In this article the effects of non-linearities and other impairments in a direct up-conversion tr... more In this article the effects of non-linearities and other impairments in a direct up-conversion transmitter is investigated. A method to find the different parameters of the non-linearities and of the impairments without doing internal measurements is developed and simulated and its robustness against divergence from ideal conditions and against noise is investigated. By using simple non-linear models for the nonlinearities at baseband and for the power amplifier, PA, a total mathematical model of the transmitter is obtained. From the model it can be seen that both the amplitude and the phase distortion of the transmitter are dependent on both the phase and the envelope of the input signal. The parameters of this model is then identified by studying the amplitude and phase distortion at the output. The impact of noise and of modelling errors are studied by simulations and it is found that the method is robust against modelling errors and that the sensitivity to noise is strongly dependent on the strength of the non-linearity. If the identified parameters are used to distort a two-tone input signal, the error in third order intermodulation products are less than 0.5 dB for both the baseband alone, for the PA alone and for the system as a whole, except for the case of low signal-to-noise ratio.
In this paper a power amplifier is measured and characterized by the use of the generalized Zhu-F... more In this paper a power amplifier is measured and characterized by the use of the generalized Zhu-Frank sampling theorem. A specially designed test-bed has been used allowing the bandwidth of the stimuli signal to be 100 MHz in the characterization process.
In this paper the software and hardware structure of a virtual instrument measurement system is d... more In this paper the software and hardware structure of a virtual instrument measurement system is discussed. The focus is on flexibility, modularity, generality and hardware independence. A software architecture that meets these requirements is proposed and discussed in some detail. The proposed software architecture has a layered structure that makes it suitable for implementation of versatile measurement systems. The measurement functionality is encapsulated in its own, hardware independent layer and communicates with its environment, e.g. physical hardware, through intermediary software components. Finally a measurement system for characterization of power amplifiers that is designed following the proposed software architecture, with software driven measurements, is implemented.
A Doherty amplifier was investigated using behavioral amplifier modeling techniques. A measuremen... more A Doherty amplifier was investigated using behavioral amplifier modeling techniques. A measurement system for simultaneous wide bandwidth (>100 MHz) and large dynamic range (-70 dBc ACLR) sampled measurements that are needed for the behavioral modeling is presented. Both the measurement system and the performance of the Doherty amplifier are described. The findings are that the well known and widely used
In this paper, the functionality of a vector network analyzer VNA is implemented using the concep... more In this paper, the functionality of a vector network analyzer VNA is implemented using the concept of software defined measurements (SDM) [1], called SDM-VNA. A general measurement set-up based on a vector signal generator (VSG) and a vector signal analyzer (VSA) is used. The set-up allows complete linear characterization using only one receiver. A calibration procedure to remove the systematic
This paper presents a novel test setup, based on a vector signal generator (VSG) and a vector sig... more This paper presents a novel test setup, based on a vector signal generator (VSG) and a vector signal analyzer (VSA), capable of nonlinear characterization of communications devices such as RF power amplifiers. Envelope time-domain waveform extraction and correction is applied to the DUT reference plane, preserving vector correction even in modulated environments where ingoing and outgoing signals from the ports of the DUT can be distinguished. This tool is valuable in the analysis of nonlinear devices, the generation of behavioral models and the study of memory effects..
