3723results about "Amplifier modifications to reduce temperature/voltage variation" patented technology

Methods and apparatus for amplifier AM and PM predistortion and autocalibration. AM and PM amplifier distortion can be corrected using predistortion. The AM and PM distortion characteristics of the amplifier are determined using an autocalibration technique. The amplifier characteristics can be stored in distinct look up tables. Alternatively, the inverse of the amplifier characteristics can be stored in distinct look up tables. Signals that are to be amplified are characterized in polar format having a phase component with a normalized magnitude and a magnitude component. The phase component can be predistorted by applying the inverse of the PM distortion characteristics to the signal. Similarly, the magnitude component can be predistorted by applying the inverse of the AM distortion characteristics to the signal. The predistorted phase component can be amplified using the previously characterized amplifier. The predistorted magnitude component can be used to set the gain of the previously characterized amplifier.

An embodiment of the invention uses a predistortion correction signal to combination the modulated RF signal by an analog multiplier for linearization of power amplifiers having nonlinear characteristics such as those used in wireless RF transmitters. A predistortion controller comprises a plurality of down converters for retrieving both the ideal non-distorted information and the feedback distorted information, together with pre-stored digitally-indexed predistortion information stored, for example, in a look-up table. The digitally-indexed information models nonlinear characteristics of the high power amplifier, and is stored prior to processing of pre-compensation in the power amplifier. When the predistortion information is combined with the modulated RF signal in the analog multiplier, the result is a substantially linear information transmission from the power amplifier. In an embodiment of the system, the modulated RF input signal and the feedback signal from PA output are down-converted, respectively, by analog devices, such as mixers, after which the analog intermediate frequency (IF) signals are digitized by analog-to-digital converters for digital predistortion correction processing, followed by predistortion processing performed by, for example, a DSP or FPGA chip to generate a digital correction control signal, which is then converted to an analog signal by a digital-to-analog converter, followed by combining the analog correction signal with the RF modulated input signal to yield the input to the power amplifier.

The present invention includes methods and devices to apply predistortion to correct nonlinearities of a power amplifier in an OFDM symbol transmission system. More particularly, predistortion is patterned to take into account clipping of symbols and to match an effective input range of the predistorter with an average power output of the power amplifier. This invention may be applied to a variety of standards utilizing OFDM technology, including IEEE 802.11a, Hiperlan / 2 and MMAC.

Power amplifier arrangements, methods, and software arranged to receive a power input which is voltage-modulated responsive to at least one control signal representative of the data signal. The data input to the power amplifier is pre-distorted and the resulting power amplification is substantially linear. The arrangement may be used in wireless base station transmitters, but is not limited to such applications. Improved data transmission services are also provided which make use of such power amplifiers.

A power calculating and amplitude limitation judging portion 13 calculates the power value x of the digital quadrature baseband signal I, Q from a transmission data generator 1, and compares the power value x with a power threshold value y set by a threshold value setting portion 14 to judge whether amplitude limitation is needed or not. An amplitude maximum limiting portion 12 subjects the quadrature baseband signal from the transmission data generator 1 to the amplitude maximum value limitation based on the judgment result in the power calculating and amplitude limitation judging portion 13. Thereafter, the digital quadrature baseband signal which has been subjected to the amplitude maximum value limitation by the amplitude maximum value limiting portion 12 is subjected to the distortion compensation using complex multiplication based on the distortion compensation data by a non-linear distortion compensation calculator 2.

A method and an arrangement for detecting impedance mismatch between an output of a radio frequency amplifier (200, 901, 911, 921, 1101) which has an amplifying component (201, 301, Q46, 701, 801) and an input of a load (203, 302) coupled to the output of the radio frequency amplifier having: first monitoring means (401) to monitor a measurable electric effect (311) at a side of the amplifying component (201, 301, Q46, 701, 801) other than the load (203, 302) and to produce a first measurement signal (411). Second monitoring means (402) monitor a measurable electric effect (312) between the amplifying component (201, 301, Q46, 701, 801) and the load (203, 302) and produce a second measurement signal (412). Decision-making means (204, 902, 912, 923, 1102) receive said first (411) and second (412) measurement signals and decide, whether said first and second measurement signals together indicate impedance mismatch.

