JPH02146810A - Phase shifter - Google Patents

Abstract

PURPOSE:To reduce the circuit scale per bit by connecting a FET of Schottky gate structure and an inductance in series and using a gate terminal of the FET as a switching control terminal. CONSTITUTION:A FET 11 of Schottky gate structure as a switch is replaced equivalently with a resistor of a small resistance when the FET is conductive, with a capacitor when the FET is not conductive. Thus, a phase is retarded when the FET 11 is conductive and the phase is advanced when the FET 11 is inactivated. The phase difference is taken to activate the circuit as a phase shifter. Since the capacitance when the FET is turned off depends on the gate width of the FET 11, a desired phase shift is obtained by selecting the gate width of the FET 11 as a proper value. Thus, no capacitor is required in terms of the circuit constitution and one switch control terminal/bit is required, then the circuit constitution is simplified and the circuit scale is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a phase shifter, and more particularly to a phase shifter using a field effect transistor (hereinafter referred to as MESFET) having a Schottky gate structure.

[Prior art] ME has traditionally been used as a phase shifter used in high frequency circuits, etc.
One using SFET is known.

FIG. 3 shows the basic circuit configuration of this phase shifter. This circuit corresponds to 1 bit, and has an inductor 3 and a capacitor 4 connected in parallel between input terminal 1 and output terminal 2.
and MESFETs 5 and 6 inserted between the inductor 3 and capacitor 4 and the input terminal 1, respectively.

The gates of MESFETs 5.6 are connected to switch control terminals 7, 8, respectively. A desired amount of phase shift can be obtained by, for example, selectively turning on the MESFETs 5.6 by switch control signals applied to these terminals 7 and 8.

[Problems to be Solved by the Invention] The conventional phase shifter described above requires a capacitor for each bit. However, this capacitor occupies a large area in an integrated circuit. Furthermore, since two switch control terminals are required for each bit, the circuit size increases as the number of bits increases.

The present invention has been made in view of such problems, and includes:
It is an object of the present invention to provide a phase shifter that has a simple circuit configuration and can occupy a sufficiently small area.

[Means for Solving the Problems] A phase shifter according to the present invention includes one MESFET,
One inductor is connected in series, one end of the series circuit is used as an input terminal, and the other end is used as an output terminal.
It has a configuration in which the gate electrode of ET is used as a switch control terminal.

[Function] The MESFET equivalently functions as a resistor in the ON state and as a capacitor in the OFF state. Therefore, according to the present invention, since the MESFET and the inductor are connected in series, when the MESFET is in an ON state, it becomes a series circuit of a resistor and an inductor, and when it is in an OFF state, it becomes a series circuit of a capacitor and an inductor. As a result, the latter phase advances. Follow, MESFET ON, O
By controlling the FF, operation as a phase shifter is realized.

In the present invention, a phase shifter is realized with one MESFET and one inductor, and a capacitor and multiple control terminals are not required. Therefore, the circuit scale per bit can be significantly reduced, and a circuit with a small occupation area can be realized. can get.

[Example] Next, an example of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an equivalent circuit diagram of the basic configuration (for 1 bit) of a phase shifter according to an embodiment of the present invention.

The drain of MESFET I 1 is connected to one end of an inductor 12, and the other end of the inductor 12 is connected to an input terminal 13'. The source of MESFET I 1 is connected to the output terminal 14 , and the gate is connected to the switch control terminal 15 .

In the above configuration, MESFETI as a switch
I is equivalently replaced by a small resistance in the ON state and a capacitor in the OFF state. Therefore, MESFET
When I1 is in the ON state, the phase is delayed, and when I1 is in the OFF state, the phase is advanced. By obtaining this phase difference, it can be operated as a phase shifter.

The capacitor capacity in the OFF state is determined by the gate width of MESFETll. For this reason, MESFETI
By selecting an appropriate value for the gate width of 1, a desired amount of phase shift can be obtained.

That is, the inductance of the inductor 12 and the signal source impedance are Z. , the center frequency is f. , where the desired amount of phase shift is φ, is given by the following equation.

The gate width of MESFETI1 is O of MESFETll.
The capacitance at FF is ((2πfo)2・L +2(2πf 0)ZO−tan(φ/2) ) −'
・Select a value that satisfies (2).

Next, as a specific operation example, a GaAs MESFET with a gate width of 1120 μm is used, and the inductance is set to 0.3.
3n) 2 designed with a center frequency of 9.1GH2 as I
Figure 2 shows the simulation results for a 2.5° bit phase shifter. As is clear from FIG. 2, within the ICl3 band, the phase shift error was +1.5° to -0.8°.

[Effects of the Invention] As explained above, the present invention makes use of the switching capacitance of MESFET to eliminate the need for a capacitor in the circuit configuration, and furthermore, it can eliminate the need for a single switch control terminal.
Since no bit/bitL is required, there is an effect that the circuit configuration is simplified.

[Brief explanation of the drawing]

Figure 1 is an equivalent circuit diagram of a phase shifter according to an embodiment of the present invention, Figure 2 is a characteristic diagram showing simulation results using the equivalent circuit, and Figure 3 is an equivalent circuit diagram of a conventional phase shifter. be. 3.12. Inductor, 4; Capacitor, 5°6.11
;MESFET, 7,8,15;Switch control terminal

Claims (1)

[Claims] (1) One field effect transistor with a Schottky gate structure and one inductor are connected in series, one end of the series circuit is used as an input terminal, the other end is used as an output terminal, and the field effect transistor A phase shifter characterized by using a gate as a switch control terminal.