An amplifying apparatus for linearly amplifying a desired signal using a pair of coupled non-linear amplifiers is disclosed. The amplifying apparatus comprises a limiter for separating amplitude variations from the desired signal and producing a constant amplitude signal bearing the phase of the desired signal and an amplitude related signal. In addition, a drive signal generater produces two drive signals each dependent on the constant amplitude signal and the amplitude related signal such that each drive signal depends on the phase of the desired signal and such that the sum of the squares of the amplitudes of the drive signals is constant. Finally, a coupler couples the two drive signals to produce two constant amplitude signals for driving the pair of non-linear power amplifiers and for coupling the outputs of the power amplifiers to produce two amplified output signals, one of which is the linearly amplified desired signal and the other of which is a waste energy signal.

Waste energy control and management in power amplifiers

A variable-class linear amplifier (600, 800, 900) applies a supply type of envelope modulation to an RF power amplifier operating in or near compression at highest envelope amplitudes, and transitions gradually to an envelope tracking type of operation at intermediate envelope amplitudes. The amplifier further transitions gradually to a linear class of operation with a constant supply voltage (508) at lowest envelope amplitudes.

Method and apparatus for operating a radio-frequency power amplifier as a variable-class linear amplifier

A petroleum well has an electronic module and a number of sensors which communicate with the surface using the tubing string and casing as conductors. Induction chokes at the surface and downhole electrically impede AC flow through the (tubing or casing if so configured) with the resulting voltage potential useful for power and communication. A high bandwidth, adaptable spread spectrum communications system is used to communicate between the downhole electronics module and a surface master spread spectrum modem. Downhole sensors, such as pressure, temperature, acoustic and seismic sensors accurately assess downhole physical conditions. In a preferred form, the electronics module and sensors are wireline insertable and retrievable into a side pocket mandrel in the tubing string. Permanent downhole sensors that can communicate with the surface allow such diverse applications as optimizing well and field performances, monitoring and assessing the geophysics of the fomrations around the well, assessing well and reservoir reserves, assessing reservoir conditions.

Petroleum well having downhole sensors, communication and power

The present invention, generally speaking, provides for high-efficiency power control of a high-efficiency (e.g., hard-limiting or switch-mode) power amplifier in such a manner as to achieve a desired modulation. In one embodiment, the spread between a maximum frequency of the desired modulation and the operating frequency of a switch-mode DC-DC converter is reduced by following the switch-mode converter with an active linear regulator. The linear regulator is designed so as to control the operating voltage of the power amplifier with sufficient bandwidth to faithfully reproduce the desired amplitude modulation wave-form. The linear regulator is further designed to reject variations on its input voltage even while the output voltage is changed in response to an applied control signal. This rejection will occur even though the variations on the input voltage are of commensurate or even lower frequency than that of the controlled output variation. Amplitude modulation may be achieved by directly or effectively varying the operating voltage on the power amplifier while simultaneously achieving high efficiency in the conversion of primary DC power to the amplitude modulated output signal. High efficiency is enhanced by allowing the switch-mode DC-to-DC converter to also vary its output voltage such that the voltage drop across the linear regulator is kept at a low and relatively constant level. Time-division multiple access (TDMA) bursting capability may be combined with efficient amplitude modulation, with control of these functions being combined. In addition, the variation of average output power level in accordance with commands from a communications system may also be combined within the same structure.

High-efficiency modulating RF amplifier

A system and method of communicating among devices via a piping structure using at least one induction choke about the piping structure to route a time-varying current carrying communication signals between the devices. A communications system comprises a piping structure, a first communication device, a second communication device, and an induction choke. The piping structure comprises a first location, a second location, and an electrically conductive portion extending between the first and second locations. The first and second locations are distally spaced along the piping structure. The first and second communication devices are each electrically connected to the electrically conductive portion of the piping structure along the first location and second location, respectively, and each is adapted to send and receive communication signals via time-varying current. The induction choke is located about an electrically choked portion of the electrically conductive portion of the piping structure, such that the induction choke is adapted to route time-varying current within the piping structure between the electrical connection location for the first communication device and the electrical connection location for the second communication device, and such that the first communication device can communicate with the second communication device via the piping structure. A preferred application of the present invention is a well for producing petroleum products (e.g., oil, natural gas), comprising a communication system as described above.

