JP3129720B2 - Monolithic microwave phase shifter - Google Patents

Description

Description of the Invention (Object of the Invention) (Field of Industrial Application) The present invention relates to an improvement of a monolithic microwave phase shifter.

(Prior art) In recent years, gallium arsenide (Ga)
Monolithic microwave integrated circuit (MMIC) technology that integrates semiconductor elements such as input / output matching circuits and field-effect transistors (FETs) on a semiconductor substrate such as As Tend to be widely used. For example, phase shifters using the MMIC technology are widely used in phased array antennas and the like, and downsizing of devices such as antennas has been realized.

7 and 8 are circuit diagrams of a conventional monolithic microwave phase shifter. However, the bias supply circuit is omitted.

FIG. 7 is a circuit diagram showing a monolithic microwave phase shifter of a loaded line type. A 1/4 wavelength distributed constant line 3 is connected between input and output terminals 1 and 2 of the microwave. The drain terminals 51a and 52a of the switching FETs 51 and 52 of the common source type via the matching distributed constant lines 41 and 42
Is connected.

The control signal Q is applied to each of the gate terminals 51b and 52b of the FETs 51 and 52.
The control terminals 6 to which c is supplied are commonly connected. With the circuit configuration shown in FIG. 7, the two FETs 51 and 52 can be simultaneously switched on or off by the control signal Qc to change the passing phase of the input microwave signal to obtain a desired phase shift amount. it can. Although such a phase shifter has good designability, it has a drawback that the chip size becomes large because the distributed constant line 3 of 1/4 wavelength is used. For example, when a phase shifter for the C band (approximately 5000 MHz band) is configured, the chip size is as large as about 2 × 2 mm per bit.

FIG. 8 is a circuit diagram showing a vector synthesis type monolithic microwave phase shifter. The input microwave signal from the input / output terminal 1 is divided into three 90-degree power dividers 71a, 71b, 71c.
Are distributed to signals having a phase difference of 90 degrees from each other, and supplied to variable gain amplifiers 72a, 72b, 72c, 72d, respectively. Each of these variable gain amplifiers 72a to 72d is appropriately amplified and controlled by signals from the control terminals 6a, 6b, 6c, and 6d, and then two power combiners.
It is derived from output terminal 2 via 73a, 73b and in-phase power combiner 74.

Each of the power dividers 71a to 71c, the power combiners 73a and 73b, and the power combiner 74 is basically configured using a 1/4 wavelength distributed constant line.

In this phase shifter, the amplification of each signal after distribution is controlled by the control terminal 6a.
6d, the passing phase of the synthesized signal is changed to obtain a desired phase shift amount. In such a vector combining type phase shifter, since the phase shift amount is determined only by the magnitude of the amplitude of the signal after distribution, the phase shift amount can be set arbitrarily and the setting accuracy is high. However, this phase shifter also requires a total of six power dividers / combiners based on a 1/4 wavelength distributed constant line, so that the chip size is large as in the case of the loaded line type phase shifter. There was a disadvantage.

(Problems to be Solved by the Invention) As described above, the conventional monolithic microwave phase shifter has a large chip size and cannot always be said to utilize the MMIC technology.

Accordingly, an object of the present invention is to provide a compact monolithic microwave phase shifter which eliminates such disadvantages.

[Configuration of the invention]

(Means for Solving the Problems) The present invention provides a monolithic microwave phase shifter formed on a semiconductor substrate, and a source grounded field effect transistor having a gate terminal and a drain terminal as input / output terminals, respectively. An admittance value is set in advance, and a plurality of two-terminal circuits are selectively switched and connected between the gate terminal and the drain terminal.

(Operation) The variable phase shift amount of the monolithic microwave phase shifter according to the present invention can be obtained by connecting a two-terminal circuit between the input and output terminals and determining the feedback circuit determined by the admittance value of the two-terminal circuit. This is based on a change in the amount of passing phase.
Therefore, since the two-terminal circuit can be constituted by lumped elements, the chip size can be significantly reduced as compared with the conventional phase shifter using a quarter-wavelength distributed constant line.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In the following drawings, the bias supply circuit is omitted.

FIG. 1 is a circuit diagram showing the operation principle of a monolithic microwave phase shifter according to the present invention.

That is, the phase shifter of the present invention has an input / output terminal for a microwave signal.
1,2 gate terminal 5b of the respective source grounded form FET 5, is connected to the drain terminal 5a, between the gate and drain terminals of FET5 (5b-5a), admittance value by the control signal Q _C from the control terminal 6 Is connected to a two-terminal circuit 8 that changes. Therefore, the two-terminal circuit 8 has input / output terminals
A feedback circuit is connected between the terminals 1 and 2 and the feedback amount is changed by the control signal Qc from the control terminal 6.

The operation principle of the phase shifter shown in FIG. 1 will be described with reference to an equivalent circuit shown in FIG.

That is, in FIG. 2, Rg is the gate resistance of FET5, Cgs
Is also the gate capacitance, gm is also the transconductance,
Zd also indicates the drain impedance, and the admittance value of the two-terminal circuit 8 is Y. Here, input terminal 1
If the input signal V1 is applied to and the output signal V2 is taken out from the output terminal 2, the phase difference θ between V2 and V1 (passing phase)
Is represented by the following equation (1).

