467 results about "Linear amplifier" patented technology

A novel apparatus and method of improving the power efficiency of a digital transmitter for non-constant-amplitude modulation schemes. The power efficiency improvement mechanism of the invention leverages the high efficiency of a switched-mode power supply (SMPS) that supplies the high DC current to the transmitter's power amplifier, while compensating for its limitations using predistortion. The predistortion may be achieved using any suitable technique such as digital signal processing, hardware techniques, etc. A switched mode power supply (i.e. switching regulator) is used to provide a slow form (i.e. reduced bandwidth) of envelope tracking (based on a narrower bandwidth distorted version of the envelope waveform) such that the switching regulator can use a lower switching rate corresponding to the lower bandwidth, thereby obtaining high efficiency in the switching regulator. The resulting AM-AM and AM-PM distortions in the power amplifier are compensated through predistortion of the digital amplitude modulating signal which dictates the envelope at the PA input. Similarly, the phase modulation is also compensated prior to the PA, such that once it undergoes the distortion in the PA, the end result is sufficiently close to the desired phase.

The invention is related to methods and apparatus for controlling and adapting a digital predistortion linearizer for amplification of bandlimited signals using non-linear amplifiers. The control method advantageously permits the predistortion function applied by a predistortion entity to provide a relatively constant gain. This attribute is advantageous for operation within cellular radio systems, which often employ digital power control systems. However, the disclosed techniques can also be applicable to virtually any type of digital predistortion for which an input signal or reference signal to be amplified is predistorted in a manner that is complementary to the distortion induced by a non-linear amplifier. Embodiments of the invention advantageously enhance the practicality of using digital linearization and predistortion amplification techniques. Embodiments of the invention can automatically adjust the characteristics of a predistorted signal so that a deviation from overall linearity is compensated and subsequently reduced while maintaining a nearly constant gain attribute.

A modular ultrafast pulse laser system is constructed of individually pre-tested components manufactured as modules. The individual modules include an oscillator, pre-amplifier and power amplifier stages, a non-linear amplifier, and a stretcher and compressor. The individual modules can typically be connected by means of simple fiber splices.

An amplifier system is provided that switches between operation in a polar mode and a linear mode based on a characteristic of an input signal relative to a threshold level. The system operates as a polar amplifier in the polar mode, and as a linear amplifier in the linear mode. A mode selector controls whether polar components of the input signal are sent to a power amplifier or whether a composite signal is amplified.

An envelope tracking radio frequency (RF) power amplifier having an adaptive envelope signal processing circuit is disclosed. An RF input voltage is sampled by the adaptive envelope signal processing circuit which provides control signals to the power supply which supplies voltages to RF power devices in order to simultaneously satisfy two operating conditions: a) provide best possible efficiency of the power amplifier stages depending on the input signal characteristics and b) provide compensation for RF transistor AM-AM and AM-PM distortion compensation across the power range. In particular, the voltage control provides for constant power amplifier gain across the input signal dynamic range, thus minimizing power amplifier amplitude distortions and extending the useful power amplifier linear dynamic range up to saturation point. The power amplifier thus exhibits better linearity and efficiency than offered by conventional techniques and topologies.

An integrated circuit comprises a radio frequency (RF) power amplifier (PA) output stage; at least one amplifier stage prior to the RF PA output stage; a linear amplifier comprising a voltage feedback wherein the linear amplifier is operably coupled to a low frequency supply module such that the linear amplifier and low frequency supply module provide a combined first power supply to the RF PA output stage; and a switched mode power supply module arranged to provide a second power supply to the linear amplifier and to the at least one amplifier stage prior to the RF PA output stage.

A power supply system comprises a parallel arrangement of a linear amplifier (LA) and a DC-DC converter (CO). The linear amplifier (LA) has an amplifier output to supply a first current (II) to the load (LO). The DC-DC converter (CO) comprises: a converter output for supplying a second current (12) to the load (LO), a first inductor (L1), and a switch (SC) coupled to the first inductor (L1) for generating a current in the first inductor (L1), and a low-pass filter (FI) arranged between the first inductor (L1) and the load (LO). The low pass filter (FI) comprises a first capacitor (C1; CA) which has a first terminal coupled to the switch (SC) an a second terminal coupled to a reference voltage level (GND), and a second inductor (L2; LC) which has a first terminal coupled to the first inductor (L1) and a second terminal coupled to the load (LO). The low-pass filter further comprises, either: (i) a series arrangement of a second capacitor (C2) and a damping resistor (R2), which series arrangement is arranged in parallel with the first capacitor (C1), or (ii) a parallel arrangement of a third capacitor (CB) and a damping resistor (RB) arranged in series with the first capacitor (CA), or (iii) a series arrangement of a third inductor (L3) and a damping resistor (R3), which series arrangement is arranged in parallel with the second inductor (L2), or (iv) a parallel arrangement of a fourth inductor (LD) and a damping resistor (RD), which parallel arrangement is arranged in series with the second inductor (LC).