A transceiver comprises an amplifying circuit for amplifying an input signal to produce an output signal. A power supply is operable for varying the level of power supplied to the amplifying circuit in response to variation of an input signal envelope directed to the power supply. A processing circuit is operable for digitally detecting the input signal envelope to provide variation of the power supply level. The processing circuit is further operable for digitally delaying the digital input signal envelope to time align the power supply level with the input signal.

A digital predistortion amplifier design compensates for non-linear amplification of an input signal using predistortion techniques. The design provides a reduced noise floor by using separate digital to analog converters (DAC) to separately convert the input signal and an error correction signal. Furthermore, the input signal can be separated into two or more subbands of narrower bandwidth. Each of the subbands are converted to analog using a separate DAC. By reducing the power and / or bandwidth to be handled by any one DAC, the available levels of quantization of the DAC are applied to a lower power signal and therefore the signal to noise ratio resulting from the conversion process is improved. In addition, each digital subband is passed through a correction filter, which is driven by an adaptive control processing and compensation estimator to compensate for relative gain, phase, and delay inconsistencies between the different subbands.

The amplitude modulator comprises: an angle modulator for angle-modulating a phase signal to be inputted; a waveform shaping means in which, (1) when the magnitude of an amplitude signal to be inputted becomes smaller than a first prescribed value, a waveform of the amplitude signal is shaped so that the magnitude of the amplitude signal of the portion which becomes small becomes the first prescribed value; and / or (2) the waveform shaping means in which, when the magnitude of the amplitude signal to be inputted becomes larger than the second prescribed value which is larger than the first prescribed value, the waveform of the amplitude signal is shaped so that the magnitude of the amplitude signal of the portion which becomes larger becomes the second prescribed value; and an amplitude modulator for amplitude modulating the signal of the output of the angle modulator by the signal of the output of the waveform shaping means.

Methods and apparatus are provided for substantially reducing and / or canceling nonlinearities of any order in circuits, devices, and systems such as amplifiers and mixers. In particular, methods and apparatus are provided for substantially reducing and / or canceling third order nonlinearities in circuits, devices, and systems such as amplifiers and mixers. A first coupler is used to split an input signal into two equal-amplitude in-phase components, each component is processed by two nonlinear devices with different nonlinearities, and a final combiner, such as a 180-degree hybrid, recombines the processed signals 180 degrees out of phase and substantially reduces and / or cancels the undesired nonlinear distortion components arising due to nonlinearities in the nonlinear devices.

According to an embodiment, a method includes amplifying a signal provided by a capacitive signal source to form an amplified signal, detecting a peak voltage of the amplified signal, and adjusting a controllable impedance coupled to an output of the capacitive signal source in response to detecting the peak voltage. The controllable impedance is adjusted to a value inversely proportional to the detected peak voltage.

A predistortion circuit for a microwave amplifier and more particularly to predistortion circuit configured as a Doherty amplifier. The predistortion circuit is adapted to be coupled to a downstream Doherty amplifier to precompensate for the gain compression and phase expansion of the downstream Doherty amplifier as the input power level is increased while simultaneously reducing the intermodulation (IM) distortion. In order to provide precompensation, the precompensation circuit is operated at bias level to provide gain expansion and phase compression to cancel out the gain compression and phase expansion of the downstream Doherty amplifier to provide a higher overall linear power added efficiency (PAE).

A radio frequency amplifier module (500) has a voltage monitor (546) that monitors an input supply voltage of an input power supply (534) and an adjustable power supply (512) that accepts power from the input power supply (534) and produces an adjustable power supply output that has a controllable voltage. The radio frequency amplifier module (500) further has an amplifier (402) that is supplied by the adjustable power supply output and that amplifies a radio frequency signal. The radio frequency amplifier module (500) also has an output controller (546) that is communicatively coupled to the voltage monitor and the adjustable power supply (512). The output controller (546) controls, in response to the input source voltage, the controllable voltage of the adjustable power supply output.

