SU1755371A1 - Frequency modulated digital frequency synthesizer - Google Patents

Description

equal generator and frequency divider of the carotid characteristic, entered 4 second

variable division factor, ip low pass filter and adder, first and

the modulating signal source, the output of the ko-second inputs and the output of which is correspondingly connected to the modulating signal, are connected to the output of the first filtered-out generator and to the input of the low-pass integra-5, to the output of the controlled

a torus, a frequency setting unit, the output of which is an attenuator and to the control input of the upgo is connected to the installation input of the emitted generator; input and output of second half frequencies with variable coefficient low pass filter, respectively

The division switch and with the control input are connected to the integrator output and from the co-attenuator, which differs by 10 inputs of the controlled attenuator by the fact that, in order to extend the range, the output of the frequency divider with variable

modulating frequencies with a simultaneous division factor is connected to an increase in the non-uniformity of the modulus to the input of the phase detector.

Claims (5)

Formula of the invention A frequency-modulated digital frequency synthesizer comprising a controlled attenuator, a reference oscillator, a frequency divider, a phase detector and a first low-pass filter connected in series to a series 5 simultaneously reducing the unevenness of the modulation characteristic. The drawing shows an electrical block diagram of a digital frequency synthesizer with frequency modulation. The digital frequency synthesizer with frequency modulation contains a reference generator 1, a divider 2 frequencies, phase detector (PD) 3, the first filter 4 low frequencies (low-pass filter), adder 5, controlled oscillator 6, frequency divider 7 with variable division coefficient (DPKD), modulating signal source (IC) 8, integrator 9, second low-pass filter 10, controlled attenuator 11, frequency setting unit 12. A digital frequency synthesizer with frequency modulation operates as follows. In the synchronism mode without supplying modulating voltage, the signal from the controlled generator 6 with a frequency fyr is fed to the input of the DPKD 7, where it is divided by the frequency by. the division coefficient from the output DPKD 7 sig. cash in the form of short pulses with a frequency fyr / N goes to the second input of PD 3, to: the first input of which through the frequency divider 2 receives short reference pulses from the reference generator 1. From the output of the PD 3 slowly changing control voltage (by the principle of negative feedback) through the first low-pass filter 4 and the adder 5 enters the control input of the controlled generator 6 and adjusts it in frequency and phase to the reference generator 1. Thus, the phase-locked loop fulfills (reduces) the change in the frequency of the controlled oscillator 6, starting with the lowest and ending with the cut-off frequency of the first low-pass filter 4. Above the cut-off frequency 45 of the first low-pass filter 4, the controlled oscillator and the phase ring quickly leave. howling auto-tuning is not practiced (not reduced). When applying the modulating voltage from the IC 8 to the modulating input of the controlled generator 6, its frequency modulation occurs (as in the usual direct single-point method). At. At the same time, at the output of the first low-pass filter 4 (or, respectively, at the first input of the adder 5) in the general control signal there is a component from the reaction of the auto-tuning ring to the modulating disturbance of the controlled oscillator 6 in the frequency band from the lowest to the cutoff frequency of the first low-pass filter 4. 5 . '17 an equalizable generator and a frequency divider with a variable division coefficient, a modulating signal source whose output is connected to the modulating input of a controlled generator and an integrator input, a frequency setting unit, the output of which is connected to the installation input of a frequency divider with a variable division coefficient and with a control input of a controlled attenuator, which is based on the fact that, in order to expand the range of modulating frequencies while reducing modulation unevenness 71 ⁶ 'characteristics, a second low-pass filter and an adder are introduced, the first and second inputs and output of which are respectively connected to the output of the first low-pass filter, to the output of the controlled attenuator and to the control input of the controlled generator, the input and output of the second low-pass filter frequencies respectively Connected to the output of the integrator and the signal input of the controlled attenuator, the output of the frequency divider with a variable division ratio is connected to the second input of the phase detector. Editor Y. Sereda Compiled by Y. Kovalev Tehred M. Morgenthal Corrector T, Paly Order 2898 Circulation Subscription VNIIIPI of the State Committee for Inventions and Discoveries at the State Committee for Science and Technology 113035, Moscow, Zh-35, Raushskaya nab .. 4/5 Production and Publishing Plant Patent ”, Uzhgorod, 101 Gagarina St.