摘要:
An amplifier comprises a power amplifier for amplifying an unmodulated high-frequency input signal, a first branching device which is provided at an input terminal side of the power amplifier and extracts a signal, a second branching device which is provided at an output terminal side of the power amplifier and extracts a signal, a mixer for mixing a signal from the first branching device and a signal from the second branching device, a low-pass filter for removing a frequency band component of the input signal from an output signal of the mixer, a high-pass filter for removing a DC component from an output signal of the low-pass filter, and a wave detector for extracting a signal.
摘要:
An apparatus and a method select and use parameter values for an RF power amplifier linearizer to pre-distort the input signals of a power amplifier, so as to achieve a linear output response in the power amplifier. The apparatus and the method select from a number sets of parameter values, each set of parameter values corresponding to a different output power range of the power amplifier. The set of parameters include a coefficient vector tailored for the particular output power range for that set. The power amplifier input power is repeatedly measured and filtered at various time intervals. The input power measurements may be filtered by a fast attack/slow decay filter, which follows the peaks of the measurements under operation of the fast attack portion of the filter and provides a low variance during operation of the slow decay portion of the filter. The coefficient values for the predistortion linearization of the power amplifier is adapted dynamically, in response to changes in the input power level of the power amplifier. In one embodiment, hysteresis is used to reduce the rate at which the predistortion linearizer hops between two sets of the parameter values. Using the apparatus and the method, good ACLR across a wide range of power amplifier output power is achieved. Such characteristics are particularly advantageous in a system in which waveforms having fast power transients are present.
摘要:
The present invention relates to a method for detecting signal nonlinear distortion magnitude, used for extracting and detecting the nonlinear distortion output by a radio frequency power amplifier, characterized in respectively extracting input signal and output signal, and performing square after matching the amplitudes and frequencies of the input signal and output signal respectively, obtaining respective low frequency components of the squared input signal and output signal, therefore, the carrier component of the signals can be filtered, and the low frequency components can characterize the distorted signal feature as well as facilitate handling. The present invention performs square after matching the input signal and output signal, extracts the low frequency component, and then the relativity with the frequency and bandwidth of the signal is low, therefore, the difficulty in detecting the distortion can be reduced greatly. In addition, the square is equivalent to amplify the distortion, which is favorable to improve the detection sensitivity of output distortion.
摘要:
A power supply for providing a modulated output voltage to a load is disclosed. According to various embodiments, the power supply comprises a plurality of parallel-connected switch-mode power modules and a controller. The controller is connected to each of the power modules and is for controlling the duty cycles of the respective power modules such that the power modules have a common duty cycle in steady state, but in a phase-shifted or “interleaved” manner. In addition, the controller is for controlling the output voltage of the power converter by controlling the ratio of power modules in the forward state at a time to the total number of power modules. In this way, by providing a sufficiently large number of power modules, arbitrarily low output voltage amplitudes and intra-level oscillations can be achieved. Further, the rate of modulation of the output voltage can exceed the switching frequency (f=1/T, where T is the switching period) of the power modules. An rf power amplifier system including such a power supply is also disclosed.
摘要:
A power supply for providing a modulated output voltage to a load is disclosed. According to various embodiments, the power supply comprises a plurality of parallel-connected switch-mode power modules and a controller. The controller is connected to each of the power modules and is for controlling the duty cycles of the respective power modules such that the power modules have a common duty cycle in steady state, but in a phase-shifted or “interleaved” manner. In addition, the controller is for controlling the output voltage of the power converter by controlling the ratio of power modules in the forward state at a time to the total number of power modules. In this way, by providing a sufficiently large number of power modules, arbitrarily low output voltage amplitudes and intra-level oscillations can be achieved. Further, the rate of modulation of the output voltage can exceed the switching frequency (f=1/T, where T is the switching period) of the power modules. An rf power amplifier system including such a power supply is also disclosed.
摘要:
A controller for an RF amplifier, in particular for a RF amplifier of an MR tomography apparatus, has an IQ control element for adjusting the magnitude and phase an RF signal that is be fed to the RF amplifier. The IQ control element has a signal splitter that splits the RF signal into two partial signals having a 90° phase offset in an I path and a Q path, each having a multiplier for multiplying the partial signal by an I factor in the I path and a Q factor in the Q path. A summing unit recombines the partial signals. A detector determines the actual phase difference and actual amplification between the RF signal fed to the IQ control element and the RF signal amplified by the RF amplifier. An IQ controller determines the I factor and the Q factor from the actual difference and a desired phase difference and the actual amplifier and a desired amplification. The IQ controller has an operating point at which the I factor and the Q factor are the same magnitude if the actual and desired phase differences and the actual and desired amplifications are the same.
摘要:
A bias controller sets the quiescent current of a power amplifier to a desired value by dynamically adjusting the power amplifier bias voltage. Using closed-loop control, the bias controller sets the bias voltage to whatever value is needed despite circuit component variations and temperature effects. Operation of the bias controller complements dynamic bias voltage adjustment in advance of transmit operations, such as in advance of a transmit burst. In a first state, where the power amplifier is in a quiescent condition, the bias controller adjusts bias voltage to set the desired quiescent current by detecting the supply current into the power amplifier. The bias controller then transitions to a second state, where it maintains the adjusted bias voltage irrespective of amplifier supply current. Despite its ability to sense supply current into the power amplifier, the bias controller's configurations avoid dissipative current sensing during normal operation of the power amplifier.
摘要:
Aspects of this disclosure relate to protecting a circuit, such as an amplifier, from transient overdrive events and/or average overdrive events. In one embodiment, an indication of average power, such as root mean squared (RMS) power of a radio frequency (RF) signal, can be compared to a first threshold and an indication of a peak RF power can be compared to a second threshold. When the indication of average power exceeds the first threshold, an average overdrive event can be detected. When the indication of peak power exceeds the second threshold, a peak overdrive event can be detected. If either a transient overdrive event or an average overdrive event is detected, a circuit, such as an amplifier, can be protected.
摘要:
Aspects of this disclosure relate to protecting a circuit, such as an amplifier, from transient overdrive events and/or average overdrive events. In one embodiment, an indication of average power, such as root mean squared (RMS) power of a radio frequency (RF) signal, can be compared to a first threshold and an indication of a peak RF power can be compared to a second threshold. When the indication of average power exceeds the first threshold, an average overdrive event can be detected. When the indication of peak power exceeds the second threshold, a peak overdrive event can be detected. If either a transient overdrive event or an average overdrive event is detected, a circuit, such as an amplifier, can be protected.
摘要:
Fuzzy logic is utilized to control an RF amplifier and associated tuner for continuous self-optimization and automatic load matching to at least double the battery life of a battery-powered transmitter.