JPS60236508A - Wide band amplifier - Google Patents

Abstract

PURPOSE:To increase easily the impedance at the input side by using a high frequency transistor having a discoid shell and two long emitter leads, a base lead and a collector lead extended in four directions from said shell as an active element of an emitter-earthed amplifier circuit. CONSTITUTION:A high frequency transistor 26 uses a micro-X type or a disk mold type containing two long emitter leads 42, a long base lead and a collector lead extended in four directions from a discoid shell 40. The both sides of copper foils 52 and 52 of reference potential point are cut in triangular shapes at the areas having contacts with emitter leads 42 respectively. Thus the inductance component is produced in a frequency area of a wide-band signal supplied to an input contact plug 20 and between both foils 52 and a contact copper foil part 54. This is equivalent to a case where an inductance 56 is put between both leads 42 and a reference potential point. Therefore the input impedance of an emitter-earthed amplifier circuit 24 is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a wideband amplifier that amplifies a wideband signal such as a VHF band or a UHF band.

<Prior art> Conventionally, in a wideband amplifier, as shown in FIG.
There are those that amplify the signal and output it from the output plug 3, and those that have a multistage type in which two or more stages of such common emitter type amplifier circuits 2 are connected in series.

This emitter grounded amplifier circuit 2 has two emitter leads 12, one collector lead 13,
Using a disk mold type or Micro
Furthermore, to prevent parasitic oscillation from occurring due to the parasitic impedance of each lead of the high frequency transistor 4,
Furthermore, in order to prevent the gain from decreasing as the frequency increases, the high frequency transistor 4 is mounted directly on the printed circuit board 15, and the emitter leads 12, 12 are connected to the reference potential point pattern 16 at the shortest distance. There is.

Although not shown in Figure 10, the collector lead 1
3. The base lead 14 is connected to the capacitor 7.8 via the land formed on the printed circuit board 15 as shown in FIG.
Connected to resistor 9.10.

<Problems to be Solved by the Invention> However, the input impedance of the common emitter amplifier circuit 2 is often lower than the impedance of a line such as a coaxial cable connected to the manual plug 1;
If the line is directly connected to the common emitter amplifier circuit 2, the line and the common emitter amplifier circuit 2 will not match, and the VS
When the WR (voltage standing wave ratio) becomes large and a difference in gain occurs depending on the frequency within the band, the high frequency transistor 4 may cause oscillation.

Therefore, a feedback circuit is provided in the emitter-grounded amplifier circuit 2 to increase the input impedance and match with the line, and a matching transformer is installed between the input plug 1 and the input side of the emitter-grounded amplifier circuit 20. However, all of them had problems such as reduced gain, worsened noise characteristics, and increased cost.

<Means for solving the problem> The solution to the above problem is to use a wideband amplifier that is configured on a printed circuit board and has a common emitter type amplifier circuit that amplifies the wideband signal input from the input connector. In the above, as an active element of the common emitter type amplifier circuit, ′
A high-frequency transistor having a disk-shaped outer shell □ and two long emitter leads, one base lead, and one collector lead extending in all directions from the outer shell is used,
'A metal pattern having an inductance component in the broadband signal frequency band is formed in line with the metal pattern at the reference potential point near the two emitter leads on the printed circuit board, and the emitter lead is connected to this metal pattern. It is.

<Function> According to this means, the emitter lead of the high frequency transistor is connected to the reference potential point via the inductance, and the input impedance of the common emitter amplifier circuit increases, and the emitter lead of the high frequency transistor is directly connected to the common emitter amplifier circuit. Even if the input connector is connected to the circuit, it can be matched with a line such as a coaxial cable connected to the input connector.

<Embodiment> The present invention includes a common emitter type amplifier circuit 24 that amplifies a region input signal and outputs it to the output plug 22. This emitter-grounded amplifier circuit 24 includes a high-frequency transistor 26, two long emitter leads 42, 42, and one long base lead 4.
A disk mold type or My Flora type with four and one collector leads 46 extending in all directions is used. As shown in FIG. 2, the high frequency transistor 26 is arranged such that the outer shell 40 is located within an opening 50 formed vertically through the printed circuit board 48.

