Adaptive digital linearization of a DRP based edge transmitter for cellular handsets

Waheed, K.; Ba, S.N.

doi:10.1109/mwscas.2007.4488676

Cited by 6 publications

(4 citation statements)

References 13 publications

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“…Therefore, previous works have aimed at calibrating/compensating these nonlinearities. For the AM path, [7] utilizes the on-chip receiver to conduct the adaptive digital linearization of the DPA, whereas in [8] this is achieved by coupling the RF signal to the reference clock of the ADPLL. For the PM path, [9] proposes a least-mean square based gain calibration technique of the DCO.…”

Section: Introductionmentioning

confidence: 99%

RF BIST for ADPLL-based polar transmitters with wide-band DCO gain calibration

Yin

2011

2011 12th International Symposium on Quality Electronic Design

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We propose a BIST scheme to provide online testing for all-digital PLL based polar transmitters. Multiple digital signatures are collected by adding a branch digital filter optimized to increase the sensitivities to nonidealities. The test signatures are processed using simple digital processing to provide an estimate for error vector magnitude (EVM), a key RF performance measure for the transmitter. Additionally, a digital self-calibration scheme is proposed to eliminate the EVM degradation due to large wide-band DCO gain mismatch. We show that a proper exploration of digital implementation style is instrumental for facilitating novel low-cost built-in test and calibration solutions for mixed-signal and RF applications.

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Section: Introductionmentioning

confidence: 99%

RF BIST for ADPLL-based polar transmitters with wide-band DCO gain calibration

Yin

2011

2011 12th International Symposium on Quality Electronic Design

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“…Instead of requiring dedicated hardware [2], the measurement setup is based on the existing receiver operating in half-duplex mode within the SoC, where the amplitude modulation/phase modulation (AM-PM) distortion Manuscript may be determined based on the use of the common oscillator for the receiver and the transmitter [3]. In this case, a signal coupled from the external power amplifier (PA) output to the receiver is mixed with the common local oscillator, resulting in downconversion of the transmitter's amplitude modulation (AM-AM) distortion and AM-PM response to baseband.…”

Section: Introductionmentioning

confidence: 99%

“…Since the proposed solution uses a linear PA, its distortions can be assumed memoryless, contrary to those of typical saturated PAs [6], and hence, the same predistortion design can be used. When the predistortion is to consider the distortions of the external PA as well, the coupling to the on-chip receiver can be achieved either through parasitic paths, or alternatively, an additional coupler can be added for the feedback [3], whereas in transmitters having an on-chip integrated PA, the output signal is available on-chip, such that the feedback is entirely internal. In summary, the distortions that are compensated for are measured at the point of interest in the transmitter and are digitized and stored in nonvolatile LUTs.…”

Section: Introductionmentioning

confidence: 99%

An Efficient Linearization Scheme for a Digital Polar EDGE Transmitter

Mehta

Zoicas

Eliezer

et al. 2010

IEEE Trans. Circuits Syst. II

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A new linearization scheme is proposed, which compensates for nonlinear distortions experienced in the amplitudemodulation path of a digital polar EDGE transmitter integrated in a 65-nm CMOS transceiver system-on-chip (SoC) based on the Digital RF Processor (DRP) technology. The measured amplitude and phase distortions are stored in lookup tables and used for predistortion without requiring inversion computations, thus achieving significant complexity reduction. Adaptive linear interpolation along with adaptive resolution enhancement provides the desired performance across power levels. With the presented scheme, the transmitter's measured performance significantly exceeds the EDGE specifications with an error vector magnitude (EVM) of typically 3% and a close-in modulated spectrum of −64 dB at a 400-kHz offset from the carrier frequency.

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“…The nonlinear gain and phase distortions of RF amplifiers are a strong function of the envelope fluctuations in an RF signal [2,3]. Consequently, most digital baseband predistorters are implemented as a function of the amplitude of the baseband input.…”

Section: Introductionmentioning

confidence: 99%

Efficient Lookup Table-Based Adaptive Baseband Predistortion Architecture for Memoryless Nonlinearity

Waheed

Zhou

2010

EURASIP J. Adv. Signal Process.

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Digital predistortion is an effective means to compensate for the nonlinear effects of a memoryless system. In case of a cellular transmitter, a digital baseband predistorter can mitigate the undesirable nonlinear effects along the signal chain, particularly the nonlinear impairments in the radiofrequency (RF) amplifiers. To be practically feasible, the implementation complexity of the predistorter must be minimized so that it becomes a cost-effective solution for the resource-limited wireless handset. This paper proposes optimizations that facilitate the design of a low-cost high-performance adaptive digital baseband predistorter for memoryless systems. A comparative performance analysis of the amplitude and power lookup table (LUT) indexing schemes is presented. An optimized low-complexity amplitude approximation and its hardware synthesis results are also studied. An efficient LUT predistorter training algorithm that combines the fast convergence speed of the normalized least mean squares (NLMSs) with a small hardware footprint is proposed. Results of fixed-point simulations based on the measured nonlinear characteristics of an RF amplifier are presented.

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Adaptive digital linearization of a DRP based edge transmitter for cellular handsets

Cited by 6 publications

References 13 publications

RF BIST for ADPLL-based polar transmitters with wide-band DCO gain calibration

RF BIST for ADPLL-based polar transmitters with wide-band DCO gain calibration

An Efficient Linearization Scheme for a Digital Polar EDGE Transmitter

Efficient Lookup Table-Based Adaptive Baseband Predistortion Architecture for Memoryless Nonlinearity

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