SU770544A1 - Frequency synthesizer - Google Patents

Description

The invention relates to a technique of digital frequency synthesis and can be used in radio communication equipment, radar, measurement technology and remote control devices.

A known frequency synthesizer, containing in series, a connected reference frequency generator, a phase detector, an adder, a low-pass filter, a synchronized oscillator, and a frequency divider with a variable division factor, the output of which is connected to another input of the phase detector 00 ·

The disadvantage of the known synthesizer | 5 frequencies is the presence in the output oscillation spectrum of the harmonics of the reference frequency, formed by the passage of the fronts of the sampling pulse of the phase detector into the control signal. 20

The purpose of the invention is to improve the suppression of the harmonics of the reference frequency in the spectrum of output oscillations.

To this end, a frequency synthesizer containing a 25 reference frequency generator, a phase detector, an adder, a low-pass filter, a synchronized oscillator, and a frequency divider with a variable division factor, the output of which is connected is 30

2

A serially connected amplifier, a second low-pass filter, an integrator, an analog storage device and an amplifier with adjustable gain, whose signal input is connected to the output of the phase detector, are entered with another input of the phase detector, between the output of the adder and another input of the adder.

The drawing shows a structural electrical circuit of the proposed device.

The frequency synthesizer contains a reference frequency generator 1, a phase detector 2, an adder 3, a low-pass filter 4, a synchronized oscillator 5, a frequency divider with a variable division factor b, an amplifier with adjustable gain 7, an amplifier 8, a low-pass filter 9, an integrator 10 and analog storage device 11. The output of the synchronized generator is the output of the frequency synthesizer.

In the proposed frequency synthesizer

reference harmonic suppression

in the spectrum of output oscillations is as follows.

3

770544

The parasitic pulses formed by the passage of the fronts of the sampling phase detector 2, the output of the latter is fed to the inputs of the adder 3 I and an amplifier with adjustable gain 7, which is a high-speed pulse amplifier-inverter. From the output of the amplifier With adjustable gain, a pulse of opposite polarity is fed to the second input of the adder Z. The output of the adder is the algebraic sum of both pulses through the amplifier 8 is fed to the input of the low-pass filter 9, where the constant component of the specified amount is allocated, which through the integrator 10 is fed to the analog input the storage device 11, where it is stored and stored. The output signal of the analog storage device is fed to the control input of the amplifier with an adjustable gain of 7 to adjust the gain of the latter so that the algebraic sum of both pulses is zero.

The proposed frequency synthesizer has high spectral characteristics due to improved suppression of the harmonics of the reference frequency in the spectrum of output oscillations, is simple in design and technical implementation, and can be easily implemented and used in high-quality radio devices.

Claims (1)

Claim A frequency synthesizer containing a series-connected reference frequency oscillator, a phase detector, an adder, a first low pass filter, a synchronized oscillator, and a frequency divider with a variable division factor, the output of which is connected to another input of the phase detector, wherein , 5 that, in order to improve the suppression of the harmonics of the reference frequency in the spectrum of output oscillations, serially connected between the output of the adder and the other input of the adder 20 amplifier, second low pass filter, integrator, analog storage device and variable gain amplifier, the signal input of which is connected - to the output of the phase detector.