Although not shown in FIG. 1, the base lead 44 is connected to the capacitor 32 and the resistor 36 via lands formed on the printed circuit board 48, and is similarly connected to the collector lead 44.
6 is connected to a capacitor 34 and a resistor 38.

A reference potential point copper foil 52.52 is formed near the tip of the emitter lead 42.42 so as to be in contact with the tip, and the tip is connected to the contact position. The copper foils on both sides of the portion where the reference potential point copper foil 52.52 and the emitter lead 42.42 are in contact are each triangularly cut out, and the contacting copper foil portion 54 and the other reference potential point copper foils are cut out. 52.52, an inductance component occurs in the frequency band of the broadband signal input to the input connector 20.

With this configuration, as shown in FIG. 3, it is equivalent to having an inductance 56 interposed between the emitter leads 42, 42 and the reference potential point. Therefore, the input impedance of the common emitter amplifier circuit 24 increases.

Therefore, when comparing a conventional wideband amplifier and this wideband amplifier, as shown in FIG. 4, the SWR of this wideband amplifier is smaller than that of the conventional wideband amplifier at any frequency within the band. A second embodiment is shown in FIG. In this embodiment, a copper foil portion 5 having an inductance component is used.
The structure is similar to that of the first embodiment except that 4a has a crank-like elongated shape that protrudes from the edge of the reference potential point copper foil 52 toward the high-frequency transistor 26 side.

FIG. 8 shows a third embodiment. In this embodiment, the copper foil portion 541) having an inductance component is formed by cutting out a rectangular shape on both sides of the reference potential point copper foil portion in contact with the emitter and the lead 42.42. It is configured similarly to the example.

In the above embodiment, only one stage of the common emitter type amplifier circuit 24 is provided, but multiple stages may be connected in series.

<Effects of the Invention> As explained above, according to the present invention, the impedance on the input side can be increased without using a feedback circuit or a matching transformer, and a wideband amplifier with good characteristics can be achieved at low cost. can be realized.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the mounting state of the high-frequency transistor of the first embodiment of the broadband amplifier according to the present invention, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. The circuit diagram, FIG. 4, shows the VS of the first embodiment and the conventional wideband amplifier.
WR vs. frequency characteristic diagram, Figure 5 is the same gain vs. frequency characteristic diagram,
Fig. 6 is a noise characteristic diagram of the same, Fig. 7 is a plan view showing the mounting state of the high frequency transistor of the second embodiment, and Fig. 8 is a plan view showing the mounting state of the high frequency transistor on the downstream side of the third embodiment. , FIG. 9 is a circuit diagram of a conventional wideband amplifier, and FIG. 1O is a plan view showing how the high frequency transistor of the conventional wideband amplifier is mounted. 24... Emitter grounded amplifier circuit, 26... High frequency transistor, 42... Emitter lead, 44...
Base lead, 46...Collector lead, 48...
Print base 4L52...Reference potential point metal pattern, 5
4, 54a, 541)...Metal pattern having an inductance component. Patent Applicant Diex Antenna Co., Ltd. Agent Tetsu Shimizu and 2 others No. 10, 3rd, 4th, 6th, 7th, 8th ') 41), 9th

Claims (1)

[Claims] (1) In a wideband amplifier having a common emitter type amplifier circuit configured on a printed circuit board and amplifying a wideband signal input from an input connector, a disc-shaped outer shell is used as an active element of the common emitter type amplifier circuit. A high-frequency transistor is used in which two long emitter leads, one bene lead, and one collector lead extend in all directions from the outer shell, and a reference potential point near both emitter leads on the printed circuit board is used. A wideband amplifier characterized in that a metal pattern having an inductance component in the broadband signal frequency band is formed in parallel with the metal pattern, and the emitter lead is connected to the metal pattern.