SU1383495A2 - Frequency divider with fractional division ratio - Google Patents

Description

(61) 1051729

(21) 4131058 / 24-21

(22) 08.10,86

(46) 03/23/88. Bul № 11

(72) M.A. Aksenov and V.Z. Irgibaev

(53) 621.374 (088.8)

(56) USSR Author's Certificate No. 1051729, cl. H 03 K 23/6, 07/06/81.

(54) THE DIVIDER OF FREQUENCY WITH A CROSSBAND Fission Factor

(57) The invention relates to the pulse technique and can be used in digital frequency synthesizers.

The accuracy of the device is increased as a result of applying the proposed circuit construction of a frequency divider, which contains a frequency divider 1 with a variable division factor, input bus 2, output bus 3, counter 4 pulses, converter 5 codes, bus 6 of the code of the fractional part of the division factor, adder 7 bus 8 the code of the integer part of the division factor. The device allows division by coefficients, the denominator of the fractional part of which could not be reduced to a common denominator equal to the value of the counter conversion factor of 4. 2 Il.

with

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figure 1

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oo 4; coke

S

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A: Excretion refers to a pulse; The technique is intended for use in digital frequency synthesizers and is an improvement on the known 1: 10 invention of the author. Ev, No. 1U51729.

The purpose of the invention is to show accuracy.

FIG. 1 shows the electrical I ka structured frequency divider circuit; in fig. 2 - electrical: functional divider often-; You, when the constant storing device is used as a code converter,: A frequency divider with a fractional dividing factor contains a frequency divider I 1 with a variable division factor I, the input of which is connected to I input bus 2, and the output frequency

bus 3 and with a countable input of the counter I 4 pulses, the outputs of which are connected to the first group of inputs of the converter of 5 codes, the second group of inputs of which are connected to bus 6 of the fractional part code of the division factor, the first output of the converter of 5 codes, is connected to the input of the adder 7, the group of inputs of which is connected to the bus 8 of the code of the integer part of the division coefficient I, the codes to the information inputs of the frequency divider 1 with a variable division factor, the second output of the converter 5 codes connected to the input of the installation of the counter 4 impulses all

The frequency divider works as follows.

When the divider 1 is filled with pulses coming from bus 2, a pulse is generated at its output, which arrives at bus 3 and at the counting input of counter 4. The initial installation code for divider 1 in the form of K or K + 1 is formed at the outputs of adder 7 The inputs from which bus 8 receives the code of the integer part of the device division factor (code K) "and the other input receives a logical 1 or logical O signal, which is generated by the converter 5. Each pulse on bus 3 changes the state of counter 4 from the outputs the counter status code of 4 pulses is taken, sec. - stupid to the lower address inputs of the converter 5. To the higher address inputs of which comes from the bus b the fractional part code of the coefficient de

five

0 5 0

0 s

0 5

laziness. Each address in converter 5 corresponds to a cell, one bit of which is responsible for generating a logical 1 or logical O signal arriving at the adder 7, and the other bit generating a signal for the initial installation of counter 4.

The cycle time of the device is determined by the conversion factor N of the counter 4 and is a variable value depending on the fractional values of the division factors of the device.

Thus, the proposed device allows division by coefficients, the denominator of the fractional part of which cannot be reduced to a common denominator equal to the value of the conversion factor N of counter 4 (in the known device). For example, using a pulse counter with a conversion factor of N 10 or N 16, using a 4-bit pulse counter in the known device, it is impossible to make an exact division into coefficients that have values of 1/3 in the fractional part. 2/3, 1/7, 2/7 and t, d., Which is achieved in the proposed device by setting the conversion factor of counter 4 to 3 or 7.

A higher division accuracy in the proposed device appears. at the same counter with the known, but insufficient, discharge 4. For example, when used in digital synthesizers, the frequencies executed using the same 4-bit pulse counters when divided by a factor of 3, T5 will have the following accuracy of division; for a known device with a conversion factor of N 16 pulse counter takes - I 2

with a ratio of 3 3.125. but for

the proposed device takes the coefficient 3

J 3,154, or Згтт-

, 143; For the N 10 conversion factor, for a known device, we get either 5 ,, 1, or 5.2, and for

one

the proposed device 3

3.154,

Claims (1)

Invention Formula Frequency divider with a fractional division factor for aut. St. K 1051729, different By the fact that, in order to improve the accuracy, the second output of the code converter is connected to the installation input of the counter IMULS. FIG. g