A power amplifier circuit whose performance is optimized by operating its stages in substantially close to a Class B mode by reducing quiescent current during low driver signal levels. As the driver signal amplitude increases, the operation of the amplifier is configured to dynamically adjust to be in a Class AB mode, thereby increasing the power efficiency of the overall circuit at kiw drive levels. A further enhancement to the power amplifier circuit includes a temperature compensation circuit to adjust the bias of the amplifier so as to stabilize the performance in a wide temperature range.

The invention relates to a composite amplifier (500) based on a main amplifier (510) and an auxiliary amplifier (520), and compensation for non-linear amplifier behavior by means of respective non-linear models (570, 575) of parasitic. In order to provide proper excitation of the non-linear models. a filter network (560) based on a linear model of the output network of the composite amplifier is provided. The linear filter network (550) basically determines ideal output node voltages, which are used as input to the respective non-linear models for generating appropriate compensation signals. The compensation signals are finally merged into the input signals of the respective sub-amplifiers (510, 520), thus effectively compensating for the effects of the non-linear parasitics.

A Switch Node Assisted Linear architecture, including a linear amplifier in parallel with a switched converter, is configurable in two tracking modes: (a) a SMAL regulator in which the amplifier sets toad voltage with an envelope tracking bandwidth, and the switched converter is configured for current assist, and (b) a Switched Mode Power Supply configuration in which the amplifier is switch-decoupled, and the switcher circuit is switched configured with an output capacitor, operable as an SMPS providing load voltage with an adaptive tracking bandwidth that is less than the envelope tracking bandwidth. Staged switching effects substantially seamless transitions between tracking modes, with the amplifier holding the load voltage at a substantially constant envelope tracking voltage (CVET): (a) for ET-AT transitions, the CVET mode enables pre-charging the output capacitor to a target AT voltage, prior to switch-decoupling the amplifier; and (b) for AT-ET transitions, CVET mode enables discharging the output capacitor.

A linear amplification with nonlinear components (LINC) power transmitter is provided. The LINC power transmitter includes a digital signal processing unit which controls the LINC power transmitter; a frequency modulation unit which modulates or converts a digital signal output from the digital signal processing unit into a radio-frequency (RF) signal; a signal amplification unit which amplifies the RF signal output from the frequency modulation unit using a gain amplifier and a power amplification module; and a direct current / direct current (DC / DC) conversion unit which controls bias of the power amplification module. Here, the DC / DC conversion unit controls a base bias and / or a collect bias of the power amplification module, and the power amplification module operates in saturation.

The present invention relates to a device and a method in a transmitter stage in a radio transmitter for modulating and amplifying an information signal for further transmission through a radio channel. The transmitter stage in the radio transmitter comprises a converting device (5) PCH, an amplifier control device (8) PAC, a power detector (13) and a power amplifier (2). Examples of the problems solved by the present invention are difficulties in reducing the power consumption, non-linearities in the output signal when using non-linear amplifiers in radio transmitters, and achieving a high signal-to-noise ratio in the output signal without connecting filter arrangements after such an amplifier. The solution according to the inventive method and device utilizes an information signal which has in earlier steps been divided in its polar components: a phase reference component signal (Ephr) and an amplitude component signal (Aamp). The phase reference component phase modulates a low noise high power signal source which has a constant amplitude. The amplitude of the obtained signal is then formed in an amplifier, which is controllable with the amplitude component signal (Aamp). Its current consumption is registered and compared to a control value for the current. The amplifier is controlled towards this control value.

A bias device that modifies the bias of a device based on an input signal to the device. The device may have a fixed bias, and the bias device can be connected in parallel with the fixed bias. The device can be an amplifier, such as a linear amplifier or a class AB amplifier. The bias device can be configured to provide maximum bias during the device's crossover time period.

A power amplification apparatus and method provide for controlling envelope modulation of a Radio Frequency (RF) signal. The power amplification apparatus includes a linear amplifier configured to receive an input signal to be amplified, and generate a linear output signal for compensating for a current ripple of an amplified signal and a switch control signal having a current obtained by dividing the linear output signal by a predetermined ratio. The power amplification apparatus also includes a switching amplifier configured to receive the switch control signal through a multi-mode resistor having a variable resistance, and generate the amplified signal. The variable resistance of the multi-mode resistor determines a switching frequency representing an operating speed of the switching amplifier, and is adjusted according to a communication mode of the input signal.

