JPH02172308A - Bias circuit for microwave oscillator - Google Patents

Abstract

PURPOSE:To supply only a DC bias voltage to an active element by applying the DC bias voltage from a position where a line is short-circuited as to a microwave signal of a fundamental wave in a bias circuit provided on a half way of a microstrip line. CONSTITUTION:A bias circuit 20 comprising end open stubs 20-1, 20-2 having a length of lambda0/8, lambda0/4 in an orthogonal direction and having a length of lambda0/8, lambda0/4 in a parallel direction is connected to a midway of a microstrip line 10. Thus, the fundamental wave is short-circuited at a point 21 apart by a distance of lambda0/4 from the open end of the termination open stub 20-2 and a 2nd harmonic wave is short-circuited at a point 22 from a distance of lambda0/8 from the open end of the termination open stub 20-1. Moreover, when viewing the bias circuit 20 from an input terminal 100 of the microstrip line 10, both the oscillated output in the fundamental and the 2nd harmonic waves is opened in its input terminal 23. Thus, only a DC bias voltage is supplied to an active element of a microwave oscillator from a bias point 21 separately.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a bias circuit for a microwave oscillator that supplies a DC bias voltage to active elements such as FETs constituting the microwave oscillator.

(Prior Art) In a conventional bias circuit for a microwave oscillator, as shown in FIG. A microwave oscillator is generated by applying a DC bias voltage to a point 41 (bias point) on an open-ended stub 40 attached to the microstrip line 10 and formed of an abbreviated microstrip line. It was supplying the active elements of

This open-ended stub 40 has an open end so that the impedance to the fundamental wave (frequency f0) is infinite, that is, it is in an open state when viewed from the attachment point 42 (actually, this point is a reference) on the strip line 10. The distance from the attachment point 42 of the microstrip line 1.0 to the wavelength of the fundamental wave is λ. Then λ. The pattern was formed to have a length of /2.

Further, the bias point 41 to which the DC bias voltage is applied is approximately λ from the open end. /4 distance, that is, a point at which a short circuit occurs for the oscillation output of the fundamental wave is selected.

(Problems to be Solved by the Invention) As mentioned above, the bias circuit of the conventional microwave oscillator is configured so as not to affect the active elements of the microwave oscillator to which the DC bias voltage is supplied only for the oscillation output of the fundamental wave. Therefore, when a second harmonic (2fO) signal is transmitted on the microstrip line 10, the following problems occur.

That is, for the second harmonic wave, the impedance of the branch point 42 with the microstrip line 0 changes due to a change in the impedance of the bias point 41, which adversely affects the operation of the active element.

Furthermore, the output end side 101 of the microstrip line 10
However, there was a problem in that it was not possible to obtain a double wave signal of a predetermined level.

The present invention was made in view of these circumstances, and
The DC bias voltage and microwave signal transmitted on the same microstrip line are separated, and only the microwave signal is transmitted to the output end of the microstrip line.
It is an object of the present invention to provide a bias circuit for a microwave oscillator that can supply only a DC bias voltage to the active element.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides frequency f (wavelength λ
one open-ended stub branched and connected to the microstrip line through which the microwave signal of 0) and the DC bias voltage for driving the micro oscillator are transmitted together, and from the open end of the two open-ended stubs. The length to the branch point with the microstrip line is λ. /2 in a bias circuit with λ on the - two open-ended stubs. /2n (n is an integer of 2 or more) with another open terminal stub, and connect the DC bias voltage application point to the line or short circuit for the microwave signal of the fundamental wave (frequency f0). approximately λ from the open end of the two open-ended stubs.

It is characterized by being provided at the /4 position.

(Operation) Along with the microwave signal, a DC bias voltage is transmitted on a common microstrip line. Then, substantially only the DC bias voltage is supplied from a predetermined bias point to the active element of the microwave oscillator by a bypass circuit provided in the middle of the microstrip line.

On the other hand, the microwave signal is prevented from flowing into the bias point by the bias circuit, and is output to the output end of the microstrip line.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of essential parts of an embodiment of a bias circuit for a microwave oscillator according to the present invention. In the figure, there is a microstrip line 10 in the middle of the microstrip line O through which the microwave signal is transmitted.
parallel to λ, respectively. /8 (λ is the wavelength of the fundamental wave), λ
. /4 in the direction perpendicular to microstrip line]0, respectively. /8. open-ended stub 201.20-2 having a length of λ, /4 (232] length)
A bias circuit 20 consisting of the following is connected.