An advanced adaptive baseband / RF predistorting device, which advantageously uses the concept of digital receiver technology into power amplifier (PA) linearization area. The predistorting device performs an instantaneous characterization of the PA using two digital receivers to supply its dynamic AM-AM and AM-PM transfer functions used to synthesize Look-Up Tables (LUT) which implement the complex predistortion function in order to compensate for any non-linearity and memory effects.

Systems, methods, and devices relating to the provision of deliberate predistortion to an input signal to compensate for distortions introduced by an amplifier subsystem. An input signal is received by a signal processing system which includes a predistortion subsystem. The input signal is decomposed and the fragments are then predistorted by the predistortion subsystem by applying a deliberate predistortion to the fragments. The predistorted fragments are then separately processed and recombined to arrive at the system output signal. The predistortion subsystem adaptively adjusts based on characteristics of the system output signal. Also, the predistortion subsystem is equipped with a control system that is state based—the state of the predistortion subsystem is dependent upon the prevailing conditions and, when required, the control system switches the state of the predistortion subsystem. A feedback signal, a replica of the system output signal, is used in updating lookup table entries used to determine the predistortion.

Systems and methods related to amplifier systems which use a predistortion subsystem to compensate for expected distortions in the system output signal. A signal processing subsystem receives an input signal and decomposes the input signal into multiple components. Each signal component is received by a predistortion subsystem which applies a predistortion modification to the component. The predistortion modification may be a phase modification, a magnitude modification, or a combination of both and is applied by adjusting the phase of the fragment. The predistorted component is then separately processed by the signal processing subsystem. The processing may take the form of phase modulation and amplification. The phase modulated and amplified components are then recombined to arrive at an amplitude and phase modulated and amplified output signal. The predistortion modification is applied to the components to compensate for distortions introduced in the signal by the signal processing subsystem.

A tunable constant GM circuit allows to compensate for temperature and process variations with high precision by correspondingly adjusting a resistance value and / or the ratio of transistor widths. Thus, in switched capacitor circuits the frequency behaviour, such as the settling time, may be controlled by providing a compensated bias to the transconductance amplifiers typically used in these circuits.

A feedback compensation detector for a direct conversion transmitter includes a baseband processor, a direct up-converter, an antenna, and an impairment detection and compensation feedback circuit. The baseband processor generates an in-phase (I) baseband signal and a quadrature-phase (Q) baseband signal. The direct up-converter is coupled to the baseband processor, and combines the I and Q baseband signals with an RF carrier signal to generate an RF output signal. The antenna is coupled to the direct up-converter, and transmits the RF output signal. The impairment detection and compensation feedback circuit is coupled to the RF output signal and the I and Q baseband signals. The impairment detection and compensation feedback circuit down-converts the RF output signal to generate an intermediate frequency (IF) signal, measures as least one signal impairment in the IF signal, and pre-distorts the I and Q baseband signals to compensate for the measured signal impairment.

Systems and methods relating to the provision of gain, phase and delay adjustments to signals to be used by a predistortion subsystem. A portion of an input signal is delayed by delay elements prior to being received by the predistortion subsystem. The delayed input signal portion is also received by a feedback signal processing subsystem that adjusts the gain and phase of the feedback signal based on the delayed input signal portion. The adjusted feedback signal is used, along with the delayed portion of the input signal, to determine an appropriate predistortion modification to be applied to the input signal.

