SU486450A1 - Frequency synthesizer - Google Patents

Description

one

Known frequency synthesizer containing successively included reference oscillator, frequency divider, first key and frequency counter. The outputs of the latter are connected to the first group of inputs of a digital-to-analog converter, the second group of inputs of which is connected to the corresponding outputs of the frequency set block. One of the outputs of the frequency dialing unit is connected via a coarse frequency setting unit to the first input of a tunable generator, the second input of which is connected to the output of a reversible step voltage generator, and the output is connected to the second input of the first key.

The known device does not have high reliability in operation.

The purpose of the invention is to accelerate the configuration process.

The goal is achieved by the fact that the output of the frequency divider is connected to the first input of the reversible step voltage generator through a second key, and the first and second outputs of the D / A converter are connected to the corresponding second inputs of the second key and the reversible step voltage generator.

The drawing shows a functional diagram of the frequency synthesizer.

In the synthesizer, the reference generator 1 is connected via frequency divider 2 to the input of the first key 3, the output of which is connected to the input of counter 4. The second input of key 3 is supplied with voltage from the output of the tunable generator 5. The outputs of counter 4 are connected to one group of inputs of the D / A converter (DAC) 6, and the number of outputs of the counter 4 is equal to the number of inputs in the DAC group. The second group of inputs of the DAC is connected to the outputs of the block 7 frequency dial,

the number of which is also equal to the number of inputs of the DIC in the group. At block 7, the desired frequency is set using the controls. This value in encoded digital form is characterized by the state of the output of block 7 (for example, the absence or presence of voltage at the outputs). It is essential that the code on the output buses of block 7 corresponds to the code at the outputs of counter 4.

The DAC has two outputs, a "moan and a" reverse, which are connected to the second input of the key 8 and to the second input of the reversible generator 9 of the step voltage (GOS), respectively. The start signal is supplied to the first input of the GOS 9 from the output of the frequency divider 2 through the key 8. The output of the GOS 9 is connected to the control input of the generator 5. In addition, a coarse frequency control unit 10 connected to the generator 5 is controlled via a circuit

output unit 7 set of frequencies.

The synthesizer works as follows.

In block 7 of the frequency set, the desired frequency value is set. The frequency code is fed to a coarse frequency setting unit, where an analog value of voltage, resistance or other physical parameter is formed, with the help of which a coarse tuning of the generator 5 is performed. The voltage from the output of the generator 5 is fed to the signal input of the switch 3. To the control input 1 of 3 arrives pulses calibrated by duration. These pulses are generated using reference oscillator 1 and frequency divider 2. As a result, the key 3 is opened for the time interval during which the output voltage of the generator 5 is fed to the counter 4 frequencies. At each counting cycle, the state of the memory elements of the counter 4 reflects the current value of the frequency of the generator 5.

The value of the frequency from the outputs of counter 4 in an encoded form is fed to one group of inputs of the DAC 6. The second code of the inputs of the DAC is supplied with a frequency code, the value of which is set on the frequency set block 7.

D / A converter 6 converts the discrete state of input wiring to analog form. The frequency of the generator 5 is controlled by a reverse voltage generator 9 of a step voltage, which is triggered by the leading edge of a measuring pulse through a public key 8. At the output, the voltage of the gene is changed in steps (steps), therefore the generator 5 is controlled by this voltage It is also produced in jumps. The magnitude of the step is chosen so that the generator's adjustment margin is smaller (by 20–40%) than the counter meter.

Thus, for each counting cycle, the generator is rebuilt by almost the metering cost of the counter.

If the oscillator frequency, set using the coarse frequency setting unit 10, below the set value, the voltage from the DAC output controlling the reversal of the hcn 9, acts in such a way that the frequency of the oscillator 5 increases. After each counting cycle, the oscillator frequency is shifted by one turn, reflecting the oscillator frequency to the specified value. Finally, after the next rung, the frequency of the oscillator coincides with the set, up to the price of dividing the counter. From this moment on, the start-up pulses cease to arrive at the input of the GOS. The output voltage does not change. Generator 5 appears tuned.

Subject invention

A frequency synthesizer containing a series-connected reference oscillator, a frequency divider, a first key and a frequency counter, the outputs of which are connected to the first group of inputs of a D / A converter, the second group of inputs of which are connected to the corresponding outputs of the frequency set unit, one of the outputs of which is through a coarse-mounted unit the frequency is connected to the first input of an uninterruptible generator, the second input of which is connected to the output of a reversible step voltage generator, and the output is connected to the second the first switch, characterized in that, in order to speed up the tuning process, the output of the frequency divider is connected to the first input of the reversible step voltage generator via a second key, and the first and second outputs of the digital-analog converter are connected to the corresponding second inputs of the second key and the reverse generator step voltage.