are introduced Consequently, the inverter and the second low-pass filter, the Source of Information, are received in tm-manve with & 1. US Patent No. 37О6039, cl. 325-184, 25.06L1.