Abstract: An RF power amplifier linearizer uses a switched distortion power-minimization routine, or simultaneous correlation and power-minimization routines to adjust operational parameters of a vector modulator and a predistortion operator feeding the RF amplifier. The switched power-minimization routine controls the vector modulator, and then adjusts coefficients of the predistorter using the same power minimization routine. The continuous correlation and power minimization routine adjusts the predistortion unit by means of a power minimization unit, and uses a correlator based control mechanism to control the vector modulator simultaneously with the power minimization routine's control of the predistortion unit.

Abstract: To avoid VSWR degradation associated with using a fixed impedance matching transformer in an RF power amplifier combiner, the transformer is configured as an adjustable-impedance matching transformer, that maintains a relatively low voltage standing wave ratio at the combiner's output port, as the number of amplifiers is changed. The adjustable impedance transformer may comprise a section of transmission line conductor and an adjacent dielectric medium, the dielectric constant of which is controllably variable. The dielectric medium may comprise a shaped dielectric element, that is positionable relative to the transmission line conductor, so as to provide a variable dielectric constant and thereby allow the effective impedance of the transformer to be varied among respectively different values based upon the number of amplifiers being combined.

Abstract: A hybrid multicarrier RF power amplifier linearization architecture combines ACT and feed-forward amplifier stages to achieve high output distortion rejection and enhanced amplifier linearity. A carrier cancellation loop is coupled with a main RF power amplifier stage having parallel RF power amplifiers coupled via intermod-complementing predistortion paths. The carrier cancellation loop is coupled to a feed-forward loop containing a feed-forward RF power amplifier, to produce a composite amplified output signal having very reduced intermodulation products. Vector modulators in the main amplifier and feed-forward amplifier stages are controlled by a digital signal processor, using outputs from various monitoring subsystems, including pilot tone detection, correlator, distortion and power detector circuits.

Abstract: A digitally-based high distortion rejection scheme for linearizing an RF power amplifier employs a digital signal processor, which executes a first signal processing operator in terms of a digital polynomial-based predistortion function that approximates an inverse of the dynamic memory effects in the nonlinear transfer characteristic of the amplifier, and a second signal processing operator that represents an inverse of static non-linearities in the transfer characteristic of the amplifier. The output of this cascaded filter operation is used to control parameters of a vector modulator in the signal input path to the RF power amplifier. The vector modulator thus predistorts the RF input signal, so as to compensate for dynamic memory effects and static non-linearities in the power amplifier.

Abstract: A printed circuit architecture includes a relatively thick, stiffening base of thermally and electrically conductive material, and a laminate of conductive layers including a printed circuit structure, interleaved with dielectric layers, disposed atop the base. The patterned conductive layers contain an integrated circuit structure that is configured to provide RF signaling, microstrip shielding, and digital and analog control signal leads, and DC power. Low inductance electrical connectivity among the conductive layers and also between conductive layers and the base is provided by a plurality of conductive bores. Selected bores are counter-drilled at the RF signaling layer and filled with insulating plugs, which prevent shorting of the RF signal trace layer to ground, during solder reflow connection of leads of circuit components to the RF signaling layer.

Abstract: A closed loop, active cancellation technique (ACT)-based RF power amplifier linearization architecture injects a pilot tone as a ‘pseudo distortion’ signal into signal paths through first and second matched RF amplifiers, and a set of power minimization loops are closed around the RF amplifier pair. The power minimizing control loops control a set of vector modulators such that both the injected pilot tone and intermodulation distortion products are canceled, while RF carrier components constructively sum in the composite output of the two RF amplifiers.

Abstract: A printed circuit architecture includes a relatively thick, stiffening base of thermally and electrically conductive material, and a laminate of conductive layers including a printed circuit structure, interleaved with dielectric layers, disposed atop the base. The patterned conductive layers contain an integrated circuit structure that is configured to provide RF signaling, microstrip shielding, and digital and analog control signal leads, and DC power. Low inductance electrical connectivity among the conductive layers and also between conductive layers and the base is provided by a plurality of conductive bores. Selected bores are counter-drilled at the RF signaling layer and filled with insulating plugs, which prevent shorting of the RF signal trace layer to ground, during solder reflow connection of leads of circuit components to the RF signaling layer.