Systems, methods, and devices relating to the provision of deliberate predistortion to an input signal to compensate for distortions introduced by an amplifier subsystem. An input signal is received by a signal processing system which includes a predistortion subsystem. The input signal is decomposed and the fragments are then predistorted by the predistortion subsystem by applying a deliberate predistortion to the fragments. The predistorted fragments are then separately processed and recombined to arrive at the system output signal. The predistortion subsystem adaptively adjusts based on characteristics of the system output signal. Also, the predistortion subsystem is equipped with a control system that is state based—the state of the predistortion subsystem is dependent upon the prevailing conditions and, when required, the control system switches the state of the predistortion subsystem. A feedback signal, a replica of the system output signal, is used in updating lookup table entries used to determine the predistortion.

Methods and systems for vector combining power amplification are disclosed herein. In one embodiment, a plurality of signals are individually amplified, then summed to form a desired time-varying complex envelope signal. Phase and / or frequency characteristics of one or more of the signals are controlled to provide the desired phase, frequency, and / or amplitude characteristics of the desired time-varying complex envelope signal. In another embodiment, a time-varying complex envelope signal is decomposed into a plurality of constant envelope constituent signals. The constituent signals are amplified equally or substantially equally, and then summed to construct an amplified version of the original time-varying envelope signal. Embodiments also perform frequency up-conversion.

Methods and apparatus are provided for substantially reducing and / or canceling nonlinearities of any order in circuits, devices, and systems such as amplifiers and mixers. In particular, methods and apparatus are provided for substantially reducing and / or canceling third order nonlinearities in circuits, devices, and systems such as amplifiers and mixers. A first coupler is used to split an input signal into two equal-amplitude in-phase components, each component is processed by two nonlinear devices with different nonlinearities, and a final combiner, such as a 180-degree hybrid, recombines the processed signals 180 degrees out of phase and substantially reduces and / or cancels the undesired nonlinear distortion components arising due to nonlinearities in the nonlinear devices.

Systems, methods, and devices relating to the provision of deliberate predistortion to an input signal to compensate for distortions introduced by an amplifier subsystem. An input signal is received by a predistortion subsystem which applies deliberate predistortions to the input signal to arrive at a predistorted signal. The predistorted signal is received by an amplifier subsystem which decomposes the signal, processes the decomposed signal, and then recombines the components to arrive at a system output signal. The predistortion subsystem adaptively adjusts the predistortions based on characteristics of the system output signal. A feedback signal, a replica of the system output signal, is used in updating lookup table entries used to determine the predistortion.

An apparatus for electromagnetic processing comprises a controller and a processor for receiving an input signal. The processor comprises one or more stages in communication with the controller. The controller is capable of regulating the input signal and the one or more stages to generate an output signal.

An RF generating system operates with high efficiency to supply RF output power to a plasma load. The RF generating system is capable of modulating the RF output power at frequencies up to the frequency of the RF output power while maintaining high efficiency operation. Broadband frequency modulation of the RF output power suppresses instabilities thereby minimizing unstable behavior of the plasma load.

A self-tuning variable impedance circuit provides improved performance. A variation in the power applied to the variable impedance circuit causes a corresponding change in the impedance of the circuit, resulting in improved performance. For example, the variable impedance circuit may be a matching circuit that “follows” the output power of a power amplifier, thereby increasing the power efficiency of the power amplifier.

Systems and methods relating to the provision of gain, phase and delay adjustments to signals to be used by a predistortion subsystem. A portion of an input signal is delayed by delay elements prior to being received by the predistortion subsystem. The delayed input signal portion is also received by a feedback signal processing subsystem that adjusts the gain and phase of the feedback signal based on the delayed input signal portion. The adjusted feedback signal is used, along with the delayed portion of the input signal, to determine an appropriate predistortion modification to be applied to the input signal.

Systems and methods relating to the provision of gain, phase and delay adjustments to signals to be used by a predistortion subsystem. A portion of an input signal is delayed by delay elements prior to being received by the predistortion subsystem. The delayed input signal portion is also received by a feedback signal processing subsystem that adjusts the gain and phase of the feedback signal based on the delayed input signal portion. The adjusted feedback signal is used, along with the delayed portion of the input signal, to determine an appropriate predistortion modification to be applied to the input signal.