An RF amplifier comprises a power amplifier and a dual bias circuit. A dual bias circuit comprises a constant current source and a constant voltage source for biasing the power amplifier. The power may include a heterojunction bipolar transistor (HBT) or a bipolar junction transistor (BJT).

Ultra high spectral efficient Feher Keying (FK) Modulation and Demodulation (Modem), Baseband Processing (BBP), Intermediate Frequency (IF) and Radio Frequency (RF) signal generation and processing methods and implementations, including Clock Modulated (CM) and Shaped Clocked (SC) Transmitters-Receivers (transceivers) are disclosed. Additional embodiments, including Feher Quadrature Shift Keying (FQPSK) and Feher Quadrature Modulation (FQAM), in conjunction with CM and SC are also described. In the FK modulator, specified clock converted and clock shaped signal parameters are generated. These are based on the input data signal patterns and are generated by means of control signals, which are designed in the data input signal interface data signal and / or clock signal encoder units. The selectable clock signal parameters include symmetrical and non-symmetrical clock signals, shaped band-limited continuous clock signal patterns, shaped encoded clock signals, variable rise and fall time clock signals, clock signals having adjustable on and off duration, multilevel and shaped clock signals and asynchronous clock signal information transmission means, where asynchronous clocking is referenced to the incoming data source signals. The FK processors are also used in conjunction with cross-correlated FQPSK quadrature and also non quadrature modem systems as input drive signals to FM VCO based systems to SSB to VSB to DSB-SC to QAM, and FQAM and to coded systems with adaptive equalized receivers, Non Redundant Error Correction (NEC), pseudo-error monitor systems. The FK systems and FT apparatus comprises entire transceiver structures including LIN (linear) and NLA (Non Linear Amplifier) transmitter receiver, AGC, synchronization and demodulation and post demodulation signal processors.

An efficient linear amplifier according to the present invention comprises a primary amplifier for providing power to a load and an auxiliary amplifier for generating an artificial reflection signal. The artificial reflection signal may have a predetermined phase difference as compared to the output signal supplied to the load. The amplifying circuit also includes a coupler connecting the primary amplifier to the load. The coupler includes a load port connected to the load, a primary port connected to an output of the primary amplifier, and an auxiliary port connected to an output of the auxiliary amplifier such that the artificial reflection signal changes an apparent impedance of the load as seen by the primary amplifier.

A multi-mode bias modulator operating in envelope tracking mode or average power tracking mode and an envelope tracking power amplifier using the same are disclosed. The envelope tracking power amplifier includes a multi-mode bias modulator and a power amplifier. The multi-mode bias modulator generates a variable bias voltage using a linear amplifier and a switching amplifier operating in envelope tracking mode or average power tracking mode in accordance with an operation mode control signal that determines any one of envelope tracking mode and average power tracking mode. The power amplifier is biased in response to the variable bias voltage, power-amplifies a radio frequency (RF) signal, and outputs the amplified RF signal to an antenna.

A driving device for a vibration-type actuator of the present invention is a driving device for driving a vibration-type actuator disposed in a magnetically shielded room. The driving device includes a linear amplifier is configured to receive a signal based on a driving waveform for driving the vibration-type actuator and output a driving voltage to be applied to the vibration-type actuator.

A receive front-end module having one or more 2 GHz Rx paths and one or more W-CDMA Rx paths for use in a portable communication device, such as a mobile phone or a communicator device. The module comprises at least two feed points operatively connected to two electrically separate antennas for receiving communication signals. The module also comprises filters for filtering the communication signals in corresponding frequency band, and means for providing cross-band isolation. The cross-band isolation is achieved by using linear amplifiers in different signal paths, for example. Advantageously, the module comprising three signal paths so that one or more modules can be used together to achieve MIMO / diversity functionality.

An envelope tracking radio frequency (RF) power amplifier having an adaptive envelope signal processing circuit is disclosed. An RF input voltage is sampled by the adaptive envelope signal processing circuit which provides control signals to the power supply which supplies voltages to RF power devices in order to simultaneously satisfy two operating conditions: a) provide best possible efficiency of the power amplifier stages depending on the input signal characteristics and b) provide compensation for RF transistor AM-AM and AM-PM distortion compensation across the power range. In particular, the voltage control provides for constant power amplifier gain across the input signal dynamic range, thus minimizing power amplifier amplitude distortions and extending the useful power amplifier linear dynamic range up to saturation point. The power amplifier thus exhibits better linearity and efficiency than offered by conventional techniques and topologies.

