摘要:
A high-frequency amplifier module includes a driver-stage amplifier 3 that amplifies an RF signal input thereto from an RF input terminal 1, and a final-stage amplifier 5 that amplifies the signal amplified by the driver-stage amplifier 3 and outputs the signal after the amplification to an RF output terminal 7. The driver-stage amplifier 3 is fabricated on a silicon substrate 11, while the final-stage amplifier 5 is fabricated on a gallium arsenide substrate. This configuration downsizes the cost while maintaining a high-frequency characteristic comparable to that in the case where all components of an entire module are fabricated on a gallium arsenide substrate 71.
摘要:
Disclosed is an output overvoltage protection circuit for a power amplifier having a plurality of stages, which comprises a monitor circuit for monitoring an output overvoltage of an output transistor in the final stage of the power amplifier and allowing a current to flow therethrough in response to the monitored output overvoltage, and a current mirror circuit for supplying a current proportional to the current from the monitor circuit in such a manner that the base bias of the first-stage transistor of the power amplifier is reduced in response to the current supplied from the current mirror circuit, to reduce the output of the final-stage output transistor.
摘要:
A power amplifier according to the present invention is operated by switching a main power amplifier and a subsidiary power amplifier. The idle current of the subsidiary power amplifier is smaller than the idle current of the main power amplifier. Each of the main power amplifier and the subsidiary power amplifier has a former amplification element for amplifying RF signals, a latter amplification element for amplifying output signals from the former amplification element, a former bias circuit for driving the former amplification elements, and a latter bias circuit for driving the latter amplification elements, respectively. The interval between the latter amplification element of the main power amplifier and the latter amplification element of the subsidiary power amplifier is not more than 100 μm. The interval between the latter amplification element of the main power amplifier and the latter bias circuit of the subsidiary power amplifier is not less than 200 μm.
摘要:
A power amplifier according to the present invention is operated by switching a main power amplifier and a subsidiary power amplifier. The idle current of the subsidiary power amplifier is smaller than the idle current of the main power amplifier. Each of the main power amplifier and the subsidiary power amplifier has a former amplification element for amplifying RF signals, a latter amplification element for amplifying output signals from the former amplification element, a former bias circuit for driving the former amplification elements, and a latter bias circuit for driving the latter amplification elements, respectively. The interval between the latter amplification element of the main power amplifier and the latter amplification element of the subsidiary power amplifier is not more than 100 μm. The interval between the latter amplification element of the main power amplifier and the latter bias circuit of the subsidiary power amplifier is not less than 200 μm.
摘要:
Disclosed is an output overvoltage protection circuit for a power amplifier having a plurality of stages, which comprises a monitor circuit for monitoring an output overvoltage of an output transistor in the final stage of the power amplifier and allowing a current to flow therethrough in response to the monitored output overvoltage, and a current mirror circuit for supplying a current proportional to the current from the monitor circuit in such a manner that the base bias of the first-stage transistor of the power amplifier is reduced in response to the current supplied from the current mirror circuit, to reduce the output of the final-stage output transistor.
摘要:
A high-frequency semiconductor device according to the present invention achieves improvements in degradation of noise characteristics and a reduction in gain, and an improvement in reduction in power efficiency while suppressing a concentration of a current to multifinger HBTs. In the multifinger HBTs constituting a first stage and an output stage of an amplifier 10, basic HBTs 14 that constitute the multifinger HBT 12 corresponding to the first stage, are each made up of an HBT 14a and an emitter resistor 14b connected to the corresponding emitter of the HBT 14a, whereas basic HBTs 18 that constitute the multifinger HBT 16 corresponding to the output stage, are each comprised of an HBT 18a and a base resistor 18c connected to the corresponding base of the HBT 18a. The high-frequency semiconductor device according to the present invention is useful as a high output power amplifier used in satellite communications, ground microwave communications, mobile communications, etc.
摘要:
A bias circuit for a bipolar transistor includes a constant voltage source connected to a base electrode of the bipolar transistor; and a resistor connected in series between the constant voltage source and the base electrode of the bipolar transistor. By selecting an appropriate resistance for this resistor, the bias point moves due to a change in the voltage drop across the resistor. The change occurs because the base current flowing through the resistor changes, whereby the operating class of the transistor changes, resulting in a high efficiency at a desired output power.
摘要:
A method of producing a MESFET which includes forming a refractory metal gate structure on an active layer formed in or on a semiconductor substrate. Source and drain regions optionally with extensions, are formed adjacent the gate structure. An insulating film is deposited over the partly formed structure to form a film portion on the semiconductor substrate which is separated from further film portions formed over the source and drain regions. A flattening resist is deposited over the insulating film and etched to expose only the film portion on the gate structure, while the gate structure itself and the resist protects the film portions on the source and drain regions. The film portion over the gate structure can thus be removed without damage to the gate structure or the remainder of the insulating film. The process produces with increased yield and more consistent properties in that the danger of attacking the refractory metal gate structure during operations succeeding its formation is significantly reduced.
摘要:
A heterojunction bipolar transistor is provided with a ballast resistor layer in an emitter layer which prevents the current amplification factor .beta. from decreasing. The n-GaAs carrier supply layer having a specified carrier concentration is formed between the ballast resistor layer and the n-AlGaAs layer.
摘要:
A field effect transistor including a semi-insulating semiconductor substrate, a first conductivity type semiconductor layer disposed on the substrate and forming a heterojunction with the substrate, second conductivity type spaced apart source and drain regions extending through the layer into the substrate, a metallic gate disposed on the layer between the source and drain regions, and a second conductivity type channel disposed in the substrate extending between the source and drain regions and forming a pn heterojunction with the layer for reducing leakage current from the channel to the gate. The second conductivity type channel is produced by ion implantation, and the implantation conditions are controlled as a mechanism for controllably establishing a threshold voltage for the field effect transistor.