SU1244783A1 - Double balanced modulator - Google Patents

Abstract

The invention relates to radio engineering. Non-linear distortion decreases with increasing coefficient. transfer. The device contains four transistors (T) 1-4 input transformer (Tr) 5, output Tr 6, driver of paraphase rectangular carrier frequency signals, voltage converter, into current (PNT) 8. The converted signal goes to the primary winding of TP 5 and c its secondary winding to emitters T 1,2 and. When on bases T 1., 4 acts positive, and on bases T 2,3 - negative. the half wave does not exist, the device is an amplifier with a common base at T 1.4. The phase of the signal at its output coincides with the phase at the input. When the carrier polarity is changed, T 2.3 already work and the phase of the signal at its output is opposite to the phase at the input. So The device performs the Y1 operation of the input signal on the coefficient. amplification and switching function, which achieves a two-way amplitude modulation at the carrier frequency with the suppression of the latter. In the device, the sum of the currents is always constant. Its value is given by PNT 8 and does not depend on the carrier level. 2 Il. € CO Input 5 8b / ho FIG.

Description

The invention relates to radio engineering, in particular, to frequency converters of weak electrical signals, and can be used in radio receiving, radio transmitting devices, telecommunications equipment with frequency multiplexing, frequency synthesizers, etc.

The purpose of the invention is to reduce non-linear distortion with increasing transmission coefficient.

Fig. 2 shows the structural electrical circuit of the proposed balanced modulator; Fig 2 - timing charts of his work.

The double balanced modulator contains the first, second, third, and fourth transistors 1–4, input 5 and output 6 transformers, driver 7 of paraphase: rectangular carrier frequency signals, driver 8 of the DC signal.

The double balanced modulator operates in the following way.

The converted signal is fed to the primary winding of the input transformer 5 and from the ends of the second winding to the emitters of transistors 1,2 and 3,4. At the moments when on the bases of transistors 1 and 4 is positive, and on the bases of transistors 2 and 3 is negative a half-wave carrier, a double balanced modulator is an amplifier with a common base on transistors 1 and 4, and the phase of the signal at its output coincides with the phase of the signal at its input, and when the polarity of the carrier changes to the opposite, the double balance modulator representsis the same amplifier with a common base, but transistors 2 and 3 already work in it, and the phase of the signal at its output takes on the value opposite to the phase of the signal at its input. Thus, the double balanced modulator performs the operation of multiplying the input signal by the gain of the push-pull amplifier with a common base and the switching function

H (t)

G when -O when

and

five

0

five

0

five

this achieves dual-band amplitude modulation at the carrier frequency with the latter suppressed.

In the proposed double balanced modulator, the sum of the currents is always constant and equal to 1, and the value of this current is set by the driver 8 and does not depend on the carrier level.

Fig. 2a is a voltage carrier voltage diagram in the presence of voltage supplied from a driver 8; Fig.25 is a diagram of the total current through transistors 1 and 4; and FIG. 2 is a diagram of the total current through transistors 2 and 3. It can be seen from the diagrams that the current in the load is zero at the points in time when the voltage of the carrier frequency crosses the zero line.

Claims (1)

Invention Formula Double balanced modulator containing 1 {first, second, third and; the fourth transistor, the paraphase rectangular carrier frequency driver, the first output of which is connected to the bases of the first and fourth transistors, and the second output to the bases of the second and third transistors, the input transformer, whose primary winding is the input of the signal being converted, the first output of the secondary winding which is connected to the emitters of the first and second 0 five the second transistor, with the emitters of the third and fourth transistors, and the output transformer, the first output of the primary winding of which is connected to the collectors of the first and third transistors, the second output - to the collectors of the second and fourth transistors, and the middle tap - with the output of one nz power supply busbars, characterized in that, in order to reduce non-linear distortions with increasing transmission coefficient, a direct current shaper is inputted into it, the input voltage of which is connected to The power supply voltage of the paraphase rectangular signal generator, carrier frequency ills, and their connection point is connected to another source of power supply, and the secondary 5 windings of the input transformer are provided with a middle tap that is connected to the DC signal conditioner. 0 Editor M.Tovtin Compiled by G. Zakharchenko Tehred N. Bonkalo Proofreader O. Lugov Order 3927/58 Circulation 816 Subscription VNIUSH USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 FIG. Z