Amplifiers – With semiconductor amplifying device – Including signal feedback means
Patent
1986-05-23
1988-08-16
Mullins, James B.
Amplifiers
With semiconductor amplifying device
Including signal feedback means
330297, 330306, 330311, H03F 134
Patent
active
047647361
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an amplifier for a high frequency signal used to amplify a high frequency signal in a television tuner, a receiver for satellite broadcasing, or the like.
BACKGROUND ART
In the prior art, in order to obtain a high gain in an amplifier circuit for a high frequency signal for processing a high frequency signal of which the frequency is at least in the 100 MHz band, a multistage cascade circuit of the grounded-emitter type amplifier as shown in FIG. 1A has been commonly used. In FIG. 1A, a high frequency signal is supplied from an input terminal IN and is amplified by two stages of transistors Q.sub.1 and Q.sub.2, and then is delivered from an output terminal OUT. To integrate the circuit of FIG. 1A, the configuration must be sealed in an IC package 1 as shown in FIG. 1B. Since the pins 1a, 1b, 1c, and 1d of the IC package 1 are connected to the IC chip by use of bonding wires, the circuit include wire inductances such as L.sub.in, L.sub.G, L.sub.out, and L.sub.B shown in FIG. 1B. These wire inductances are ordinarily of a value from 2.5 nH to 5 nH, which is ignorable for a lower frequency. For a high frequency signal of which the frequency is at least 800 MHz, the wire inductance cannot be ignored. In the circuit of FIG. 1, the influence of the wire inductances L.sub.IN, L.sub.B, and L.sub.out can be removed by use of an external circuit or resistors R.sub.1, R.sub.3, and R.sub.4 in the IC; however, the influence of the inductance L.sub.G inserted between the circuit and a grounding (GND) cannot be eliminated. In the example of this figure, it particularly causes a problem that the common inductance component is inserted for the emitters of the transistors Q.sub.1 and Q.sub.2, which configures a feedback loop and therefore leads to a serious drawback that the circuit starts oscillation. In FIG. 1C, a resistor R.sub.5 is inserted into the emitter of the transistor Q.sub.2 of FIG. 1B and the bonding wire inductance L.sub.G2 is grounded through a bypass capacitor C connected externally with respect to the IC, thereby attempting to improve the oscillation described above. Although any problem may not arise in the case with only the transistor Q.sub.1, if the transistors Q.sub.1 and Q.sub.2 are connected, the emitter of the transistor Q.sub.1 is connected to the grounding in the IC, that is, there exists the wire inductance L.sub.G1 in addition to the wire inductance L.sub.G2, which makes the grounding potential of the circuit unstable; consequently, even if no problem is caused in the case including only the wire inductance L.sub.G1, the circuit has a drawback that the oscillation state cannot be prevented in the multistage casecade connection.
DISCLOSURE OF INVENTION
An object of the present invention is to provide in such a multistage cascade integrated circuit system for a high frequency signal an amplifier for a high frequency which is capable of obtaining a stable operation without causing the oscillation phenomenon.
Another object of the present invention is to provide an amplifier for a high frequency signal which can easily achieve an operation to attain a sharp frequency characteristic and a phase shift operation.
Still another object of the present invention is to provide an amplifier for a high frequency signal which is capable of improving the gain without increasing the number of elements and the current consumption.
Another object of the present invention is to provide an amplifier for a high frequency signal which can remove the image disturbance by use of a simple configuration.
The amplifier for a high frequency signal according to the present invention includes an integrated circuit configured by a circuit in which at least two stages of grounded-emitter type amplifiers are connected by use of a direct current coupling, furthermore an emitter resistor is connected between an emitter of the second-stage amplifier and the grounding, at least a terminal of said second-stage amplifier is connected via a bonding wire of the integrated circuit t
REFERENCES:
patent: 3441865 (1969-04-01), Siwko
patent: 4507620 (1985-03-01), Buisson et al.
Kubo Kazuhiko
Nagai Hiroyuki
Usui Akira
Yamada Tadashi
Matsushita Electric - Industrial Co., Ltd.
Mullins James B.
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