JPH0441616Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a mounting structure for a high-frequency, low-noise transistor used as an amplification element for microwave band signals.

(Prior technology) Bipolar low-noise transistors and GaAs low-noise transistors with low noise figure (NF) and high gain are used as amplification elements to amplify microwave band signals.
High-frequency, low-noise transistors such as FETs are used. FIGS. 7 and 8 show an example of a conventional mounting structure for a high frequency low noise transistor. 7th
The figure is a sectional view of the mounting structure, and FIG.
FIG. 3 is a plan view of the mounting structure. In FIGS. 7 and 8, a high frequency low noise transistor 1 has a gate terminal 2, a drain terminal 3, and two source terminals 4, 4 which are ground terminals. This high frequency low noise transistor 1 has a ground electrode 5 on the bottom surface.
is arranged on the upper surface of the dielectric substrate 6 provided with. Further, the two source terminals 4, 4 are connected via through holes 7, 7 provided through the dielectric substrate 6 in correspondence with the two source terminals 4, 4.
and ground electrode 5 are electrically connected by soldering 8.

(Problems to be Solved by the Invention) An equivalent circuit diagram of the conventional mounting structure for the above-mentioned high-frequency, low-noise transistor is shown in FIG. As shown in FIG. 9, the gate terminal 2, drain terminal 3, and source terminal 4 of the high frequency low noise transistor 1 each have an inductance value depending on the impedance of the linear conductor of the terminal. In the conventional mounting structure of the high frequency low noise transistor described above, the two source terminals 4, 4 are connected to the ground electrode 5 in close proximity via the through holes 7, 7. The inductance value of 4,4 is extremely small. In addition, since the positions of the through holes 7, 7 to which the two source terminals 4, 4 are connected are fixed, even if the high frequency low noise transistor 1 is placed in the through holes 7, 7 with a much different position, The terminal lengths of the source terminals 4, 4 are not changed, and the inductance values of the source terminals 4, 4 cannot be changed.

By the way, in order to efficiently input the signal power from the signal source to the amplification element and amplify it with a large gain, the output inductance of the signal line and the input inductance of the amplification element must be matched, and the voltage standing wave ratio ( VSWR) must be adjusted to the minimum. Furthermore, in order to amplify the signal from the signal source with low noise, the noise figure (NF) of the amplification element must be small. Here, in order for the high frequency low noise transistor 1 to have low noise,
Gate parasitic resistance, source parasitic resistance, etc. must be small. Therefore, the high frequency low noise transistor 1 itself does not have an appropriate input impedance that minimizes the voltage standing wave ratio. For this reason, with the conventional mounting structure of high-frequency low-noise transistors, it is not possible to adjust both the voltage standing wave ratio and the noise figure to the minimum, and it is not possible to adjust both the voltage standing wave ratio and the noise figure appropriately. The current situation has no choice but to make adjustments to satisfy the situation.

Here, in the conventional mounting structure of the high frequency low noise transistor, the inductance value of the source terminals 4, 4 is small and the inductance value cannot be adjusted, so the input impedance of the high frequency low noise transistor 1 is adjusted. There was a problem that the voltage standing wave ratio could not be adjusted. Furthermore, since the inductance value of the source terminals 4, 4 is small, there is a problem in that it is not possible to apply sufficient negative feedback to the high frequency low noise transistor 1 to improve the signal-to-noise ratio.

The purpose of this invention was to solve the above-mentioned problems in the mounting structure of conventional high-frequency, low-noise transistors.One of the two ground electrodes is made into a free end shape to increase the inductance value of the ground electrode. It is an object of the present invention to provide a mounting structure for a high-frequency, low-noise transistor in which a capacitance is formed at the same time to increase the amount of negative feedback, and the amount of negative feedback and input impedance can be adjusted.

(Means for Solving the Problem) In order to achieve the above object, the high frequency low noise transistor mounting structure of the present invention has two ground terminals on the top surface of a dielectric substrate with a ground electrode provided on the bottom surface. one ground terminal of the high frequency low noise transistor is electrically connected to the ground electrode through a through hole provided in the dielectric substrate, and the other ground terminal is connected to the ground terminal in the form of a free end. A capacitance is formed between the other ground terminal and the ground electrode with the dielectric substrate interposed therebetween.

(Function) Since only one of the two ground terminals is electrically connected to the ground electrode, the inductance value of the ground terminal can be increased, and the inductance value of the ground terminal can be increased. A capacitance is formed between the ground electrode and the ground electrode. Therefore, by increasing the inductance value of the ground terminal, the amount of negative feedback can be increased and the signal-to-noise ratio can be improved. Furthermore, by adjusting the capacitance, the amount of negative feedback and input impedance can be adjusted.

(Description of Embodiments) Hereinafter, embodiments of the mounting structure for high-frequency, low-noise transistors of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a sectional view of an embodiment of the mounting structure for a high frequency low noise transistor of the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is an equivalent circuit of FIG. 1. It is. Figures 1 to 3
In the drawings, the same members and circuits as in FIGS. 7 to 9 are denoted by the same reference numerals, and redundant explanations will be omitted.

