Power amplifier operating at a fixed frequency or a narrow bandwidth and based upon a non-linear gain element. The power amplifier includes a resonant circuit operably connected to the non-linear gain element, the circuit being resonant at a harmonic of substantially the band center frequency of the non-linear gain element and being arranged to dissipate energy resulting from harmonic generation by the non-linear gain element during signal amplification. In a particular aspect of the power amplifier, resonant circuits comprising inductor-capacitor harmonic trap circuits tuned to different harmonics are placed at both the input and the output of a gallium arsenide heterojunction bipolar transistor HBT providing the non-linear gain element.

Power amplifier with harmonically trapped heterojunction bipolar transistor

A bypass device in a low noise amplifier unit for amplifying communication signals in the microwave frequency range. The device includes a printed circuit board with transmission lines (1, 2), an amplifier (A), a transmission line bypass segment (3) extending in parallel to the amplifier, and switching means for activating said bypass segment in case the amplifier becomes inoperable. The amplifier is connected between two transmission line stub segments (4, 5). The switching means include solid state components (Z1, Z2, Z3, Z4) having a controllable impedance, either very low or very high, these components being connected to ground at selected points (3a, 3b, 4a, 4b) in the bypass segment (3) and in the stub segments (4, 5) so as to activate the bypass segment when all of said solid state component are in a state of very high impedance and to effectively cut off the bypass segment when all of said solid state components are controlled to a state of very low impedance, in which case the communication signals pass through the amplifier.

Bypass device in an amplifier unit

PURPOSE:To provide a highly efficient amplifier circuit capable of short- circuiting the 2nd higher harmonic and opening the 3rd higher harmonic without reducing the impedance of a reference wave on the output terminal of a high output transistor(TR). CONSTITUTION:In a highly efficient impedance matching circuit for the impedance ZTr of a high output TR element to be used for a transmission line with characteristic impendance Zo, a transmission line 2 with characteristic impedance ZTo (ZTrZo) 1/4 wavelength is connected between a TR terminal 6 and a higher harmonic processing circuit consisting of two parallel stubs 3, 4 having respectively optional characteristic impedance values and 1/8 wavelength and 1/12 wavelength and opened at their tips on a connecting position between the two transmission lines.

Highly efficient amplifier circuit

PURPOSE:To easily correct impedance dispersion in a high frequency transistor(TR) by connecting a wire in parallel with a MOS capacitor being a component of an impedance conversion circuit so as to form a parallel resonance circuit. CONSTITUTION:A wire 17 is provided in parallel with a MOB capacitor 8 being a component of an input side impedance conversion circuit. A change in a susceptance DELTAB by a capacitor 8 and a wire 17 is expressed in DELTAB=omegaC-1/omegaL, where C is the capacitance of the capacitor 8, L is an inductance of the wire 17 and omega is an angular frequency of an input signal. Thus, a change due to the impedance dispersion or the like in a TR chip 1 is absorbed by changing the number of wires 17 and the length or the like so as to adjust the inductance L. For example, when the actually measured impedance of the chip 1 is larger than a specified value, the number of the wires 17 and the length are increased to increase the admittance thereby reducing the impedance.

High frequency transistor circuit

PURPOSE:To grasp the stocks of consumption goods and to prevent shortage of them by installing a computer control circuit for the stocks of the consumption goods to be used for a copying machine and a display device, etc., for warning of shortage of the stocks and indicating the remaining amts. of them. CONSTITUTION:The detector 2 of kinds of papers detects them, a consumption detector 3 detects it, and a set value input device 4 receives the stocks of the consumption goods and provides the input signals to a copy controller 1. When it is judged by a judging device 5 from the remaining amts. of the stocks that the time to replenish them comes now, it is indicated on the display device 6. The set values of stocks of the consumption goods and the remaining amt. to be warned of are stored in a nonvolatile memory 7 to control the stocks, thus permitting the stocks of the consumption goods, such as papers, a toner, and a fixing oil, to be controlled, and hence, suspension of the copying operation due to shortage of the stocks to be prevented.

Copy control system

PURPOSE:To eliminate a higher harmonic sufficiently by providing an end opening transmission line filter, which is short-circuited for the higher harmonic, in the output side. CONSTITUTION:In case the length l of end opening stub 26 provided on the transmission line is l<1/4 wave length, the stub is capasitive; and in case of l=1/8 wave length, the susceptance of stub 26 is equal to the characteristic admittance of the transmission line which stub 26 has. Then, matching in the output side can be taken by changing the characteristic admittance by changing the line width of stub 26. Meanwhile, the 1/8 wave length line for the fundamental wave becomes 1/4 wave length for the second higher harmonic, and the susceptance which stub 26 has is infinite. Consequently, stub 26 operates as a removal filter for the second higher harmonic. A 1/12 wave length stub is used for the third higher harmonic. Further, this unit is made into a MIC, and plural stubs are provided, so that it becomes small-size and can be operated efficiently.

Unarin Masataka

Papers

Highhfrequency transistor power amplifier