Abstract: A circuit for improving amplification and noise characteristics of a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), and a frequency mixer, an amplifier and an oscillator using the circuit are provided. A gate terminal of the MOSFET is connected to a body terminal of the MOSFET through a capacitor and the gate and body terminals of the MOSFET are connected to a current source to simultaneously provide a signal to both the gate terminal and the body terminal, in order to improve amplification and noise characteristics of the MOSFET. As a result, a higher level of amplification and a lower level of noise than the conventional art can be obtained.

Abstract: A circuit for improving amplification and noise characteristics of a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), and a frequency mixer, an amplifier and an oscillator using the circuit are provided. A gate terminal of the MOSFET is connected to a body terminal of the MOSFET through a capacitor and the gate and body terminals of the MOSFET are connected to a current source to simultaneously provide a signal to both the gate terminal and the body terminal, in order to improve amplification and noise characteristics of the MOSFET. As a result, a higher level of amplification and a lower level of noise than the conventional art can be obtained.

Abstract: A power amplifier for use in a mobile handset includes an amplifying transistor, a bias circuit including a bias transistor, the bias circuit providing a bias current to bias the amplifying transistor, and a bias current control circuit, responsive to fluctuation in a reference voltage and variation in temperature, for adjusting the bias current to control an operation current of the amplifying transistor.

Abstract: A transimpedance amplification apparatus includes a signal source for generating a current signal, a source follower stage, a common source stage and a shunt feedback resistor. The source follower stage having a source follower structure receives the current signal to reduce an impedance of the signal source. The common source stage, following the source follower stage, driven by the reduced signal source impedance, amplifies the current signal to extend a frequency bandwidth of the current signal and buffers the amplified signal with the extended frequency bandwidth thereof maintained, wherein the reduced signal source impedance serves to extend a frequency bandwidth of the common source stage. The shunt feedback resistor, which is installed between the source follower stage and the common source stage, adjusts an input DC bias of the source follower stage and increasing a transimpedance gain of the common source stage.

Abstract: In a wideband variable frequency voltage controlled oscillator, an LC resonance circuit determines an oscillation frequency based on an externally inputted voltage signal. A negative resistance generating circuit generates a signal having the oscillation frequency determined by the LC resonance circuit. A buffer circuit transfers the oscillation frequency generated by the negative resistance generating circuit to a load. A variable capacitor connecting circuit connects the negative resistance generating circuit and the buffer circuit to transfer the signal having the oscillation frequency from the negative resistance generating circuit to the buffer circuit.

Abstract: An adaptive bias circuit is provided for an amplifier module including a RF power amplifier for amplifying an input signal to generate an output signal, wherein the bias circuit receives the input signal to adjust a driving current to control a quiescent current of the RF power amplifier. The adaptive bias circuit includes means for providing the driving current to the bias circuit and means for drawing a bypass current from the providing means to reduce the driving current in response to the input signal, wherein the quiescent current is reduced when the driving current is reduced and the bypass current increases when the input signal is reduced.

Abstract: A broadband amplification apparatus for extending a bandwidth includes a first and a second amplifying unit for amplifying an input signal, a buffering unit and a first inductive buffer. The buffering unit disposed between the first and the second amplifying unit buffers an output signal of the first amplifying unit to thereby maintain a bandwidth of the output signal, increases a gain and returns back a portion of the buffered signal to the first amplifying unit. The first inductive buffer, which is connected to the buffer unit, enhances input impedance as a frequency increases within a predetermined range, thereby introducing little gain changes while serving to extend a bandwidth.

Abstract: An adaptive bias circuit is provided for an amplifier module including a RF power amplifier for amplifying an input signal to generate an output signal, wherein the bias circuit receives the input signal to adjust a driving current to control a quiescent current of the RF power amplifier. The adaptive bias circuit includes means for providing the driving current to the bias circuit and means for drawing a bypass current from the providing means to reduce the driving current in response to the input signal, wherein the quiescent current is reduced when the driving current is reduced and the bypass current increases when the input signal is reduced.

Abstract: A power amplifier for use in a mobile handset includes an amplifying transistor for generating an output of the mobile handset, a bias circuit having a bias transistor and providing a bias current to bias the amplifying transistor, and a bias current control circuit, responsive to a control signal, for adjusting the bias current to control an operation current of the amplifying transistor. The control signal is generated by the mobile handset, and the control signal is determined by a power level of the output of the mobile handset.

Abstract: A power amplifier for use in a mobile handset includes an amplifying transistor, a bias circuit including a bias transistor, the bias circuit providing a bias current to bias the amplifying transistor, and a bias current control circuit, responsive to fluctuation in a reference voltage and variation in temperature, for adjusting the bias current to control an operation current of the amplifying transistor.