IEEE Transactions on Instrumentation and Measurement, 2000
A decrease in life cycle cost is a key issue for testing mobile communication systems. The rapid ... more A decrease in life cycle cost is a key issue for testing mobile communication systems. The rapid development and edge technology requires high-performance instruments and state-of-the-art measurement technology. New investments are expensive, but even older generation instruments are capable of extending their bandwidth and dynamic range to meet even the latest Third-Generation Partnership Project (3GPP) cellular measurement requirements by the addition of external hardware using a synthetic instrument approach. The novelty of this paper is the high performance on the most crucial parameters, i.e., the dynamic range and bandwidth achieved by only replacing some parts of the legacy instrument. Moreover, the demonstrated direct IF synthesis has a high degree of novelty at wide modulation bandwidths. It is desired to use virtual/synthetic instruments and make the signal processing in the software independent of the hardware, i.e., software-defined measurements (SDMs). In this paper, a state-of-the-art experimental setup for signal generation and signal analysis is demonstrated. A direct IF synthesis is used to generate a wideband code-division multiple-access (WCDMA) carrier with more than 72-dB adjacent carrier leakage ratio (ACLR) up to 12 parallel carriers with more than 68-dBc ACLR over a total bandwidth of 100 MHz. The signal analysis capabilities (e.g., ACLR performance) for a WCDMA carrier is better than −70 dBc and for a continuous wave better than −85 dBc over a bandwidth of 42.5 MHz. The critical RF downconverter in the setup is carefully designed not to degrade the dynamic range performance.
This paper presents a novel test setup, based on a vector signal generator (VSG) and a vector sig... more This paper presents a novel test setup, based on a vector signal generator (VSG) and a vector signal analyzer (VSA), capable of nonlinear characterization of communications devices such as RF power amplifiers.
ABSTRACT This paper describes, and discusses in some detail, a measurement system for dynamic cha... more ABSTRACT This paper describes, and discusses in some detail, a measurement system for dynamic characterization of power amplifiers. The system uses data that are generated and collected at baseband to accurately calculate AM/AM and AM/PM distortion as well as memory effects in the amplifiers. The limitations of the system in terms of dynamic range and bandwidth are discussed as well as techniques to overcome them. The system may serve as a tool both for designers of power amplifiers as well for development of amplifier models and systems for predistortion.
... the dynamic range as well as the bandwidth since it allows the use of a digital IF receiver i... more ... the dynamic range as well as the bandwidth since it allows the use of a digital IF receiver in the signal analyser without loss of bandwidth. IV. RESULTS Measurements were done on a class A GaAs FET amplifier using an eight-tone signal with a peak-to-average power ratio of ...
Proceedings of the 20th IEEE Instrumentation Technology Conference (Cat. No.03CH37412), 2003
... the dynamic range as well as the bandwidth since it allows the use of a digital IF receiver i... more ... the dynamic range as well as the bandwidth since it allows the use of a digital IF receiver in the signal analyser without loss of bandwidth. IV. RESULTS Measurements were done on a class A GaAs FET amplifier using an eight-tone signal with a peak-to-average power ratio of ...
In this article the effects of non-linearities and other impairments in a direct up-conversion tr... more In this article the effects of non-linearities and other impairments in a direct up-conversion transmitter is investigated. By using simple non-linear models for the non-linearities at baseband and for the power amplifier, a total mathematical model of the transmitter is obtained. From the model it can be seen that both the amplitude and the phase distortion of the transmitter are dependent on both the phase and the envelope of the input signal. The parameters of the non-linear baseband and RF distortion of this model are then identified separately by studying the amplitude and phase distortion of the output signal. The method is verified by measurements and it is found that the identified parameters can be used to accurately re-generate the measured output signal in the sense that all main distortion products, i.e. larger than ¿60 dBc, of the re-generated signal will be within a dB of the distortion products of the measured signal.
In this paper it is shown that for the purpose of nonlinear power amplifier behavioural modelling... more In this paper it is shown that for the purpose of nonlinear power amplifier behavioural modelling, the sampling rate can be set to the Nyquist rate of the input signal, rather than to the Nyquist rate of the output signal by making use of Zhu's generalized sampling theorem. This claim is supported by measurements on a basestation power amplifier. The findings are that the model error obtained when the output signal is sampled at the Nyquist rate of the input signal is approximately 1.5 dB higher than when the sampling rate is set to the Nyquist rate of the output signal. However, if a sampling rate of twice the Nyquist rate of the input signal is used, which is still typically, much lower than the Nyquist rate of the output signal, the degradation is only 0.2 dB. These are important findings that will substantially ease the requirements on ADCs used in measurement set- ups used for amplifier modelling.
