Abstract: A circuit can include an amplifier having at least a first junction field effect transistor (JFET) of a first conductivity type with a source coupled to a first power supply node, and a drain coupled to an amplifier output node. A first variable bias circuit can be coupled between the drain and at least one gate of the first JFET. The first variable bias circuit can alter a direct current (DC) bias to the first JFET according a potential at the amplifier output node. A first bias impedance can be coupled between the drain of the first JFET and a second power supply node. The circuit can also include a non-linear transmission line (NLTL) coupled between the amplifier output and a gate of the first JFET. The NLTL being configured to propagate an electrical soliton.
Abstract: A quadrature transmitter and receiver have configurable I and Q channel paths that facilitate the application of selected test signals to determine gain and phase imbalances introduced by the transmitter and receiver. In a first ‘normal’ configuration, the I and Q channels are independently tested by applying an I-only test signal, followed by a Q-only test signal. In a second ‘switched transmitter’ configuration, the Q-only test signal is again applied. In a third ‘switched receiver’ configuration, the I-only test signal is again applied. By combining the results, gain and phase imbalances of the transmitter and the receiver can be determined. In a preferred embodiment, these configurations and test signals are applied within a single transceiver that has the output of its transmitter closed-loop coupled to the input of its receiver.
Abstract: An electrical generator that uses a high frequency oscillator in a tuned circuit, set to resonate with the transmitter coil of a full-length high frequency transformer unit, to generate electromagnetic energy, to transform this energy to electrical energy and to collect this energy.
Abstract: Methods and apparatus for implementing stable self-starting and self-sustaining electrical nonlinear pulse (e.g., soliton, cnoidal wave, or quasi-soliton) oscillators. In one example, a nonlinear pulse oscillator is implemented as a closed loop structure that comprises a nonlinear transmission line, an improved high-pass filter, and a nonlinear amplifier configured to provide a self-adjusting gain as a function of an average voltage of the oscillator signal, to provide a pulse waveform having a desired target amplitude. In one implementation, the nonlinear amplifier and high pass filter functions are integrated in a two stage nonlinear amplifier/filter apparatus employing complimentary NMOS and PMOS amplification components and associated filtering and feedback circuitry configured to essentially implement an electric circuit analog of a saturable absorber via an adaptive bias control technique.
September 8, 2005
Date of Patent:
March 4, 2008
President and Fellows of Harvard College
David Ricketts, Xiaofeng Li, Donhee Ham
Abstract: A discrete monotron oscillator for use in a high power microwave device is formed with a microwave oscillator having a half-wavelength resonant coaxial microwave cavity operating in fundamental TEM mode for microwave oscillation with an inner conductor defining a drift tube for propagating an electron beam and an outer conductor coaxial with the inner conductor. The inner conductor defines a modulating gap and an extraction gap downstream of the modulating gap. The modulating gap and the extraction gap connect the coaxial microwave cavity with the drift tube so that energy for the microwave oscillation is extracted from the electron beam at the extraction gap and modulates the electron beam at the modulating gap. For high power operation, an annular electron beam is used.
December 8, 1995
Date of Patent:
February 3, 1998
The Regents of the University of California
Abstract: An option select scheme (300) and circuit (200) allows a single analog-to-digital (A/D) line (211) to be used between an accessory (204) and a portable radio (202) to control first and second accessory features (234, 236). First and second variable resistive devices (226,228) are used in conjunction with a push-to-talk switch (PTT) (230) to control the first and second accessory features (234, 236). The PTT switch (230) allows the first variable resistive device (226) to present a first voltage range to the A/D line (211) in a first state when the PTT switch (230) is depressed. The PTT switch (230) allows the second variable resistive device (228) along with bias resistor (224) to present a second voltage range to the A/D line (211) in a second state when the PTT switch (230) is not depressed. A third state exists when the accessory (204) is disconnected from the radio (202) and a third voltage range is presented to the A/D line (211).
Abstract: High-frequency, low-power CMOS oscillators having electrically-tunable tank circuits are disclosed. Electrically-tunable inductors assure highly efficient oscillator operation and can be adjusted after manufacture to assure high yields of high-precision oscillator circuits.