Abstract: A closed loop, active cancellation technique (ACT)-based RF power amplifier linearization architecture injects a pilot tone as a ‘pseudo distortion’ signal into signal paths through first and second matched RF amplifiers, and a set of power minimization loops are closed around the RF amplifier pair. The power minimizing control loops control a set of vector modulators such that both the injected pilot tone and intermodulation distortion products are canceled, while RF carrier components constructively sum in the composite output of the two RF amplifiers.

Abstract: An ‘orthogonally stacked’ support and cooling architecture for RF signaling circuits includes a plurality of RF amplifier circuit cards mounted on edge-mountable RF printed circuit support and heat dissipation modules, that are affixed to a first side of a base plate, so that the RF circuit cards extend in a direction that is generally orthogonal to the base plate. Arranged on a second side of the base plate are RF distribution networks for the RF circuit cards. The RF signal distribution networks are RF-coupled to the RF printed circuit boards by blind-mating, square post type multi-pin connectors through the base plate. Orienting the RF distribution networks in a plane orthogonal to the RF circuit cards and having the heat exchangers extend into gaps between the modules serves to considerably reduce the size of the architecture.

Abstract: RF power amplifier distortion can be accurately measured in the presence of multi-frequency input signals, by using a swept local oscillator to tune RF input and output receivers. The power detected by the input receiver is compared with a threshold associated with the carrier. Whenever the power detected by the input receiver exceeds the threshold—indicating that the input receiver is tuned on carrier energy—the signal path through the output receiver is blanked. The sweeping action combined with selective blanking of the output receiver creates an adaptive notch filter, which allows for the direct measurement of low level distortion power in the presence of high power carriers. This distortion power is digitized and can be processed to control pre-distortion correction circuitry or gain/phase adjustment circuitry of a feed-forward error correction loop.

Abstract: An ‘orthogonally stacked’ support and cooling architecture for RF signaling circuits includes a plurality of RF amplifier circuit cards mounted on edge-mountable RF printed circuit support and heat dissipation modules, that are affixed to a first side of a base plate, so that the RF circuit cards extend in a direction that is generally orthogonal to the base plate. Arranged on a second side of the base plate are RF distribution networks for the RF circuit cards. The RF signal distribution networks are RF-coupled to the RF printed circuit boards by,blind-mating, square post type multi-pin connectors through the base plate. Orienting the RF distribution networks in a plane orthogonal to the RF circuit cards and having the heat exchangers extend into gaps between the modules serves to considerably reduce the size of the architecture.

Abstract: Performance of an RF power bipolar transistor having a collector region, at least one base region, and a plurality of elongated emitter fingers in each major region, is enhanced by forming each emitter finger with at least two spaced segments and contacting the two spaced segments with a metal lead. By eliminating the middle portion of each emitter finger, current hogging at the central portion and hot spot generation are eliminated. Power output is maintained with reduced emitter lengths by minimizing the adverse affects of the hot spot generation in the emitters.

Abstract: RF power amplifier distortion is measured in the presence of multi-frequency input signals, by sweeping a local oscillator to tune RF input and output receivers. When the power detected by the input receiver exceeds a carrier energy threshold, the operation of a predistortion processor is blanked. This creates an adaptive notch filter, which allows for the direct measurement of low level distortion power in the presence of high power carriers. The unnecessary complexity of using controllably interrupted high isolation switches in the signal flow path of the output receiver in certain applications may be effectively obviated by buffer amplifier—passband filter stages. These buffer-filter stages provide additional gain to offset the fact that the signal level extracted from the output amplifier is very low, and prevent producing IMDs in the swept receiver's mixer. They are preferably implemented of the same bandpass filter in the swept input receiver.

Abstract: RF power amplifier distortion can be accurately measured in the presence of multi-carrier input signals, by using a common swept local oscillator to tune RF input and output receivers, whose outputs are monitored for distortion correction purposes. In carrier cancellation and feedforward cancellation mode, when the power detected by the input receiver exceeds a power threshold, the processor accumulates a digital representation of uncancelled carrier energy detected by the output receiver when sampling the signal at the output of the carrier cancellation combiner. It otherwise accumulates uncancelled IMD sampled at the output of the amplifier downstream of the feedforward cancellation coupler. In predistortion mode, the output receiver monitors only the output of the carrier cancellation combiner. When the power detected by the input receiver does not exceed the carrier power threshold, any energy measured by the output receiver corresponds to residual distortion energy from the predistorted main amplifier.