In this article the effects of non-linearities and other impairments in a direct up-conversion tr... more In this article the effects of non-linearities and other impairments in a direct up-conversion transmitter is investigated. A method to find the different parameters of the non-linearities and of the impairments without doing internal measurements is developed and simulated and its robustness against divergence from ideal conditions and against noise is investigated. By using simple non-linear models for the nonlinearities at baseband and for the power amplifier, PA, a total mathematical model of the transmitter is obtained. From the model it can be seen that both the amplitude and the phase distortion of the transmitter are dependent on both the phase and the envelope of the input signal. The parameters of this model is then identified by studying the amplitude and phase distortion at the output. The impact of noise and of modelling errors are studied by simulations and it is found that the method is robust against modelling errors and that the sensitivity to noise is strongly dependent on the strength of the non-linearity. If the identified parameters are used to distort a two-tone input signal, the error in third order intermodulation products are less than 0.5 dB for both the baseband alone, for the PA alone and for the system as a whole, except for the case of low signal-to-noise ratio.
In this paper a power amplifier is measured and characterized by the use of the generalized Zhu-F... more In this paper a power amplifier is measured and characterized by the use of the generalized Zhu-Frank sampling theorem. A specially designed test-bed has been used allowing the bandwidth of the stimuli signal to be 100 MHz in the characterization process.
In this paper the software and hardware structure of a virtual instrument measurement system is d... more In this paper the software and hardware structure of a virtual instrument measurement system is discussed. The focus is on flexibility, modularity, generality and hardware independence. A software architecture that meets these requirements is proposed and discussed in some detail. The proposed software architecture has a layered structure that makes it suitable for implementation of versatile measurement systems. The measurement functionality is encapsulated in its own, hardware independent layer and communicates with its environment, e.g. physical hardware, through intermediary software components. Finally a measurement system for characterization of power amplifiers that is designed following the proposed software architecture, with software driven measurements, is implemented.
A Doherty amplifier was investigated using behavioral amplifier modeling techniques. A measuremen... more A Doherty amplifier was investigated using behavioral amplifier modeling techniques. A measurement system for simultaneous wide bandwidth (>100 MHz) and large dynamic range (-70 dBc ACLR) sampled measurements that are needed for the behavioral modeling is presented. Both the measurement system and the performance of the Doherty amplifier are described. The findings are that the well known and widely used
In this paper, the functionality of a vector network analyzer VNA is implemented using the concep... more In this paper, the functionality of a vector network analyzer VNA is implemented using the concept of software defined measurements (SDM) [1], called SDM-VNA. A general measurement set-up based on a vector signal generator (VSG) and a vector signal analyzer (VSA) is used. The set-up allows complete linear characterization using only one receiver. A calibration procedure to remove the systematic
This paper presents a novel test setup, based on a vector signal generator (VSG) and a vector sig... more This paper presents a novel test setup, based on a vector signal generator (VSG) and a vector signal analyzer (VSA), capable of nonlinear characterization of communications devices such as RF power amplifiers. Envelope time-domain waveform extraction and correction is applied to the DUT reference plane, preserving vector correction even in modulated environments where ingoing and outgoing signals from the ports of the DUT can be distinguished. This tool is valuable in the analysis of nonlinear devices, the generation of behavioral models and the study of memory effects..
