SU470902A1 - Frequency synthesizer - Google Patents

Description

one

The present invention relates to radio engineering and can be used in radio communication systems and in instrumentation.

A known frequency synthesizer comprising a frequency setting unit, a reference generator, a first self-tuning ring consisting of a first controlled oscillator included in the ring, a first divider with a variable division factor and a first phase discriminator, a second auto-tuning ring comprised of second control generator, a second divider with a variable division factor, and a second phase discriminator, the third auto-tuning ring, consisting of the third tunable the generator, the mixer and the third phase discriminator, the output of the first controlled generator through the first divider with a constant division factor is connected to the second input of the third phase discriminator, and the output of the reference generator is connected directly to the second input of the mixer and through the third divider with a variable division factor - with the second input of the first phase discriminator, and the outputs of the frequency setting block are connected to the control inputs of the first and second dividers with a variable coefficient om division

The disadvantage of the known device lies in a large parasitic modulation of the output signal of the frequency base along the second self-tuning loop.

In order to reduce the parasitic frequency modulation of the output signal in the proposed synthesizer, between the output of the third tunable generator and the second input of the second phase discriminator is included

the second divider with the nominal dividing ratio, and the control input of the third divider with a non-timed dividing ratio connected to the control input of the second divider with a variable division factor.

The drawing shows a structural diagram of the proposed device.

The device consists of a reference generator 1, a frequency setting unit 2, a first divider 3 with a constant division coefficient, a divider 4 with a variable division factor, a second divider 5 with a constant division factor, and three self-tuning rings.

The first self-tuning ring contains the first adjustable oscillator 6 included in the ring, the first divisor 7 with a variable coefficient of deletion and the first phase discriminator 8.

The second ring loop contains

a second controlled oscillator 9, a second divider 10 with a variable division factor, and a second phase discriminator 11.

The third self-tuning ring consists of a third tunable generator 12, a mixer 13 and a third phase discriminator 14. The output of the first controlled generator 6 is connected via a nerve divider with a constant division factor 3 to the second input of the third phase discriminator 14, and the output reference the generator 1 is connected directly to the second input of the mixer 13 and through a divider 4 with a variable division factor to the second input of the first phase discriminator 8.

The outputs of the frequency setting unit 2 are connected to the control inputs of the first and second dividers 7 and 10, respectively.

The frequency setting unit 2 contains switches, for example, of the decade type. The lower bits change the division factor n of the divider 7, the higher bits change the division coefficient n and the divisors 4 and 10 simultaneously.

To clarify the principle of frequency control / 9, the equation of the established process is written down at the output of the synthesizer, and there is no frequency detuning in the auto-tuning rings.

/one

/ 1 "7

 --"ten.

L4 "3" 6 "6

When simultaneously changing the coefficients of rtio and "4, it is easy to ensure

- ziz e const,

"four

for example, e l const, when. In this case

f.:f, + f ,, IB “C 5

That is, the frequency / d is linearly dependent on the coefficients Pu and “7 Stand frequency / i is excluded from the second ring of auto-tuning and is extremely constant. This achieves a small parasitic modulation of the output signal of the frequency pedestal.

Subject invention

A frequency synthesizer containing a frequency setting block, a reference oscillator, a first self-tuning ring consisting of the first controlled oscillator included in the ring, a first divider with a variable division factor, and a first phase discriminator, a second self-adjusting ring consisting of the second controlled oscillator included in the ring a generator, a second divider with a variable division factor, and a second phase discriminator; a third self-tuning ring consisting of a third tunable gene included in the ring the first phase generator through the first divider with a constant division factor connected to the second input of the third phase discriminator, and the output of the reference generator directly connected to the second input of the mixer and through the third divider with a variable division factor - with the second input of the first phase discriminator, and the outputs of the frequency setting block are connected to the control inputs of the first and second dividers with a variable factor In order to reduce the parasitic frequency modulation of the output signal, a second divider with a constant division factor is connected between the output of the third tunable generator and the second input of the second phase discriminator, and the third divider with a variable division factor is connected to the control the input of the second divider with a variable division factor.