Abstract: A fast search algorithm for loop alignment of a feed forward amplifier is disclosed. The algorithm controls a processor that adjusts, digitally, the gain and phase of the loop alignment based on power measurements at the input and output of cancellation combiners, to find the optimal setting. A “non-collinear descent” algorithm is used to search, iteratively, for the minimum within an error surface. For loop alignment, the error surface is defined by the set of measurement points comprising the alignment settings and the associated cancellation residuals. For the case of first loop alignment, the cancellation residual is measured using the ratio of two power detectors located at the input and after the cancellation (error) combiner. For second loop alignment, cancellation is estimated using the residual pilot power detected at the output of the amplifier. The preferred alignment method uses three successive measurements to estimate the gradient direction with respect to gain and phase shifter settings.

Abstract: A system and method of correcting memory effects present within power amplifiers using digital predistortion and an improved power amplifier system employing digital predistortion are disclosed. Nonlinearities within a power amplifier having an input derived from a digital signal are compensated by injecting a digital correction signal prior to the power amplifier. A system and method for modeling the distortion created by power amplifier memory effects and generating the desired digital predistortion correction signal are disclosed.

Abstract: A delay mismatched feed forward amplifier system employing a control system and method using floors and penalties is disclosed. The disclosed control system and method allows the second loop phase adjuster setting to be offset in a repeatable and controlled manner. Applying floors and penalties to offset the steady-state phase adjuster setting modifies the conventional pilot cancellation approach. In the conventional case, pilot cancellation has a distinct minimum that corresponds to the desired adjustment setting. In the disclosed approach, the measured pilot cancellation is clipped to a lower bound or floor to produce a set of equal valued minimum control results. The floor is selected to place a desired phase offset to the phase adjuster at the edge of minimum floor. To ensure that the correct phase adjuster offset is selected from the set of equal valued minimum control results, a control direction based penalty is added.

Abstract: A method for aligning a feed forward radio frequency power amplifier includes applying a radio frequency signal to the feed forward radio frequency power amplifier and monitoring a radio frequency signal from the feed forward radio frequency power amplifier, without opening a break point of the feed forward radio frequency amplifier.

Abstract: A pilot generation and detection system within a feed forward power amplifier that uses positive feedback to create a narrow bandwidth limit cycle is disclosed. The pilot system adjusts its frequency automatically to keep a desirable phase relationship between the pilot generation and detection. As a result, quadrature modulation/detection of the pilot used in prior approaches to ensure reliable estimates of the detected pilot power is unnecessary. This reduces the cost of the system. In addition, the pilot system turns the pilot amplitude ‘on’ or ‘off’ as needed. When the alignment of the second loop is good, the positive feedback will not have sufficient gain to maintain a limit cycle. As a result, the pilot will turn off when the second loop has converged. The pilot will return automatically as a by-product of the positive feedback if the second loop alignment degrades. Turning off the pilot when the second loop has converged reduces the pilot spurs appearing at the output of the feed forward amplifier.

Abstract: Base station transmitter signals are combined more effectively through the use of anti-phase pilots between pairs of transmission paths. At the combiner, the pilots will cancel when the amplitude, phase, and delay of the two transmission paths entering the combiner are matched. As a result, the pilots will not appear at the output except when the alignment is incorrect. By detecting the residual pilot at the combiner output, the information is used to adjust the alignment of one of the transmission paths to match the other. The adjustments to the amplitude, phase, and delay are performed on the input signal, after the pilot injection.

Abstract: Methods of assembling a coupler are provided in which a first printed circuit board is provided, and a second printed circuit board is then surface mounted on the first printed circuit board. The first printed circuit board and the second printed circuit board are then electrically and mechanically connected to provide a coupler having a shielded region defined between the first printed circuit board and the second printed circuit board. The shielded region at least partly surrounds a coupler circuit disposed therein.

Abstract: An RF power amplifier having reduced memory effects is disclosed. This is achieved by a novel design of the DC supply feed network to achieve low impedance across video frequencies, whilst maintaining the correct RF output matching. One or more transmission zeros are provided in the bias circuit transfer function, which are positioned in the video bandwidth so as to provide low and relatively constant impedance across the video bandwidth. Also, a parallel DC feed line may be employed to reduce impedance across the video bandwidth. The reduction in memory effects allows improved performance of predistortion linearization techniques and an implementation in a feed forward amplifier employing predistortion linearization is also disclosed.

Abstract: A method and apparatus for making an inner conductor from a conductive body integrally forms a flange on one end of the conductive body. The flange is formed integral to the conductive body by flaring the end of the conductive body. The size and shape of the flange is selected to achieve a desired capacitance surface area for use in a resonator. A resonator housing that has a plurality of cavities can be provided with a plurality of conductive bodies that are inserted into holes located in a bottom wall of the resonator body and that protrude into the plurality of cavities. The resonator housing and conductive bodies are placed onto a flanging fixture to produce a flange on each conductive body of a desired size and shape to achieve a desired capacitance surface area. The plurality of conductive bodies can be simultaneously flanged and fastened to the base of the resonator housing.

Abstract: A system and method for post filtering signal peak reduction adapted for use in a multi-carrier communication system incorporating a source of a multi-carrier communication signal band limited in plural bands corresponding to the plural carriers. A first signal path receives as an input the band limited multi-carrier communication signal. A second parallel signal path includes a peak reduction calculation circuit for calculating a peak reduction correction signal and a plurality of filters providing a plurality of parallel filtering operations on the peak reduction correction signal corresponding to the plural bands to which the communication system is limited. The filtered peak reduction correction signals and delayed input signal are combined to provide peak adjusted output signals without violating the band limits of the communication signal or the modulation scheme of the communication signal.