An approach is provided estimating non-linear characteristics of an amplifier (such as a Travelling Wave Tube Amplifier) used to amplify a composite signal in a radio communication system. The composite signal, which includes a plurality of inbound signals overlay on an outbound signal, is sampled. The outbound signal is utilized as a training signal. Coarse estimates of the response of the amplifier is generated based on the samples of the composite signal and the training signal. Further, the interference associated with the inbound signals are removed from the estimation of the response of the amplifier by curve-fitting and estimating interference characteristics of the composite signal. An estimated response of the amplifier is thus output, and can be utilized to provide accurate non-linearity compensation and cancellation.

An apparatus linearizing and technique for linearizing a nonlinear power amplifier used in transmitters of systems for digital wireless communications. Linearization of the nonlinear amplifier is achieved by adding additional signals generated from a specification-given input data stream to the output of the nonlinear power amplifier. The invention allows use of nonlinear power amplifier, which typically enjoys a lower current consumption than that of a linear power amplifier, thus increasing the time between batteries recharges (for user transmitter equipment) and / or reducing the overall size, electric bill expenses, and cooling requirements (for network transmitter equipment). Input data, generated by a given digital wireless standard, is raised to a mathematical power by a required number and converted to RF of a transmitted signal frequency. Then all obtained RF waveforms are added with the same amplitude and the opposite phase to the spectrum of sidelobes generated by nonlinearity of a power amplifier.

A current limiting circuit for a linear regulator includes an output stage transistor and a replica transistor, which have gates coupled to receive an output voltage from a linear amplifier and sources coupled to load circuitry. A drain of the output stage transistor is coupled to a VDD supply terminal, while a drain of the replica transistor is coupled to the VDD supply terminal through a first resistor. The output stage transistor and replica transistor are operated in saturation, such that proportional currents flow through these transistors. The voltage drop across the first resistor provides a first voltage, which is applied to a second amplifier. A reference voltage is also applied to the second amplifier. When the first voltage becomes less than the reference voltage, a feedback transistor is enabled to pull down the output voltage of the linear amplifier, thereby limiting the output current supplied to the load circuitry.

A low power circuit for providing power and control signals to a low noise block converter of a satellite receiver over a single coaxial cable includes a tracking switch-mode power supply. The power and control signals have a DC voltage level selected from a plurality of DC voltage levels and are modulated by an analog AC tone signal. The switch-mode power supply provides a regulated output voltage which tracks the selected DC voltage level. The regulated output voltage provides the input voltage to an adjustable linear amplifier which generates an output voltage having the selected DC voltage level modulated by the analog AC tone signal.

An amplifier system is provided that switches between operation in a polar mode and a linear mode based on a characteristic of an input signal relative to a threshold level. The system operates as a polar amplifier in the polar mode, and as a linear amplifier in the linear mode. A mode selector controls whether polar components of the input signal are sent to a power amplifier or whether a composite signal is amplified.

The disclosed switched mode assisted linear (SMAL) amplifier / regulator architecture may be configured as a SMAL regulator to supply power to a dynamic load, such as an RF power amplifier. Embodiments of a SMAL regulator include configurations in which a linear amplifier and a switched mode converter (switcher) parallel coupled at a supply node, and configured such that the amplifier sets load voltage, while the amplifier and the switched mode converter are cooperatively controlled to supply load current. In one embodiment, the linear amplifier is AC coupled to the supply node, and the switched converter is configured with a capacitive charge control loop that controls the switched converter to effectively control the amplifier to provide capacitive charge control. In another embodiment, the amplifier includes separate feedback loops: an external relatively lower speed feedback loop may be configured for controlling signal path bandwidth, and an internal relatively higher speed feedback loop may be configured for controlling output impedance bandwidth of the linear amplifier.

Apparatus and methods configure digital predistortion linearizers for power amplification of bandlimited signals using non-linear amplifiers. The predistorter is configured to achieve both crest factor reduction (CFR) and predistortion for linearization. One embodiment advantageously reduces processing requirements conventionally associated with CFR by considering only the in-band component, that is, the information bearing component, of the desired signal to be reproduced for those cases in which the mitigation of in-band error vector magnitude (EVM) is preferred over the reduction of spurious out-of-band emissions.

A transmitting apparatus 100 operates a high-frequency power amplifier 105 as a nonlinear amplifier in a first mode, and operates high-frequency power amplifier 105 as a linear amplifier in a second mode. When high-frequency power amplifier 105 is operated as a nonlinear amplifier, the input level of high-frequency power amplifier 105 is varied by a variable gain amplifier 107 in accordance with the average output power of a transmit signal. Transmitting apparatus 100 is also provided with a compensation table 121 for reducing error in high-frequency power amplifier 105 mode switching operations.