Abstract: A transimpedance amplification apparatus includes a signal source for generating a current signal, a source follower stage, a common source stage and a shunt feedback resistor. The source follower stage having a source follower structure receives the current signal to reduce an impedance of the signal source. The common source stage, following the source follower stage, driven by the reduced signal source impedance, amplifies the current signal to extend a frequency bandwidth of the current signal and buffers the amplified signal with the extended frequency bandwidth thereof maintained, wherein the reduced signal source impedance serves to extend a frequency bandwidth of the common source stage. The shunt feedback resistor, which is installed between the source follower stage and the common source stage, adjusts an input DC bias of the source follower stage and increasing a transimpedance gain of the common source stage.

Abstract: A bias control circuit for a power amplifier including an RF amplifier having a transistor for power amplification, comprises two components. A first component is a bias circuit having an active bias transistor operating in an active mode and connected to a predetermined Vref pin to provide the transistor for power amplification with a base current and a second component is a bias current control circuit having another active bias transistor connected to a predetermined Vcon pin and turned on or off depending on a high or a low mode of the Vcon pin to thereby control a base current and a quiescent current of the transistor for power amplification.

Abstract: In a multilayer RF module, a plurality of vertically stacked ceramic layers include a first to a third ceramic layers. Each of the first and the third ceramic layers has a circuit component thereon and the second ceramic layer is located between the first and the third ceramic layers and is provided with at least one or more air cavities filled with air, the air cavities being vertically aligned with the circuit components of the first and the third ceramic layers.

Abstract: A broadband amplification apparatus for extending a bandwidth includes a first and a second amplifying unit for amplifying an input signal, a buffering unit and a first inductive buffer. The buffering unit disposed between the first and the second amplifying unit buffers an output signal of the first amplifying unit to thereby maintain a bandwidth of the output signal, increases a gain and returns back a portion of the buffered signal to the first amplifying unit. The first inductive buffer, which is connected to the buffer unit, enhances input impedance as a frequency increases within a predetermined range, thereby introducing little gain changes while serving to extend a bandwidth.

Abstract: A power amplifier for use in a mobile handset includes an amplifying transistor for generating an output of the mobile handset, a bias circuit having a bias transistor and providing a bias current to bias the amplifying transistor, and a bias current control circuit, responsive to a control signal, for adjusting the bias current to control an operation current of the amplifying transistor. The control signal is generated by the mobile handset, and the control signal is determined by a power level of the output of the mobile handset.

Abstract: A bias control circuit for a power amplifier including an RF amplifier having a transistor for power amplification, comprises two components. A first component is a bias circuit having an active bias transistor operating in an active mode and connected to a predetermined Vref pin to provide the transistor for power amplification with a base current and a second component is a bias current control circuit having another active bias transistor connected to a predetermined Vcon pin and turned on or off depending on a high or a low mode of the Vcon pin to thereby control a base current and a quiescent current of the transistor for power amplification.

Abstract: A 0.98 &mgr;m semiconductor laser of a ridge waveguide (RWG) structure includes: to be lengthen the durability of a semiconductor laser by increasing a catastrophic optical damage (COD) level, a ridge having a fixed width and length so that the strip may stop in the position of 30 &mgr;m on the basic of end portion of an output facet along length direction of a resonator; and a non-waveguide region in the end portion of both sides of a resonator.

Abstract: A module for mounting chips therein includes base layers for forming floors on which the chips are mounted and cavity layers having cavities through which the chips are mounted on the floors. The floors has a top surface provided with contact regions for electrical connection with the chips and the cavity layers has a top surface provided with bonding pads for electrical connection with a printed circuit board. The cavity layers are disposed on the top surface of the base layers to expose the contact regions through the cavities.

Abstract: A 0.98 &mgr;m semiconductor laser of a ridge waveguide (RWG) structure includes: to be lengthen the durability of a semiconductor laser by increasing a catastrophic optical damage (COD) level, a ridge having a fixed width and length so that the strip may stop in the position of 30 &mgr;m on the basic of end portion of an output facet along length direction of a resonator; and a non-waveguide region in the end portion of both sides of a resonator.

Abstract: A 0.98 &mgr;m semiconductor laser of a ridge waveguide (RWG) structure includes: to be lengthen the durability of a semiconductor laser by increasing a catastrophic optical damage (COD) level, a ridge having a fixed width and length so that the strip may stop in the position of 30 &mgr;m on the basic of end portion of an output facet along length direction of a resonator; and a non-waveguide region in the end portion of both sides of a resonator.