IEEE Transactions on Instrumentation and Measurement, 2000
A decrease in life cycle cost is a key issue for testing mobile communication systems. The rapid ... more A decrease in life cycle cost is a key issue for testing mobile communication systems. The rapid development and edge technology requires high-performance instruments and state-of-the-art measurement technology. New investments are expensive, but even older generation instruments are capable of extending their bandwidth and dynamic range to meet even the latest Third-Generation Partnership Project (3GPP) cellular measurement requirements by the addition of external hardware using a synthetic instrument approach. The novelty of this paper is the high performance on the most crucial parameters, i.e., the dynamic range and bandwidth achieved by only replacing some parts of the legacy instrument. Moreover, the demonstrated direct IF synthesis has a high degree of novelty at wide modulation bandwidths. It is desired to use virtual/synthetic instruments and make the signal processing in the software independent of the hardware, i.e., software-defined measurements (SDMs). In this paper, a state-of-the-art experimental setup for signal generation and signal analysis is demonstrated. A direct IF synthesis is used to generate a wideband code-division multiple-access (WCDMA) carrier with more than 72-dB adjacent carrier leakage ratio (ACLR) up to 12 parallel carriers with more than 68-dBc ACLR over a total bandwidth of 100 MHz. The signal analysis capabilities (e.g., ACLR performance) for a WCDMA carrier is better than −70 dBc and for a continuous wave better than −85 dBc over a bandwidth of 42.5 MHz. The critical RF downconverter in the setup is carefully designed not to degrade the dynamic range performance.
This paper presents a novel test setup, based on a vector signal generator (VSG) and a vector sig... more This paper presents a novel test setup, based on a vector signal generator (VSG) and a vector signal analyzer (VSA), capable of nonlinear characterization of communications devices such as RF power amplifiers.
ABSTRACT This paper describes, and discusses in some detail, a measurement system for dynamic cha... more ABSTRACT This paper describes, and discusses in some detail, a measurement system for dynamic characterization of power amplifiers. The system uses data that are generated and collected at baseband to accurately calculate AM/AM and AM/PM distortion as well as memory effects in the amplifiers. The limitations of the system in terms of dynamic range and bandwidth are discussed as well as techniques to overcome them. The system may serve as a tool both for designers of power amplifiers as well for development of amplifier models and systems for predistortion.
... the dynamic range as well as the bandwidth since it allows the use of a digital IF receiver i... more ... the dynamic range as well as the bandwidth since it allows the use of a digital IF receiver in the signal analyser without loss of bandwidth. IV. RESULTS Measurements were done on a class A GaAs FET amplifier using an eight-tone signal with a peak-to-average power ratio of ...
Proceedings of the 20th IEEE Instrumentation Technology Conference (Cat. No.03CH37412), 2003
... the dynamic range as well as the bandwidth since it allows the use of a digital IF receiver i... more ... the dynamic range as well as the bandwidth since it allows the use of a digital IF receiver in the signal analyser without loss of bandwidth. IV. RESULTS Measurements were done on a class A GaAs FET amplifier using an eight-tone signal with a peak-to-average power ratio of ...
In this article the effects of non-linearities and other impairments in a direct up-conversion tr... more In this article the effects of non-linearities and other impairments in a direct up-conversion transmitter is investigated. By using simple non-linear models for the non-linearities at baseband and for the power amplifier, a total mathematical model of the transmitter is obtained. From the model it can be seen that both the amplitude and the phase distortion of the transmitter are dependent on both the phase and the envelope of the input signal. The parameters of the non-linear baseband and RF distortion of this model are then identified separately by studying the amplitude and phase distortion of the output signal. The method is verified by measurements and it is found that the identified parameters can be used to accurately re-generate the measured output signal in the sense that all main distortion products, i.e. larger than ¿60 dBc, of the re-generated signal will be within a dB of the distortion products of the measured signal.
In this paper it is shown that for the purpose of nonlinear power amplifier behavioural modelling... more In this paper it is shown that for the purpose of nonlinear power amplifier behavioural modelling, the sampling rate can be set to the Nyquist rate of the input signal, rather than to the Nyquist rate of the output signal by making use of Zhu's generalized sampling theorem. This claim is supported by measurements on a basestation power amplifier. The findings are that the model error obtained when the output signal is sampled at the Nyquist rate of the input signal is approximately 1.5 dB higher than when the sampling rate is set to the Nyquist rate of the output signal. However, if a sampling rate of twice the Nyquist rate of the input signal is used, which is still typically, much lower than the Nyquist rate of the output signal, the degradation is only 0.2 dB. These are important findings that will substantially ease the requirements on ADCs used in measurement set- ups used for amplifier modelling.
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