JPH04154310A - Transistor amplifier - Google Patents

Abstract

PURPOSE:To divide and set the frequency band into two by connecting a series resonance circuit containing a capacitor and an inductance connected in series to each other in parallel to a voltage parallel feedback circuit. CONSTITUTION:A resistance R1 for voltage parallel feedback connected between a base of a transistor Q1 and a collector of a transistor Q2, and a series resonance circuit constituted of an inductance L1 and a capacitor C1 connected in series to each other form a voltage parallel feedback circuit. When a voltage parallel feedback and a current series feedback having no resonance circuit of the inductance L1 and the capacitor C1 connected in series to each other are performed to an amplifier having a gain frequency characteristic curve at the time of no-feedback, a gain frequency characteristic of a wide band extending from a low frequency to a high frequency is obtained. In such a way, the band can be divided into two.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to transistor amplifiers, and more particularly to high frequency broadband transistor amplifiers.

[Conventional technology]

For example, conventionally, in bipolar transistor amplifiers,
In particular, high-frequency loop feedback broadband amplifiers have a first stage common emitter circuit and a final stage common base circuit connected in cascade, and the input of the first stage common emitter circuit is connected to the pole and the output electrode of the final stage common base circuit is connected in cascade. There was a circuit with a voltage parallel feedback resistor connected between them.

When using this transistor amplifier divided into two frequency bands, a bandpass filter or notch filter is inserted before or after the electronic circuit.

[Problem to be solved by the invention]

In the conventional transistor amplifier mentioned above, in order to divide the amplifier into two frequency bands, a bandpass filter or notch filter is inserted before or after the electronic circuit, making the circuit configuration complicated and expensive. There was a problem.

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

[Means to solve the problem]

The transistor amplifier of the present invention includes a cascade-connected emitter (source) grounded circuit and a base (gate) grounded circuit, and an input electrode of the emitter (source) grounded circuit and an output electrode of the base (gate) grounded circuit. A transistor amplifier comprising a voltage parallel feedback circuit including a feedback resistor connected in parallel between the voltage parallel feedback circuit and the voltage parallel feedback circuit configured by connecting a series resonant circuit including a capacitor and an inductance connected in series to the voltage parallel feedback circuit. ing.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing the main parts of the first embodiment of the present invention.
A case is shown in which an NPN type bipolar transistor is used as the transistor. Note that the bias circuit is omitted.

This embodiment includes a current series feedback circuit consisting of a transistor Q1, an emitter resistor R2 whose one end is connected to the emitter as an input electrode of the transistor Q1, and whose other end is grounded, and a current series feedback circuit cascade-connected with this circuit. The transistors are connected in series to a transistor amplifier having a voltage parallel feedback circuit consisting of a feedback resistor R1 connected between the collector, which is the output electrode of the common base circuit of the transistor Q2, and the base, which is the control electrode of the transistor Q1. A series resonant circuit consisting of an inductance L1 and a capacitor C1 is connected in parallel to a resistor R1.

Next, the operation of this embodiment will be explained with reference to the gain frequency characteristic diagram shown in FIG.

A voltage parallel feedback resistor R1 connected between the base of the transistor Q1 and the collector of the transistor Q2, and a series resonant circuit composed of an inductance L1 and a capacitor C1 connected in series form a voltage parallel feedback circuit. are doing.

In FIG. 2, voltage parallel feedback and current series feedback without a resonant circuit of an inductance L1 and a capacitor C1 connected in series are applied to an amplifier having a gain frequency characteristic curve 10 without feedback shown by the - point ta line. As shown by the broken line 11 and solid lines 12 and 13, a wide band gain frequency characteristic curve extending from the low range to the high range is shown.

Here, the gain frequency band is set to, for example, the VHF band (30M
Hz ~ 300 MHz) and UHF band (470 MHz)
MHz to 900 MHz), insert a series resonant circuit of inductance L1 and capacitor C1 in parallel to resistor R1 for voltage parallel feedback, and the resonance frequency of inductance Ll and capacitor C1 ( (approximately 380 MHz), the parallel feedback increases due to the low impedance, limiting the gain in the middle of the band.

On the other hand, in the low and wide ranges, the impedance of the series resonant circuit of inductance L1 and capacitor C1 increases, and the effect of resistor R1 for voltage parallel feedback comes into play. Gain frequency characteristic curves 12 and 13 can be obtained.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention. In this embodiment, in the circuit of FIG. 1, an inductance L2 is inserted to apply peaking to the voltage parallel feedback circuit including the feedback resistor R1. and capacitor C to apply emitter peaking to the current series feedback circuit of resistor R2.
2 was inserted.

Thereby, the band of the gain versus frequency characteristic on the high frequency side can be extended.

In the above first and second embodiments, a bipolar transistor was used as the transistor, but a field effect transistor was used by setting the input electrode as the source electrode, the output electrode as the drain electrode, and the control electrode as the gate electrode. It also applies in cases.

[Effects of the Invention] As explained above, the present invention provides a cascade connection between the base (gate) of the first stage common emitter (source) circuit and the collector (drain) of the final stage common base (gate) circuit. By connecting a resistor in parallel with a series resonant circuit including an inductance and a capacitor connected in series, it is possible to divide the band into two without using a bandpass filter or notch filter. This configuration has the effect of being inexpensive.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a gain frequency characteristic diagram for explaining the operation of the circuit in FIG. 1, and FIG. 3 is a circuit diagram showing a second embodiment of the present invention. FIG. 10-13...Gain frequency characteristic curve, C1, C2...
・Capacitor, Ll, L2...Inductance, Ql
, Q2...Transistor, R1, R2...Resistor.

Claims (1)

[Claims] comprising a cascade-connected emitter (source) grounded circuit and a base (gate) grounded circuit, and the emitter (
In a transistor amplifier comprising a voltage parallel feedback circuit including a feedback resistor connected in parallel between an input electrode of a source (source) grounded circuit and an output electrode of the base (gate) grounded circuit, a capacitor and an inductance connected in series with each other are used. A transistor amplifier comprising a series resonant circuit connected in parallel to the voltage parallel feedback circuit.