In the above configuration, a fundamental wave (frequency f0) and a double wave (frequency 2 fo ) of the microwave signal are input to the microstrip line 10 from the input end side 100 of the microstrip line 10. Then, regarding the fundamental wave, λ from the open end of the open-ended stub 20-2. A short circuit occurs at a point 21 located at a distance of /4, and the second harmonic is λ from the open end of the open termination stub 201. Point 2 at a distance of /8
2 causes a short circuit.

Furthermore, when viewing the bias circuit 20 from the input end 100 of the microstrip line 0, the input end 23 is in an open state for both the fundamental wave and the second harmonic oscillation output. Therefore, if point 21 is selected as the bias point, the impedance state will not change, so only the DC bias voltage can be supplied separately from bias point 21 to the active elements of the microwave oscillator. A fundamental wave and a second harmonic microwave signal are sent to the side]0].

FIG. 2 shows the structure of another embodiment of the invention. In this embodiment, the frequency is f0 (fundamental wave) and 2f.

(n-1)fo, nfo (n is an integer of 2 or more)
0 from the input end 1-00 to the output end 101, the oscillation output is configured to prevent these oscillation outputs from flowing into the bias circuit 30 that supplies a DC bias voltage.

That is, the input terminal 31 of the bias circuit 30 has a frequency fo
, -, (n 1) fo, nf0 (n is an integer greater than or equal to 2) microstrip line]
λ in parallel to the microstrip line 10 so that the impedance seen from the input end 31 (actually, this point is the base) is infinite. /4n, λ. /4(n-1
), ..., λ.

/4, and the distance to the line 10 in the direction orthogonal to this microstrip line 10 is λ. /
4n λ. /4(n-1), ·, λ. A plurality of open-ended stubs 30-], ]30-2.
-, 30- are provided on the microstrip line 10.

In this bias circuit 30, the terminal open stub 301.30
-2. ..., λ from the open end at 30-n. /
4n, λ. /4(n-1), ・,λ. /4 at points 32n, 32n-1, ..., 32, the frequency n
fo , (n 1) fo , -1f. Regarding the oscillation output, the transmission line becomes short-circuited. Therefore, it is possible to take out only the DC bias voltage using point 321 as a bias point and supply it to the active element of the microwave oscillator. Also, the output end side 10 of the microstrip line 10],
has a frequency f. .

Oscillation outputs of (no,)fo, . . . , nfo are obtained.

In each of the above-described embodiments, a plurality of oval-shaped open end stubs are connected, but the present invention is not limited to this and can be formed into any shape. That is, the length from the open end of the open-ended stub to the branch point may be set to a predetermined length.

(Effects of the Invention) As explained below, the present invention prevents the inflow of microwave signals into the middle of the microstrip line that transmits microwave signals of a predetermined frequency, and allows only the DC bias voltage to pass through. In addition to providing a bias circuit to control the fundamental microwave signal in the bias circuit, the DC bias voltage is applied from the position where the line is short-circuited, so the DC bias voltage and the microwave signal are separated and the microwave signal is Only a microwave signal can be transmitted to the output end of the strip line, and only a DC bias voltage can be supplied to the active element.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of the main parts of one embodiment of the bias circuit of a microwave oscillator according to the present invention, FIG. 2 is a circuit diagram showing the configuration of another embodiment of the present invention, and FIG. FIG. 2 is a circuit diagram showing the configuration of a bias circuit of a conventional microwave oscillator. 10...Microstrip line 20.30...Bias circuit 21.321...Bias point 100...Input end side 101...Output end side

Claims (1)

[Claims] One open-ended stub branched and connected to a microstrip line through which a microwave signal of frequency f_0 (wavelength λ_0) and a DC bias voltage for driving a micro oscillator are transmitted together, the one open-ended stub In a bias circuit in which the length from the open end of the stub to the branch point with the microstrip line is λ_0/2, the one terminal open stub has a length λ_0/2n (n is an integer of 2 or more). , and the point at which the DC bias voltage is taken out is approximately λ_0 from the open end of the one open-ended stub where the line is short-circuited for the microwave signal of the fundamental wave (frequency f_0).
A bias circuit for a microwave oscillator, characterized in that it is provided at a position of /4.