Abstract: A group delay adjusting circuit. The group delay adjusting circuit comprises an electronically adjustable variable capacitance, and an electronically variable virtual inductor coupled in parallel to the electronically variable capacitance at a node.

Abstract: A feed forward power amplifier is disclosed which utilizes three signal cancellation loops. Loop 1 includes a main amplifier and is used to derive a carrier cancelled sample of the main amplifier output. Loop 2 includes an error amplifier used to amplify the carrier cancelled signal derived from Loop 1 operation in order to cancel distortion products generated due to the nonlinear nature of the main amplifier. Loop 2 also utilizes a very short Loop 2 delay line. A significant efficiency gain is provided due to reduced output power losses associated with the Loop 2 delay line. Lower output losses also results in lower distortion levels produced by the main amplifier. This, in turn, reduces the size and performance requirements placed on the error amplifier. A smaller and more efficient error amplifier is employed resulting in further amplifier system efficiency improvement.

Abstract: A method and apparatus for linear amplification of a modulated carrier signal or multi-carrier signal is disclosed. The linearity of the amplifier is improved by employing dynamic load line adjustments. A second current source coupled to the amplifier output load is turned on just before the amplifier reaches a nonlinear regime and reduces the effective load to prevent the amplifier allowing sufficient power to reach the nonlinear regime near saturation. The technique is particularly advantageous for amplification of a signal with large peak to average ratio.

Abstract: An RF power amplifier having reduced memory effects is disclosed. This is achieved by a novel design of the DC supply feed network to achieve low impedance across video frequencies, whilst maintaining the correct RF output matching. One or more transmission zeros are provided in the bias circuit transfer function, which are positioned in the video bandwidth so as to provide low and relatively constant impedance across the video bandwidth. Also, a parallel DC feed line may be employed to reduce impedance across the video bandwidth. The reduction in memory effects allows improved performance of predistortion linearization techniques and an implementation in a feed forward amplifier employing predistortion linearization is also disclosed.

Abstract: A delay mismatched feed forward amplifier system employing a control system and method using floors and penalties is disclosed. The disclosed control system and method allows the second loop phase adjuster setting to be offset in a repeatable and controlled manner. Applying floors and penalties to offset the steady-state phase adjuster setting modifies the conventional pilot cancellation approach. In the conventional case, pilot cancellation has a distinct minimum that corresponds to the desired adjustment setting. In the disclosed approach, the measured pilot cancellation is clipped to a lower bound or floor to produce a set of equal valued minimum control results. The floor is selected to place a desired phase offset to the phase adjuster at the edge of minimum floor. To ensure that the correct phase adjuster offset is selected from the set of equal valued minimum control results, a control direction based penalty is added.

Abstract: A system and method for signal peak reduction in a spread spectrum communication system of the type including a filter for limiting signal bandwidth of symbols transmitted from the system. A signal peak reduction unit is provided before the filter that includes a filter predictor that predicts the effect of the filter on input symbols by using filter coefficient values corresponding to the filter impulse response function. Input symbols that are predicted to cause the output signal to exceed a predetermined peak limit value are adjusted. Several examples of suitable algorithms for calculating the necessary peak reduction to be applied to the input symbols are disclosed. The peak reduction unit provides adjusted symbols to the filter for processing and communication system output.

Abstract: A feed forward amplifier employing a new adaptive controller and method is disclosed. The controller aligns both a gain adjuster and phase adjuster of a first cancellation loop. The phase adjuster may be controlled following a standard approach. However, the gain adjuster is offset intentionally causing an incomplete cancellation, increasing the signal power passing through the error amplifier. If the gain adjuster is offset low, below the gain adjustment required to maximize carrier cancellation, peak power output from the main amplifier is reduced while the second loop maintains constant system output power. If the gain adjuster is offset high, peak power output from the error amplifier is reduced while the second loop maintains constant system output power. By controlling the gain adjuster offset from full first loop cancellation, the feed forward amplifier can be optimized for the power handling capabilities of the main and error amplifiers.

Abstract: A method and apparatus for rapid alignment of adaptive feed forward power amplifiers are disclosed. Successful alignment settings are correlated with the operating conditions that affect the gain and phase of an amplifier. These operating conditions may include input power level, carrier frequency, temperature, DC supply voltage, or others. The successful alignment settings along with the corresponding operating conditions are stored in a list that is indexed using multi-dimensional attribute vectors. The elements of the list are generated automatically.

Abstract: A feedforward amplifier. The present invention therefore provides a feedforward amplifier, comprising: a pilot reference generator that generates a pilot signal; a first carrier cancellation loop; a first error amplifier loop including a first error amplifier, wherein the pilot signal is utilized to provide gain stabilization in the first error amplifier a third loop; a second carrier cancellation loop that includes a first phase and amplitude adjuster in module and a second amplitude and phase adjuster disposed between module and module, wherein the pilot signal is utilized to control the adjustment of the second carrier cancellation loop.

Abstract: A printed circuit board assembly employing a solder vent hole adjacent solder filled interconnect vias connecting to a conductive pallet, is disclosed. The solder vent hole allows gases to escape from an otherwise sealed cavity during solder reflow, relieving positive pressure and thereby allowing solder to flow into it. By providing an escape path for trapped air and gases generated during solder paste reflow, the out-gassing pressure and weight of the molten solder is sufficient to allow the solder paste to flow into the cavity.