Permanent downhole, wireless, two-way telemetry backbone using redundant repeaters

A method (200) and device (100) provide an efficient linear power amplifier that generates a variable-envelope radio frequency RF signal. The method includes the steps of: A) using an efficient envelope-following unit to output a supply voltage in accordance with a variable envelope of an input baseband signal, wherein using the efficient envelope-following unit includes: 1) using a bandwidth-limiting mapping unit to determine a reference signal based on the baseband signal; and 2) using an envelope-tracking power converter to output a supply voltage, responsive to the reference signal, to the linear RF power amplifier; B) providing an RF input signal with amplitude and phase information to a linear RF power amplifier; and C) using the linear RF power amplifier to output a power-efficient amplified variable-envelope RF signal with substantially a same amplitude and phase information as the RF input signal.

Method, device, phone and base station for providing envelope-following for variable envelope radio frequency signals

The present invention provides a linearization system (100) and method (700, 800) for generating a predistorted drive signal for a nonlinear transmission path. The linearization includes: A) an analog feedback system (39), coupled to a computation unit, for determining, during a training mode, a complex error signal that linearizes the nonlinear transmission path and wherein, in an operation mode, the analog feedback system is disabled; and B) a computation unit (1), coupled to the analog feedback system and coupled to receive a complex input signal and the complex error signal, for determining, during the training mode, complex predistortion gain coefficients and, during the operation mode, generating the predistorted drive signal for the nonlinear transmission path, wherein the analog feedback system and computation unit are interconnected by interface circuitry.

Predistortion system and method using analog feedback loop for look-up table training

A transceiver (10) in a first embodiment includes a zero intermediate frequency (ZIF) receiver (11), which achieves high throughput operation by reducing receiver latency time due to receiver response within a receiver pass band to carrier spectral components of a modulated carrier frequency. During a receive mode, a receiver local oscillator (LO) frequency is offset from the carrier frequency within the receiver pass band, preferably as determined by worst case errors in the carrier frequency and the LO frequency. During a transmit mode, the receiver LO frequency is modulated in such a way as to suppress the LO center frequency component in the modulated spectrum.

Method and apparatus for improved zero intermediate frequency receiver latency

An adaptive predistortion linearization system includes input path digital-to-analog converters (DACs), error path DACs, a digital signal processor, and a radio frequency (RF) combiner. The digital signal processor includes a look-up table storing complex gain coefficient values. The digital signal processor generates an error signal based on the complex input signal and the complex gain coefficients by using a vector decomposition calculation. Feedback from a power amplifier can be provided to a training algorithm for periodically updating the gain coefficient values stored in the look-up table. By performing separate D/A conversions, the error path and input signals can be separately filtered. This separation also permits the error signal to be decoupled from the complex input signal, which facilitates an improvement in the wide-frequency-offset noise performance of the system.

Amplifier predistortion system and method

A variable pattern antenna system including a plurality of radiating elements, a switching circuit for selectively applying signals to various ones of the radiating elements, a phase shifting circuit for shifting the phase of the signals applied to the elements, and a control circuit for operating the switching circuit and phase shifting circuit to cause variable phase signals to be applied to predetermined radiating elements for changing the pattern of the antenna, and a drive wave-shaping circuit to prevent abrupt switching and the spectrum spreading interference commonly known as ''''splatter'''' that would occur.

George Francis Opas

Papers

Method, device, phone and base station for providing envelope-following for variable envelope radio frequency signals

Predistortion system and method using analog feedback loop for look-up table training

Method and apparatus for improved zero intermediate frequency receiver latency

Amplifier predistortion system and method

Antenna pattern generator and switching apparatus