A relatively high power active gain device, such as MESFET or similar transistor, has distributed impedance characteristics at relatively high RF (microwave) frequencies of operation due to physical device size limitations. A transmission line segment (104) is placed in relatively close spacial relationship and is coupled in parallel electrical relationship with the input port (162) of the high power active device. This provides for highly simplified design of an impedance prematched amplifier (100) over a relatively broad range of predetermined input signal center frequencies. An active device (102) is provided based on power requirements and is characterized over a range of center frequencies and device sizes independently from the characterization of the transmission line segment (104) over a range of center frequencies and segment lengths, since the impedance characteristics of the active device (102) and the transmission line (104) are not dependent upon each other. Based on a predetermined operating center frequency and on the input source impedance characteristics, an appropriate pre-characterized transmission line segment (104) is paired with an appropriate pre-characterized active device (102) based on a simplified model for the prematched amplifier (100). Characterization procedures are therefore simplified and relatively inexpensive. The design cycle for a prematched amplifier is considerably simplified, shortened, and reduced in cost.
The present invention is directed to improve high frequency characteristics by reducing inductance of a source. In an HEMT assembled in a power amplifier device, each of a drain electrode, a source electrode, and a gate electrode is constructed by a base portion and a plurality of fingers projected in a comb-teeth shape from the base portion, and the fingers of the electrodes mesh with each other. In the source electrode, a width of the fingers positioned at both ends of the plurality of fingers is wider than a width of each of the fingers positioned between both ends. The width of each of the fingers positioned at both ends is a width equal to or larger than a sum of the widths of the plurality of fingers positioned between both ends, and the width of the base portion is wider than that of each of the fingers positioned at both ends. An electrode pad provided for the source base portion and an external electrode terminal are connected to each other via a conductive wire.
A built-in-self test (BIST) scheme for analog circuitry functionality tests such as frequency response, gain, cut-off frequency, signal-to-noise ratio, and linearity measurement. The BIST scheme utilizes a built-in direct digital synthesizer (DDS) as the test pattern generator that can generate various test waveforms such as chirp, ramp, step frequency, two-tone frequencies, sweep frequencies, MSK, phase modulation, amplitude modulation, QAM and other hybrid modulations. The BIST scheme utilizes a multiplier followed by an accumulator as the output response analyzer (ORA). The multiplier extracts the spectrum information at the desired frequency without using Fast Fourier Transform (FFT) and the accumulator picks up the DC component by averaging the multiplier output.
A multicell transistor for use in a circuit has an input ground plane for an input waveguide and an output ground plane for an output waveguide. The multicell transistor includes a gate electrode coupled to the input waveguide, a drain electrode coupled to the output waveguide, and a source electrode coupled to the input ground plane. An output ground strap spaced from the drain electrode couples the output ground plane to the source electrode. A pair of transmission lines are orthogonally connected to and extend from the gate electrode to form a pair of inductors for matching the impedances of the gate electrode and the input waveguide.
A semiconductor device that has a structure wherein plural incremental circuits each of which is structured by a combination of a field effect transistor and a transmission line are connected and arranged in serial, in the arrangement of the above incremental circuits, the total length of the transmission lines of respective incremental circuits is longer than at least 1/16 of a wavelength of used microwave or millimeter-wave, and the number of arranged incremental circuits is numerous, as a result, the above transmission lines have a function as a distributed-constant line.
Three or more MESFETs are fabricated side by side on a semiconductor chip. A transmission line substantially identical in width with an area within which the MESFETS are fabricated is formed in parallel with the row of MESFETs. The MESFETs are connected to the transmission line at a side, constituting one edge of the transmission line. Further, regulation circuits are connected in shunt with the transmission line, and outputs of the MESFESTS are merged while being matched by the transmission line and the regulation circuits.
