SU1497719A1 - Variable phase shifter - Google Patents

Abstract

The invention relates to the measurement technique and m. applied in radio measuring devices. The purpose of the invention is to expand the frequency range. Adjustable phase shifter contains cond-p 3, variable resistor 4, operational amplifier 5. Two diodes 1 and 2 are inserted in the phase shifter. Due to the fact that the charging time of the cond 3, through diodes 1, 2 connected in parallel, does not depend on the input frequency signal in the working frequency range, the phase shift of the adjustable phase shifter does not depend on the frequency of the input signal in the working frequency range. 2 Il.

Description

FIG. one

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This invention relates to a measurement technique and can be applied in radio measuring devices.

The purpose of the invention is to expand the frequency range.

Fig. 1 shows an electrical functional diagram of the variable phase shifter; on - voltage plots, which reduce the operation of the device.

Adjustable phase shifter contains diodes 1 and 2, capacitor 3, variable resistor 4 and operational amplifier 5.

Adjustable phase shifter works as follows.

A sinusoidal voltage U is supplied to the input of the adjustable phase shifter, which through an adjustable

,

a voltage divider, made on a variable resistor 4, is fed to the inverting input of an operational amplifier (OU) 5 (). At the same time, the non-inverting input of the OU 5 receives a voltage and, which is shifted from the input voltage by the time determined by the charging time of the capacitor 3 through the open diode 1, with a positive input signal amplitude, and through the open diode 2 - with a negative value of the amplitude of the input signal, limited in amplitude by the magnitude of the diode cutoff voltage.

The capacitance value of the capacitor 3 is selected from the conditions:

Хр „- for the lower boundary frequency of the adjustable phase shifter (where R q g is the diode resistance in the closed state, and X sn is the reactance of the capacitor at the lower boundary frequency) i

for the upper cutoff frequency of the adjustable phase shifter (where R and, o is the diode resistance in the open state, and X

R ,,

R ,.

the capacitor at the upper cutoff frequency)

The operational amplifier operates in the comparator mode, therefore, when applied to the inverting input of the OU 5, it is adjustable in amplitude, and not to

15

20

25

thirty

35

about 40 45

Q Q is a rotating input of a sinusoidal input voltage that is phase-limited and amplitude-limited at moments of equal voltage at OU 5 inputs; OU 5 output signal is switched (Fig.2b, c), i.e., output pulse voltage is generated, which pulses have the form of the meander and are shifted in phase with respect to the input sinusoidal voltage by a phase angle greater than the charging time of the capacitor 3 and determined by the voltage amplitude at the output of the riept-name resistor AO

Due to the fact that the charging time of the capacitor 3 through the anti-parallel diodes 1 and 2 do not depend on the frequency of the input signal in the working frequency range, the phase shift of the adjustable phase shifter does not depend on the frequency of the input signal in the working frequency range

Claims (1)

Invention Formula An adjustable phase shifter containing an operational amplifier, whose output is an output of an adjustable phase shifter, a variable resistor, the first terminal of which is connected to a common bus, a capacitor, the first terminal of which is connected to a non-inverting input of an operational amplifier, characterized in that It has two diodes that are connected in anti-parallel between the second output of the variable resistor, which is the input of the variable phase shifter, and the non-inverting input about eratsionnogo amplifier inverting, input of which is connected to the middle terminal of a variable resistor and a second capacitor terminal connected to a common bus.