Abstract: There is provided a quadrature modulation transmitter which is capable of solving several problems of the conventional transmitter while performing the same function as the heterodyne transmitter or the digital IF transmitter, in which a circuit structure is simplified and a power consumption is reduced compared with the conventional transmitter.

Abstract: A variable gain amplifier (VGA) circuitry for implementing gain as a pseudo exponential function by using the linear area of metal oxide semiconductor field effect transistors (MOSFETs) is provided. The VGA circuitry includes a fixed resistor and a variable resistor, which is connected in serial to the fixed resistor and implemented by combining one or more MOSFETs operating in a linear area with different control voltages to each MOSFET. Although the MOSFET has no exponential characteristics, the VGA circuitry can easily implement a pseudo exponential function with a simple structure. Further, since a complex circuit for generating an exponential function is not necessary, power consumption thereof can be eliminated.

Abstract: Disclosed are flat/vertical type vacuum field transistor (VFT) structures, which adopt a MOSFET-like flat or vertical structure so as to increase the degree of integration and can be operated at low operation voltages at high speeds. The flat type comprises a source and a drain, made of conductors, which stand at a predetermined distance apart on a thin channel insulator with a vacuum channel therebetween; a gate, made of a conductor, which is formed with a width below the source and the drain, the channel insulator functioning to insulate the gate from the source and the drain; and an insulating body, which serves as a base for propping up the channel insulator and the gate.