Abstract: RF power amplifier distortion is measured in the presence of multi-frequency input signals, by sweeping a local oscillator to tune RF input and output receivers. When the power detected by the input receiver exceeds a carrier energy threshold, the operation of a predistortion processor is blanked. This creates an adaptive notch filter, which allows for the direct measurement of low level distortion power in the presence of high power carriers. The unnecessary complexity of using controllably interrupted high isolation switches in the signal flow path of the output receiver in certain applications may be effectively obviated by buffer amplifier—passband filter stages. These buffer-filter stages provide additional gain to offset the fact that the signal level extracted from the output amplifier is very low, and prevent producing IMDs in the swept receiver's mixer. They are preferably implemented of the same bandpass filter in the swept input receiver.

Abstract: RF power amplifier distortion can be accurately measured in the presence of multi-frequency input signals, by using a swept local oscillator to tune RF input and output receivers. The power detected by the input receiver is compared with a threshold associated with the carrier. Whenever the power detected by the input receiver exceeds the threshold—indicating that the input receiver is tuned on carrier energy—the signal path through the output receiver is blanked. The sweeping action combined with selective blanking of the output receiver creates an adaptive notch filter, which allows for the direct measurement of low level distortion power in the presence of high power carriers. This distortion power is digitized and can be processed to control pre-distortion correction circuitry or gain/phase adjustment circuitry of a feed-forward error correction loop.

Abstract: A hybrid multicarrier RF power amplifier linearization architecture combines ACT and feed-forward amplifier stages to achieve high output distortion rejection and enhanced amplifier linearity. A carrier cancellation loop is coupled with a main RF power amplifier stage having parallel RF power amplifiers coupled via intermod-complementing predistortion paths. The carrier cancellation loop is coupled to a feed-forward loop containing a feed-forward RF power amplifier, to produce a composite amplified output signal having very reduced intermodulation products. Vector modulators in the main amplifier and feed-forward amplifier stages are controlled by a digital signal processor, using outputs from various monitoring subsystems, including pilot tone detection, correlator, distortion and power detector circuits.

Abstract: A carrier cancellation combiner, and pre-distortion and feed-forward loops of an RF power amplifier are controlled to minimize IMD components at the output of the RF amplifier, by a spectral distortion measurement scheme that performs Fast Fourier Transform (FFT)-based spectral power measurements at a ‘reference’ signal port (associated with the RF input signal), and a plurality of ‘test’ signal ports (associated with various monitoring locations of the amplifier). Signals extracted from the control and test ports are downconverted to baseband, bandpass filtered, digitized and stored as a spectral ‘snapshot’ of the entire band of the signal infrastructure of the amplifier. A digital signal processor-based controller processes the buffered data to produce averaged FFT's of the data extracted from the reference and test ports and thereby provide spectral information for each sampled signal set.

Abstract: A current mirror bias circuit for an RF amplifier transistor is modified whereby the reference transistor of the current mirror tracks hot carrier degradation in the RF transistor. Gate bias to the current mirror transistor is modified whereby the drain-to-gate voltage can be positive, and the lightly doped drain region in the lateral n-channel reference transistor is shortened and dopant concentration increased to increase the electric field of the reference transistor to provide the hot carrier injection degradation characteristics similar to the main transistor. Additionally, the gate length of the reference transistor can be shortened to effect the hot carrier injection degradation.

Abstract: Linearity of an RF/microwave power amplifier is enhanced by an amplitude and phase distortion correction mechanism based upon signal envelope feedback, that operates directly on the RF signal passing through the power amplifier. A phase-amplitude controller responds to changes in gain and phase through the RF/microwave power amplifier signal path caused by changes in RF input power, DC power supply voltages, time, temperature and other variables, and controls the operation of a gain and phase adjustment circuit, so as to maintain constant gain and transmission phase through the RF/microwave power amplifier.