JPH0141230Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a phase shifter in a low frequency amplifier.

Conventionally, when trying to construct a phase shifter with phase characteristics ranging from 0° to 360° on the frequency axis and a constant gain with respect to frequency, the phase shifter 1 with the characteristics as shown in Figure 1 and the phase shifter 1 with the characteristics as shown in Figure 2 were constructed. It was necessary to form a two-stage series of phase shifters 2 having characteristics as shown in FIG.

By doing this, the phase shifter 1
By further shifting the phase of the 180° phase-shifted signal by 180° by the phase shifter 2, an output with characteristics as shown in FIG. 4 is obtained at the output terminal OUT.

Since the conventional phase shifter is constructed as described above, in order to obtain the necessary characteristics, the number of stages must be stacked, which has the disadvantage that the number of active elements and passive elements increases.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional method, and the phase difference between the input signal and the output signal changes from 0° to 180° once on the frequency axis, and then returns to 0° again. It is an object of the present invention to provide a phase shifter in which the gain is 1 regardless of frequency.

Hereinafter, embodiments of the phase shifter of this invention will be described based on the drawings. FIG. 5 is a circuit diagram showing the configuration of one embodiment. In this figure 5, 11
is a transistor. The base of transistor 11 is connected to input terminal IN via capacitor 12.

The collector of the transistor 11 is connected to the power supply (+)V through a resistor 13, and the emitter is connected to the power supply (-)V through a resistor 14. The base of the transistor 11 is connected to the power supply (+)V through a resistor 15 and to the power supply (-)V through a resistor 16.
Resistors 13 and 14 are gain setting resistors, and resistors 15 and 16 are bias resistors.

The collector of transistor 11 is capacitor 17
is connected to the output terminal OUT via a resistor 18 and a capacitor 19. The emitter of the transistor 11 is connected via a resistor 20 to a connection point between a capacitor 17 and a resistor 18, and is also connected via a resistor 21 and a capacitor 22 to a connection point between a resistor 18 and a capacitor 19.

The capacitor 17 is a capacitor for setting a low frequency time constant, and the resistor 20 is also a resistor for setting a low frequency time constant. Further, the resistor 18 is a resistor for setting a high frequency time constant, and the capacitor 22 is also a capacitor for setting a high frequency time constant.

Note that the resistor 21 is a resistor for high-frequency gain correction, and the capacitor 19 is an electrolytic capacitor.

Next, the operation of the phase shifter of this invention constructed as described above will be explained with reference to the circuit shown in FIG. This FIG. 6 is a circuit diagram for explaining the operation of the phase shifter of FIG. 5, and in this FIG. 6, the same parts as those in FIG. 5 are given the same reference numerals.

Furthermore, T1 and T2 are input terminals, respectively.
A case is shown in which a signal -Ae is applied to the input terminal T1, and a signal e is applied to the input terminal T2. Further, an output signal is obtained from the terminal T3, and the output from the terminal T3 is taken out from the connection point between the resistor 18 and the capacitor 19 in FIG. 5 as the output terminal T3.

In FIG. 6, the input terminal T of the network consisting of capacitors 17, 22 and resistors 20, 18
When signals having mutually opposite phases and having an absolute value ratio of A are added to T1 and T2, a signal having a phase shift characteristic as shown in FIG. 7 is outputted to the output terminal T3.

At this time, the gain can be made constant by selecting an appropriate value A. Therefore, a phase shifter having the characteristics shown in FIG. 7 can be constructed.

In the above embodiment, as shown in FIG. 5, the transistor 11 is composed of a single transistor, but as shown in FIG. A similar effect can be obtained by using .

In addition, in FIG. 7, capacitors 17, 22,
+Ae is applied to the input terminal T1 of the network constituted by the resistors 18 and 20, and -Ae is applied to the input terminal T2 of the network.
When e is input, characteristics as shown in FIG. 8 are obtained.

In FIG. 5, this corresponds to switching the collector side and emitter side in connection to the transistor 11 of the network. In this case, if the gain with respect to frequency is kept constant, the gain in the circuit using the transistor 11 will be negative.

As described above, according to the phase shifter of this invention, the first input terminal is connected to the output terminal via the first capacitor and the resistor, and the second input terminal is connected to the output terminal via the second resistor. It is connected to the connection point between the first capacitor and the first resistor, and is also connected to the output terminal via the second capacitor, and the phase is 180 degrees different between the first and second input terminals, and a predetermined amplitude ratio is set. This has the advantage that the circuit is simpler than the conventional one, and the range in which the phase shift characteristic can be varied is very wide.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional phase shifter, Figures 2 and 3 are characteristic diagrams of each phase shifter in Figure 1, and Figure 4 is obtained by the phase shifter in Figure 1. 5 is a circuit diagram showing an embodiment of the phase shifter of this invention, FIG. 6 is a circuit diagram for explaining the operation of the phase shifter of FIG. 5, and FIG. 7 is a diagram of the phase characteristics of the output. FIG. 5 is a phase characteristic diagram obtained by the phase shifter, and FIG. 8 is a phase characteristic diagram of another embodiment of the phase shifter of this invention. 11...Transistor, 12, 17, 19, 2
2... Capacitor, 13-16, 18, 21...
Resistor, IN, T1, T2...Input terminal, OUT, T
3...Output terminal.

Claims (1)

[Claims for Utility Model Registration] A first capacitor having one end connected to a first input terminal, a first resistor connected between the other end of the first capacitor and the output terminal, and a second capacitor having one end connected to the first input terminal. a second resistor connected between the input terminal and the other end of the first capacitor; and a second capacitor connected between the second input terminal and the output terminal, The two input terminals are in phase with each other.
A phase shifter characterized by applying signals that differ by 180 degrees and have a predetermined amplitude ratio.