SU871342A1 - Frequency synthesizer - Google Patents

Description

(54) FREQUENCY SYNTHESIZER

I

The invention relates to radio engineering and can be used for frequency synthesis in various radio engineering devices.

A known frequency synthesizer containing a serially connected tunable generator, a frequency divider with variable dividing factor, a pulse phase detector and a low pass filter, a frequency detector serially connected and a sawtooth voltage driver, the output of which is connected to one of the control inputs of the tunable generator, and synchronization control device, the input of which is connected to the output of the frequency detector, another input of which is connected to the rotary input of the pulse-phase go detector 1.

However, the known frequency synthesizer has a relatively narrow frequency tuning range due to the fact that the tunable generator can be installed with a frequency-locked frequency (FMF) ring in almost any point of the holding band of the phase-locked loop (FAP), which leads to a two-way tuning of the synthesizer Frequencies without synchronization of the PLL can only be performed in a narrow frequency range.

The purpose of the invention is to expand the frequency tuning range without synchronizing.

For a frequency synthesizer containing a serially connected tunable oscillator, a frequency divider with a variable division factor, pulse-phase

10 a detector and a low-pass filter connected in series with a frequency detector and a sawtooth voltage driver, the output of which is connected to one of the control inputs of a tunable oscillator, and

15 synchronization control device, the input of which is connected to the output of the frequency detector, the other input of which is connected to the other input of the pulse-phase detector, between the output of the synchronization control device

Claims (1)

20 and another control input of the tunable generator include a series-connected threshold device, a first key and an adder, and a second key is connected between the other output of the threshold device and the output of the first key. A low-pass filter output is connected to another input of the threshold device and another adder input. The drawing shows the page of the electrical circuit of the proposed device. The frequency synthesizer contains a tunable oscillator 1 divider with variable division factor (DPDD) 2, a pulse-phase detector (IFD) 3, a frequency detector (RR) 4, a sawtooth voltage driver 5, a low-pass filter (LPF) 6, an adder 7, synchronization control device 8, threshold device 9, first 10 and second 11 keys. The frequency synthesizer works as follows. The PLL synthesizer ring includes a tunable generator 1, DPKD 2, IFD 3, LPF 6, a ring CHAL — a controlled generator DPKD 2, BH 4, a sawtooth driver 5, a synchronization control device 8, a threshold device 9, keys 10, 11 and the adder 7. After turning on the frequency synthesizer, the LAP ring operates, while the output of the synchronization control device 8 sends an out of sync signal to the setup input of the threshold device 9, the threshold device 9 sets the keys 10, 11 in such a way that of these, there is no voltage, and at the output of the other there is a voltage U, which is summed up by the sum of torus 7 with the voltage at the output of the low-pass filter 6. The most optimal case is when threshold device 9 has two thresholds, Uj and Uj, where DZ U ,. Some time after the end of the search, a synchronization signal is sent to the installation input of the threshold device 9 from the output of the synchronization control device 8; 1) if Tsvyhfnch ™ is the output of both keys 10, 11, there is no voltage 2) if ir, fu, - the output of both keys 10, 11 is voltage U. 3) if Ui and 0y, fc, U2 - voltage to the output of the keys 10 and does not change. In the first two cases, the seizure occurs in the extreme areas of the retention band, however, the PLL ring thus works out a change in voltage on the keys 10 and 11 that the operating point moves to the middle part of the retention band, where Cfcch Uj. In this way, a two-way tuning of the frequency synthesizer without synchronization is provided to a value of not less than t Э rVH rvH РУ ™ sign of the controlled oscillator 1 In the case of a frequency synthesizer operating in the range of 80-90 MHz with a hold band of 2 MHz, the keys and the adder were provided for two-way rebuilding without synchronization by an amount of at least t 0.7 mHz. Without installing additional nodes, the minimum value of bilateral adjustment without synchronization was + 0.15 MHz. Such an extension of the two-way re-tuning region without synchronization disturbance may allow reducing the communication time and increasing the reliability of information transmission in communication systems. Formula of the Invention Frequency Synthesizer containing serially connected tunable geerator, frequency divider with variable division factor, pulse-phase detector and filter of them frequencies, serially connected frequency detector and shaper sawtooth voltage, the output of which is connected to The inputs of the tunable oscillator, as well as the synchronization control device, the input of which is connected to the output of the frequency detector, the other input of which is connected to another input of the pulse phase detector, characterized in that in order to extend the frequency tuning range without synchronization, between the output of the device synchronization control and another control input of the tunable generator are connected in series the threshold device, the first key and the adder, and between the other output ovogo device and the output of the first switch the second switch is turned on, the output of the lowpass filter is connected to another input of the threshold device and the other input of the adder. Sources of information taken into account in the examination 1. USSR author's certificate. N 387488, cl. NOSM 3 / 04,1971 (prototype).