θ = arg {[1 / (1 / Zd + Y)] * [Y−gm / (1 + jωCgsRg)]} (1) where ω represents the angular frequency of the input signal.

Thus, for example, when the case of | V2 / V1 | = 1 is considered, the admittance value Y of the two-terminal circuit 8 is expressed by the following equation (2).

| Y − (− 1 / Zd) | = | Y−gm / (1 + jωCgsRg) |
(2) The admittance value Y of the two-terminal circuit 8 that satisfies the expression (2) is represented by an admittance plane as shown in FIG. In FIG. 3, the admittance value Y of the two-terminal circuit 8 is on a vertical bisector C of a line connecting the point A of −1 / Zd and the point B of gm / (1 + jωCgsRg), θ
Is expressed as the apex angle of an isosceles triangle formed by points A and B having Y as a vertex. If the value of the admittance Y is appropriately selected at a position on the straight line C, the passing phase difference θ can be set arbitrarily. Therefore, by changing the admittance value Y of the two-terminal circuit 8 on the straight line C by the control signal, a phase shifter in which only the passing phase difference θ has a desired phase shift amount can be configured. Since the two-terminal circuit 8 can be formed in a small size by separately combining an FET, a lumped element, and the like, it does not greatly affect the chip size on which the FET 5 is formed. The third
In the figure, the case where | V2 / V1 | = 1 is described, but | V2 / V
Even if 1 | is set to any other value, a phase shifter can be similarly configured.

FIG. 4 is a circuit diagram showing an embodiment of the monolithic microwave phase shifter according to the present invention. The feedback circuit includes a plurality of two-terminal circuits 81, 82, 83,... 8N each having a different admittance value Y.
Are arranged in parallel, and these two-terminal circuits 81 to 8N are selectively switched and connected between the gate and drain terminals (5a to 5b) of the FET 5 by a control signal Qc from the control terminal 6.

As a result, by selecting an appropriate two-terminal circuit according to the control signal Qc from the control terminal 6, an arbitrary feedback admittance amount can be selected. Accordingly, the phase shifter can be configured with a small chip size in which the FET 5 is incorporated.

According to the above embodiment, the phase difference θ of the feedback circuit formed by the two-terminal circuit 8 is used, and
Since a circuit element requiring a large size and shape such as a wavelength distribution constant line is not used, the circuit can be downsized.

The passing phase difference θ by the feedback circuit is easily affected by the load impedance. Therefore, an impedance matching circuit can be added to each of the input and output sides to reduce the influence.

FIG. 5 is a circuit diagram showing the operation principle of a monolithic microwave phase shifter in which an impedance matching circuit is added to each of the input and output sides.

That is, FIG. 5 shows a circuit configuration shown in FIG. 1, in which an input terminal 1 has an impedance matching circuit formed by a grounded-gate FET 91, and an output terminal 2 has a grounded-drain FET 9.
The phase shifter is constructed by adding impedance matching circuits according to 2 respectively.

FIG. 6 is a circuit diagram showing another embodiment of the present invention utilizing the operation principle of FIG.
入 出力 8N input / output sides are connected to impedance matching circuits of grounded gate type FETs 911 to 91N and grounded drain type FETs 921 to 92N, respectively, and a feedback circuit including these impedance matching circuits is selected by a control signal from the control terminal 6. And a desired passing phase difference θ is obtained.

As described above, the monolithic microwave phase shifter according to the present invention can be used even if a new impedance matching circuit is added in the phase shifter.
Therefore, the chip size of the entire phase shifter can be significantly reduced. Incidentally, in the conventional loaded line type phase shifter in the C band, the chip size is about 2 × 2 mm per bit. However, according to the present invention, the size can be reduced to about 0.3 × 0.5 mm. The effect can be obtained.

〔The invention's effect〕

As described above, according to the present invention, it is possible to provide a monolithic microwave phase shifter having a small chip size, and the effect obtained in practical use is large. Further, since the adjustment of the phase shift amount is performed by switching the two-terminal circuit, the size can be reduced, and the adjustment of the phase shift amount is easy.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing the operation principle of a monolithic microwave phase shifter according to the present invention, FIG. 2 is an equivalent circuit diagram of the phase shifter shown in FIG. 1, and FIG. 3 is a phase shifter shown in FIG. FIG. 4 is a circuit diagram showing an embodiment of a monolithic microwave phase shifter according to the present invention, and FIGS. 5 and 6 are other phase shifters according to the present invention. Circuit configuration diagram showing the operation principle of the device and the embodiment,
7 and 8 are circuit diagrams each showing a conventional monolithic microwave phase shifter. 1 ... input terminal, 2 ... output terminal, 5 ... field effect transistor (FET), 6 ... control terminal, 8 ... two-terminal circuit.

Claims (1)

(57) [Claims] 1. A monolithic microwave phase shifter formed on a semiconductor substrate, wherein a grounded source field-effect transistor having a gate terminal and a drain terminal as input / output terminals, respectively, and admittance values thereof are set in advance. A monolithic microwave phase shifter comprising: a plurality of two-terminal circuits that are selectively switched and connected between a gate terminal and the drain terminal.