132results about "Amplifiers with transit-time effect" patented technology

A traveling wave device employs an active Gallium Nitride FET. The Gallium Nitride FET has a plurality of gate feeding fingers connecting to an input gate transmission line. The FET has a drain electrode connected to an output drain transmission line with the source electrode connected to a point of reference potential. The input and output transmission lines are terminated with terminating impedances which are not matched to the gate and drain transmission lines. The use of Gallium Nitride enables the terminating impedance to be at much higher levels than in the prior art. The use of Gallium Nitride permits multiple devices to be employed, thus resulting in higher gain amplifiers with higher voltage operation and higher frequency operation. A cascode traveling wave amplifier employing GaN FETs is also described having high gain and bandwidth.

An inductive output tube (IOT) provides improved efficiency and larger bandwidth. In one embodiment, an IOT is provided with an electron gun that generates an electron beam, a tube body, a collector for collecting the electron beam, and an extended-interaction output circuit. The electron beam travels through the tube body and the extended-interaction output circuit. The extended-interaction output circuit is located within the tube body. The extended-interaction output circuit comprises a short-circuited resonant structure. The extended-interaction output circuit is used for reducing undesired components of a radio frequency (RF) wave, increasing desired components of the RF wave, and slowing down the propagation of the RF wave. (That is the circuit increases the integral of the electric field along the path of the beam electrons while decreasing the stored energy associated with those fields.) The extended-interaction output circuit also provides the IOT with larger bandwidth operation. The collector may be a multi-stage depressed collector having voltages on the collector to result in a constant efficiency characteristic. The radio-frequency drive power to the tube is connected by means of a broadband impedance matching transformer, and the grid to cathode capacitance may be reduced by depressions in the surface of the cathode directly underneath the grid structure.

A method and apparatus for reducing imbalances among the outputs of a plurality of driver devices connected in a parallel configuration to drive a common load. One driver is designated as the master, and suitable servo circuitry is provided to each of the other slave drivers, each servo being operative to force the output of its associated slave driver to accurately track the output of the designated master driver. The servo circuitry may be disposed to equalize either the output voltages or output currents of the several drivers to ensure load balancing among the drivers, to reduce cross-conduction currents and attendant power wastage and improve dynamic performance. The plurality of drivers may either operate in an open-loop configuration, or be enclosed within an overall negative feedback loop under the control of a separate controller that itself may be an amplifier.

A power supply apparatus for a traveling-wave tube includes an electrical discharge switch and a first resistor that are serially connected, and that are connected between a cathode electrode and a first collector electrode; N (N denotes a positive integer) arresters that are serially connected, and that are inserted between a ground potential and a connection node of the electrical discharge switch and the first resistor; N second resistors that are inserted between the N arresters and a second collector electrode to an Nth collector electrode and a ground potential, respectively; and an electrical discharge control circuit that turns off the electrical discharge switch at a time of normal operation of the power supply apparatus and turns on the electrical discharge switch when stopping operation of the power supply apparatus.

Disclosed herein is a class of mm and sub mm wavelength amplifiers and oscillators operating with miniature helical slow wave circuits manufactured using micro fabrication technology. The helices are supported by diamond dielectric support rods. Diamond is the best possible thermal conductor, and it can be bonded to the helix. The electron beam is transmitted, not through the center of the helix, but around the outside. In some configurations the RF power produced may be radiated directly from the slow wave circuit. The method of fabrication, which is applicable above 60 GHz, is compatible with mass production.

A traveling wave amplifier (TWA) comprising two or more amplification modules, the inputs of adjacent amplification modules being connected together by a first inductance component of a first characteristic impedance, a second inductance component of a second characteristic impedance and a third inductance component of substantially the first characteristic impedance, the first characteristic impedance being greater than the second characteristic impedance. The outputs of adjacent modules may be similarly connected together by first, second and third inductance components. The characteristic impedance of the second inductance components is preferably substantially equal to that of the circuits to which the TWA is connected, e.g. 50Ω. The first and third inductance components have a characteristic of 100Ω. Such a TWA allows balancing of phase velocities between inputs and outputs of the amplification modules, connection of these around via holes, and extends the frequency capability of the TWA.

Techniques for measuring the carrier to noise ratio (CNR) in a received digital signal are disclosed. The methods can operate on a received digital signal, such as a layered modulation signal used in a satellite television system. The CNR measurement can be made at the output of a carrier recovery loop or a timing recovery loop in a demodulator. Alternately, the CNR measurement can be made when the received signal is digitized in an analog to digital (A / D) converter at base-band by the demodulator.

Methods and apparatus are provided for stabilizing the phase and gain of an amplifier in a power pooling arrangement. A pilot signal combining a reference carrier frequency with a reference sideband frequency is passed through the amplifier via an adjustable phase shifter and an adjustable attenuator in the amplifier input line. A portion of the amplified pilot signal is coupled from the output of the amplifier and mixed with the reference frequency. The remaining audio frequency signal is compared to a reference (input) audio signal to determine phase and gain changes during amplification in the amplifier. Phase and gain control signals are developed from this comparison, and are fed back to the adjustable phase shifter and adjustable attenuator, respectively, in order to compensate an incoming signal for phase and gain variations in the amplifier.

The present invention relates to the formation of a vacuum electronics circuit by the fusion bonding of multiple substrate wafers, e.g., silicon, copper, or other suitable conductive material, each etched using DRIE, cut using EDM, or machined by other suitable means. Other aspects of the invention relate to the alignment of a cathode with tube by fusion bonding the cathode wafer to a tube built using the fabrication methods described herein. Yet other aspects involve the alignment of dies or wafers during the fabrication of a vacuum electronics device using the “lego” technique outlined herein. In yet other aspects, fabrication methods are described.

A high-power microwave generator employing a plurality of inexpensive commercial magnetron tubes cross-coupled by means of a secondary coupling path between each magnetron output pair, whereby a portion of the output energy from a first magnetron tube is injected into a second magnetron tube and a portion of the output energy from the second magnetron tube is similarly injected into the first magnetron tube. The resulting cross-injection of microwave energies brings the respective magnetron tube pair into a phase-lock sufficiently stable to permit coherent combination of their outputs for many high-power microwave applications, such as directed energy weapon systems. The magnetron phase-locking system requires no external components other than the secondary coupling paths of this invention.

A method, apparatus, article of manufacture, and a memory structure provide the ability to determine an input operating point and an output operating point on a non-linear traveling wave tube amplifier (TWTA). The non-linearity of the TWTA is measured. An input roots mean-square (RMS) value of an input signal used to measure the non-linearity of the TWTA is computed. The RMS value identifies an input operating point of the measured non-linearity of the TWTA. Lastly, an output operating point is obtained.