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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Broadband phase shifters. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Radio amateur designer Broadband phase shifters (SF) are designed for linear transformation - "splitting" - of a low-frequency signal in order to obtain two signals with constant amplitude and phase shift (most often 90 degrees) in a wide frequency range. In amateur radio practice, such phase shifters are used in musical acoustics to obtain synthetic unisons and stereophony, in sound systems to suppress parasitic acoustic feedback. In the technical literature, broadband phase shifters are found under the names of a broadband quadrature filter and broadband difference circuits [1, 2]. In the same publications, methods for calculating such devices are presented. Initial parameters for calculation: frequency overlap ratio, required constant phase shift between signals (phase-difference characteristic) and the maximum allowable deviation (error) of this shift. The more stringent these requirements, the more complex the phase shifter circuit. You can find descriptions of various broadband phase shifters containing active elements (microcircuits). However, in practice, phase shifters on resistors and capacitors are most often used. Below we consider similar devices, assembled only on passive elements, as providing maximum reliability. An exception is the input phase splitter on one transistor, which provides power to the device with two antiphase signals of the same amplitude. If necessary, this active element can also be replaced by a low-frequency transformer with a low output impedance.
The phase shifter, the circuit of which is shown in fig. 1, provides a phase shift between the output signals of 90 degrees in the frequency band 50 ... 10000 Hz with an error of no more than 3 degrees. The voltage transfer coefficient of the phase shifter is approximately 0,4.
The diagram shows the standard values of the elements of the phase shifter, and in table. 1 - the exact values of the resistance of the resistors and the capacitance of the capacitors These elements must be selected with an accuracy of at least 1%. TKE capacitors should be no worse than M150. It is desirable to provide for the possibility of selection within a small range of resistors R10, R11 and capacitors C7, C8. The constant voltage across the resistors R10, R11, coming from the emitter and collector of the transistor VT1, can be used to set the mode of subsequent steps. In this case, the constant and variable components of the voltage must, of course, be separated. The need for the use and characteristics of filters that suppress the frequency components below and above the phase shifter band are determined for each specific case separately. The described broadband phase shifter (see Fig. 1) is used in a frequency spectrum shifter that implements spatial unison vibrato, also known as "two-point unison" [3]. The same publication gives recommendations on the use of such devices in musical acoustics. In table. Figure 2 shows the exact values of the resistance of the resistors and the capacitance of the capacitors of a more advanced phase shifter assembled according to the circuit in Figure 1. This phase shifter provides a phase shift of 90 degrees, in a frequency band of 200 ... 10000 Hz with an accuracy of about 1 degree. Elements must be selected with an accuracy of no worse than ±1%. and capacitors - to have a TKE no worse than the M150.
In some cases, it becomes necessary to use a broadband phase shifter with a phase shift of 120 degrees. On fig. 2 shows a diagram of a phase shifter that provides such a phase shift in the frequency band 200 ... 6800 Hz with an error of about 3 degrees. The standard values of the elements are indicated in the diagram, and the exact values \u3b\uXNUMXbof the resistance of resistors and capacitor capacitances are in Table. XNUMX. Requirements for radio elements are similar to those indicated above.
The third phase with a shift of 240 degrees is obtained by summing two signals of equal amplitude, shifted in phase by 120 degrees, and inverting the total voltage. The principle of obtaining a voltage with a phase shift of 240 degrees is illustrated by a vector diagram in fig. 3. Literature 1. Avramenko A. A., Galamichev Yu. P., Lanne A. A. Electric delay lines and phase shifters. - M. - Communication. 1973
Author: L. Korolev, Moscow; Publication: radioradar.net
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Comments on the article: Boris I really need a similar rotator for 120 degrees. for the HF range (0,3-3 MHz), and Avramenko's books, well, nowhere in the internet is there tttttuuuuu !!!!! at work it is necessary, not to indulge .... maybe someone will throw it in a personal?
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