SU919041A1 - Frequency converter - Google Patents

Description

one

The invention relates to radio engineering and can be used in radio receiving and radio measuring technology.

Known balanced frequency converters containing the input source, source, local oscillator, input divider (differential transformer, directional coupler, quadrature bridge), converting elements (transistors, lamps, diodes) i intermediate frequency filters, adder (or subtractor) intermediate frequency ( differential transformer, resonant contourX, low pass filter, etc. l.

Compared to conventional single-phase frequency converters, a balanced frequency converter has approximately twice the dynamic range of the input signal, since the power of the input signal is divided between the two arms of the converter.

The dynamic range of known balanced frequency converters is often insufficient and can be increased in known devices only through the use of powerful transducer elements and an increase in the power of the local oscillator, which, however, inevitably leads to an increase in the noise figure and, consequently, the sensitivity of radio receivers, Warhead and microwave ranges.

The closest to the present invention is a frequency converter containing an input-signal power divider, the first mixer of which is connected in series with the first mixer, the first delay line and the adder, the second delay line whose input is connected to the second output of the input signal power divider, the second mixer,

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output KOTCiporo soy /; frost with apyi named input of the adder, and the local oscillator, output i OTOpoio is connected to the heterodyne inputs of the first and second mixers 2.

The lack of a known converter is the low dingomic range of the input signal.

The purpose of the invention is to observe the dynamic range.

The goal is achieved by the fact that. to the frequency converter containing the power divider of the input signal, the first output of which is connected in series with the first mixer, the first delay line and the adder, the second delay line whose input is connected to the second output of the input signal power divider, the second mixer whose output is connected with another input of the adder, and a local oscillator, the output of which is connected to the heterodyne inputs of the first and second mixers, between the output of the first mixer and the cable input of the second mixer, enter O) 1 pos Consequently, the third mixer and subtractor are connected to another input connected to the output of the second delay line, while the heterodyne input of the third mixer is connected to the output of the local oscillator, and C y where C and Cj are the transmission coefficients of the input signal power divider respectively at the first and BTODOMV outputs.

The drawing shows the CTDVKTVD on the proposed frequency diagram.

The frequency converter contains the divider 1 of the input power, the first line 2 of the signal, the pitch mixer 3, the second mixer 4, the adder 5, the local oscillator 6, the third mixer 7, the second delay line 8 and the subtractor 9.

The frequency converter works as follows.

Suppose that the first mixer 3 and the second mixer 4 lower the frequency of the input signal. In this case, the third mixer 7 must be boost. The input signal goes to the output in three ways. The first way is the first output of the divider I, the first mixer 3, the first line 2 delays adder 5, the second way is the first mixer 3, the third mixer 7, the subtractor 9, the second mixer 4, sum14

Mat 5, IpeTHij path - the second output of the divider 1, the second delay L 8 and 8, the subtractor 9, the second mixer 4, the adder 5,

To simplify the recording, but without losing obi; 1, we take the transfer factors of the delay lines, the subtractor and the adder equal in modulus to one, and the gain (or transfer) coefficients for the voltage of the mixers are denoted by K., K. and Kj, respectively. When compensating for the delay lines of the group lag time and its unevenness, which the mixers and filter add, we have for the gain over the voltage of the device as a whole.

K-iVkv

T / DG f)

The relation () is obtained under the condition of equal division of the signal by the divisor 1 (the inequality of the signal is taken into account below) „

With the balance of the device, i.e. under the conditions

Kj - and (or) K, - (I)

  Ki

N we have j. . ,

, - (3)

L

From () it also follows that

4jil K

Lui

()

4.0 K;

Kg. s

Claims (2)

i.e., the relative error of the gain of the frequency converter B is generally a second order of smallness value, provided that the third mixer has - 0. From relations (2) to (4) it follows that to obtain the gain from the frequency converter as a whole so that the first and second mixers have K 1 and, i.e. the first and second mixers should be performed either on active transducer elements (pampas, transistors, etc.), or on naccHBtibix transducer elements, for example, on Schottky barrier diodes, but with the addition of an intermediate frequency amplifier; the third mixer 7 must have 1, i.e. (It can be performed either on diodes, for example, Schottky barrier diodes, or (3o per actin} 1st transducer elements, but with the addition of an attenuator of a corresponding wellness. Use the third diode mix. 7 Ples 59 is preferable because it is more stable in cpaBiieHHij for example, with transistor capacitors, and, therefore, condition 0 is more easily achieved. In addition, the diode mixer introduces much less intrinsic noise. Increasing the dynamic range without increasing the noise figure can be qualitatively shown as follows. The mixer mixer 3 is made, for example, on an average power transistor, and the second mixer 4 is built on a low-power, low-noise transistor.In this case, the first mixer 3 will have a larger dynamic range but also a higher noise figure compared to the second mixer 4. It is easy to see that with the balance, under the condition K K2,: t-) the intrinsic noise of the first mixer will be compensated, since the transmission coefficients for the balance of the circuit and the assumptions made from the output of the first mixer to the output of the entire device th and the second path are equal in magnitude and opposite in sign. Thus, the overall noise figure of the frequency converter will be determined by the low-noise second mixer 4. and the dynamic range by a relatively powerful first mixer 3. To obtain a small coefficient of the second mixer 4, It is necessary that the losses in the input circuit of the second mixture 4 be small, in other words, it is necessary for divider 1 to transmit almost the entire signal to the input of the second mixer 4. For example, if a directional coupler with a transient attenuation of 10 dB is used as divider 1 with respect to To the first output, the noise ratio of the second mixer 4 ksc is increased by 0.4 dB. A quantitative analysis of the proposed device leads to the following relationship. The voltage gain in the balance is P - - n YH-C-; (5) where C is the transfer coefficient of the divider 1 at its first output. The coefficient of the whole device is 6; uiaHce 1 - C, 6 It should be noted that by reducing the transfer ratio of the divider 1 to the input of the first mixer 3, the input signal of the entire device without increasing the noise figure increases by about 10 1 ds (dB) even at the same dynamic ranges of the first and second mixers. The proposed device allows to significantly increase the dynamic Kiifi range of frequency converters without increasing the noise figure, which increases the noise immunity of radio receivers and facilitates solving the problem of electromagnetic compatibility of radio engineering devices, Invention Frequency converter containing the power divider of the input signal, the first mixer of which is connected in series with the first mixer , the first delay line and the adder, the second delay line, whose input connected to the second output of the input power divider, the second mixer, the output of which is connected to another input of the adder and the local oscillator, the output of which is connected to the heterodyne inputs of the first and second mixers, characterized in that, in order to increase the dynamic range, between the output of the first mixer and the signal the input of the second mixer, entered in series the third mixer and the subtractor, the other input of which is connected to the output of the second delay line, while the heterodyne input of the third mixer connected to the output of the local oscillator, and C, C, where C and Cj are the transmission coefficients of the input signal power divider, respectively, on the first and second entrances. Sources of information taken into account in the examination 1. Distance communication. Ed. A.N.Zingerenko. M., St. Sizdat, 1970, p. 148. fig. 8.22. 2. Ls-eev B.P. Phase relations in radio engineering. M., Sv zizdat, 1959, p. 118, fig. 3-23, (prototype). / / / L /