The difference between FIGS. 1 and 2 from FIGS. 7 and 8 is that a through hole 7 corresponding to one of the two source terminals 4 and 4 of the high frequency low noise transistor 1 is provided. One of the source terminals 4 is not connected to the ground electrode 5 and is disposed at a free end. Therefore, as shown in the equivalent circuit diagram of FIG. 3, a capacitor is formed between the free-end source terminal 4 and the ground electrode 5 with a dielectric substrate 6 interposed therebetween. Also, through hole 7
Since only one source terminal 4 is connected, the impedance of the source terminal 4 is doubled and the inductance value is doubled compared to the conventional mounting structure.

Therefore, by increasing the inductance value of the source terminal 4, the amount of negative feedback acting on the high frequency low noise transistor 1 increases, and the signal-to-noise ratio can be improved. In addition, the capacitance between the source terminal 4 and the ground electrode 5 can be adjusted by bending one of the free end source terminals 4 or moving the distance from the dielectric substrate 6 closer or further away. The amount of negative feedback can be adjusted appropriately through adjustment. Furthermore, since only one source terminal 4 is connected by the through hole 7, the terminal length of the source terminal 4 can be changed by shifting the position of the high frequency low noise transistor 1 with respect to the through hole 7. The inductance value can also be adjusted by Then, by adjusting the position of the high frequency low noise transistor 1 with respect to the through hole 7 and adjusting the capacitance between it and the source terminal 4, the input impedance of the high frequency low noise transistor 1 is adjusted to match the output impedance of the signal source. It is also possible to adjust the voltage standing wave ratio.

4 to 6 show other embodiments of the mounting structure for the high frequency low noise transistor of the present invention. FIG. 4 is a sectional view of another embodiment of the mounting structure for the high frequency low noise transistor of the present invention, and FIG.
6 is a plan view of FIG. 4, and FIG. 6 is an equivalent circuit of FIG. 4. In Figures 4 to 6, the first
The same members and circuits as those in the figures to FIG. 3 are given the same reference numerals, and redundant explanations will be omitted.

4 and 5, the difference from FIGS. 1 and 2 is that one source terminal 4 is not connected to the connection electrode 5 and is disposed at a free end.
An adjusting piece 9 made of copper foil or the like that can be easily plastically deformed is connected to the tip of the adjusting piece 9. Therefore, as shown in the equivalent circuit diagram in FIG. 6, a capacitor is formed between the adjustment piece 9 and the ground electrode 5 with a dielectric substrate 6 interposed, and connected in parallel to the capacitor between the source terminal 4 and the ground electrode 5. be done.

Therefore, by bending this adjustment piece 9 or adjusting the distance from the dielectric substrate 6, the combined capacitance of one of the source terminals 4 arranged in a free end shape can be greatly adjusted, and a high frequency low noise transistor can be realized. It is possible to largely adjust the amount of negative feedback to 1, and it is also possible to largely adjust the input impedance.

(Effect of the invention) As explained above, in the mounting structure of the high frequency low noise transistor according to the invention, only one of the two ground terminals is electrically connected to the ground electrode, so the inductance value of the ground terminal is In addition, a capacitance is formed between the other unconnected and free-end ground terminal and the ground electrode. Therefore, by increasing the inductance value of the ground terminal, the amount of negative feedback can be increased and the signal-to-noise ratio can be improved. Further, by adjusting the capacitance, the amount of negative feedback and the input impedance can be adjusted, which is an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the mounting structure for a high frequency low noise transistor of the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is an equivalent circuit of FIG. 1. 4 is a sectional view of another embodiment of the mounting structure for a high frequency low noise transistor of the present invention, FIG. 5 is a plan view of FIG. 4, and FIG. Fig. 4 is an equivalent circuit diagram of Fig. 4, and Fig. 7 is an equivalent circuit diagram of Fig. 4.
FIG. 8 is a cross-sectional view of an example of a conventional mounting structure for a high frequency low noise transistor, FIG. 8 is a plan view of FIG. 7, and FIG. 9 is an equivalent circuit diagram of FIG. 7. 1... High frequency low noise transistor, 4... Source terminal, 5... Ground electrode, 6... Dielectric substrate, 7
...Through hole.

Claims (1)

[Scope of utility model registration request] A high frequency low noise transistor having two ground terminals is disposed on the upper surface of a dielectric substrate having a ground electrode provided on the lower surface, and one ground terminal of the high frequency low noise transistor is provided on the dielectric substrate. The other ground terminal is electrically connected to the ground electrode through a through hole, and the other ground terminal is in a free end shape, so that a capacitance is formed between the other ground terminal and the ground electrode with the dielectric substrate interposed therebetween. A mounting structure for a high-frequency, low-noise transistor characterized by being configured as follows.