JPS62292006A - Amplifier - Google Patents

Abstract

PURPOSE:To obtain an amplifier which can decide a frequency range by a simplified constitution, by cascade-connecting an emitter-earthed circuit to a base-earthed circuit, and earthing the emitter of the amplifier having inductance load, through a resitor and a capacitor. CONSTITUTION:An emitter-earthed transistor TrQ1 and a base-earthed TrQ2, are cascade-connected, and inductance load L1 is connected to the collector of the TrQ2. By earthing the emitter of the TrQ1 through a current series feedback resistor R1, and a capacitor C1, and connecting the base of the TrQ1 to the collector of the TrQ2 through a capacitor C2, and a loop feedback resistor R2, a voltage parallel feedback circuit is formed. Impedance is increased at a low frequency area by the capacitor C1, and a series feedback quantity is increased, and a low-pass side receives the limitation of a gain. Therefore, it is possible to constitute a device in the simplified constitution at low cost, to reduce the gain at the low-pass area, eliminating the need to use an HPF.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Industrial application field] The present invention relates to amplifiers, and particularly to high frequency amplifiers.

[Conventional technology]

Conventionally, this type of amplifier, especially a high-frequency loop feedback type amplifier, has an emitter-grounded circuit at the first stage and a base-grounded circuit at the final stage connected in cascade, and an electronic circuit with an inductance component such as a transformer as a load. there were.

[Problem that the invention seeks to solve]

In the conventional amplifier described above, in order to reduce the low-frequency gain and determine the frequency band of the electronic circuit, a high-pass filter must be inserted before or after the electronic circuit, making the circuit configuration complicated. There is a problem that it becomes expensive.

An object of the present invention is to provide an amplifier that can determine the frequency band of an electronic circuit with a simple circuit configuration.

[Means for solving problems]

The amplifier of the present invention is an electronic circuit in which a common emitter circuit and a common base circuit are connected in series and has an inductance component as a load. Configured to connect to a ground terminal.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention.

As shown in FIG. 1, in this embodiment, the emitter is connected to the ground terminal via the series-connected current series feedback resistor R1 and the capacitor C1, and the pace is connected to one electrode of the capacitor C2. A transistor Q1 has an emitter connected to the collector of a transistor Qh, a base connected to a ground terminal, and a collector connected to the other ! of a capacitor C2 through a loop feedback resistor R2. It is configured to include a second transistor Q2 connected to the pole, and an inductance L1 having one terminal connected to the collector of the transistor (h) and the other terminal connected to the ground terminal.

A voltage parallel feedback resistor 1 and a capacitor C1 connected to the emitter of the transistor Ql form a 1-current series feedback circuit, and a loop feedback resistor R2 inserted in series between the collector of the transistor Q2 and the base of the transistor Q1 is connected to the emitter of the transistor Q1. Forms a voltage parallel feedback circuit.

FIG. 2 is a gain versus frequency characteristic diagram of the embodiment shown in FIG. 1.

The reason why the gain of the electronic circuit can be reduced in the low range by inserting the capacitor C1 in series with the current series feedback resistor R1 in the emitter of the transistor Ql in FIG. 1 will be explained with reference to FIG. 2.

In Figure 2, when current series feedback and voltage parallel feedback without capacitor C1 are applied to an amplifier that has the gain vs. frequency characteristic without feedback shown by the dashed line, a wide band extending to the low range as shown by the broken line is generated. Shows gain versus frequency characteristics.

Here, if you want to reduce the gain on the low frequency side, insert a capacitor C1 in series with the lightning series feedback resistor R1.
In the low frequency range, the capacitor's impedance is high, so the amount of series feedback increases, and the low frequency side is subject to gain limitations. On the other hand, in the high range, the impedance of the capacitor C1 decreases, and only the action of the current series feedback resistor R1 acts, resulting in the gain versus frequency characteristic shown by the solid line in FIG. Note that the bias circuit is not shown in FIG. 1.

〔Effect of the invention〕

As explained above, the amplifier of the present invention uses a high-pass filter to reduce the low-frequency gain by connecting the emitter of a common-emitter transistor to the ground terminal via a resistor and a capacitor connected in series. This method has the advantage of being simple and inexpensive since it does not require the use of .

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a gain versus frequency characteristic diagram of the embodiment shown in FIG. C1, C2... Capacitor b"1...
Inductance % Q1+Q2...Transistor, R1...Current series feedback resistor, R2...
...Loop feedback resistance. Agent Patent Attorney Susumu Uchihara PaCt, Cz
: Ko〉Ding゛Saw Lt: By inductance Z

Claims (1)

[Claims] In an amplifier which is an electronic circuit in which a common emitter circuit and a common base circuit are connected in cascade and has an inductance component as a load, the emitter of the common emitter circuit is connected to a ground terminal via a resistor and a capacitor connected in series. An amplifier featuring: