Curse of digital polar transmission: Precise delay alignment in amplitude and phase modulation paths

Waheed, K.; Staszewski, Robert Bogdan; Rezeq, S.

doi:10.1109/iscas.2008.4542124

Cited by 12 publications

(5 citation statements)

References 8 publications

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“…The results presented in [11] confirm this and also specifically demonstrate the sensitivity of the polar architecture to the timing alignment of the phase and amplitude paths, an alignment that becomes more demanding and problematic in wider bandwidth systems.…”

Section: ) Fully Digital Polar Transmittersupporting

confidence: 74%

All Digital-Quadrature-Modulator Based Wideband Wireless Transmitters

Parikh

Balsara

Eliezer

2009

IEEE Trans. Circuits Syst. I

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A novel architecture for a fully digital wideband wireless transmitter is presented. The proposed structure replaces high-dynamic-range analog circuits with high-speed digital circuits and offers a simple and flexible architecture, which requires less area, consumes less power, and delivers higher performance compared to those of the conventional modulators used for wideband systems. The design is based on a standard 65-nm CMOS process and is suitable for integration with a digital signal processor, memory, and logic implemented in such a process. The presented transmitter is based on a novel digital quadrature modulator (DQM), which achieves digital modulation in a Cartesian coordinate system. The novel architecture employs a single converter, referred to as the differential-like digital-to-RF converter (DDRC), as it is based on fully digitally combining the quadrature baseband signals. The DDRC, at the heart of the DQM, combines functionalities of a mixer, a digital-to-analog converter, and an RF filter into a single circuit. The total area for the digital blocks is 0 04 mm 2 , with a power consumption of roughly 5 mW. It is shown that the proposed transmitter meets the spectral mask, defined in the targeted IEEE 802.16e (WiMAX) standard, with a margin of 20 dB and achieves an error-vector-magnitude (EVM) performance of 36 dB with a margin of 6 dB.Index Terms-Differential-like digital-to-RF converter (DDRC), digital quadrature modulator (DQM), Digital RF Processor (DRP), digital transmitter, software-defined radio (SDR), system-on-chip (SoC), WiMAX.

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Section: ) Fully Digital Polar Transmittersupporting

confidence: 74%

All Digital-Quadrature-Modulator Based Wideband Wireless Transmitters

Parikh

Balsara

Eliezer

2009

IEEE Trans. Circuits Syst. I

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“…The level of the out-of-band spectrum is significantly below the mask given by the 3GPP for the used carrier frequency and bandwidth combination [1]. Consequently, there is much room for additional out-of-band degradations like nonideal components [20] or AM and PM mismatch [30]. However, the investigated effect scales with bandwidth to carrier frequency and poses a fundamental limitation that needs to be considered in scenarios where the ratio becomes smaller.…”

Section: B Compensation By Shifting the Edge Locationsmentioning

confidence: 99%

“…Several studies on the spectral degradation of a polar transmitter have already been published. Apart from investigations that focus on limitations like amplitude modulation (AM) and phase modulation (PM) mismatch [30], nonlinearities [20] or circuit noise, there are similar papers investigating principal limitations for polar-like systems. In [13] and [14] an outphasing transmitter is described and limitations and corrections are proposed regarding both phase components.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Spectral Degradation and Error Compensation in 5G NR Digital Polar Transmitters

Preissl

Preyler

Mayer

et al. 2020

IEEE Trans. Circuits Syst. I

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Cellular standards evolve to support increasingly higher bandwidths which results in strict in-and out-of-band requirements such as lower error vector magnitude (EVM) and/or adjacent channel leakage ratio (ACLR). Digital polar transmitters, which are showing the best performance in terms of power consumption, are challenged to fulfill these requirements. This work will show that even in case of ideal analog components and infinite digital resources, there are principle limitations in terms of out-of-band noise for digital polar transmitters. A typical polar modulation will be compared to a theoretical signal with continuous amplitude modulation. The analysis of the resulting error signal suggests a decomposition into two components which can be partially compensated in the amplitude and phase modulation paths. Based on that decomposition a compensation algorithm has been developed and evaluated with a 400 MHz 5G New Radio (NR) signal for Band n257 on Frequency Range 2 with carrier frequency of 26.5 GHz. The compensation results in an out-of-band noise reduction of 44 dB close to the carrier frequency. Furthermore, EVM improvements for NR signals are demonstrated.

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“…In the phase modulator, a delay mismatch between lowpass and high-pass path is caused by digital and analog blocks [12]. The digital delay mismatch is mainly due to different signal processing latencies in the two paths, as seen in Fig.…”

Section: A Delay Calibrationmentioning

confidence: 99%

A Highly Reconfigurable RF-DPLL Phase Modulator for Polar Transmitters in Cellular RFICs

Buckel¹,

Tertinek

Mayer

et al. 2018

IEEE Trans. Microwave Theory Techn.

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A multirate fractional-N RF digital phase-locked loop (DPLL) phase modulator implementation for polar transmitter supporting cellular communication standards up to 4G LTE-A is demonstrated. The RF-DPLL integrates LC-tank-based digitalcontrolled oscillator (DCO) cores with --noise shaping and fractional sample rate conversion to account for a broad range of frequency bands and spectral emission requirements. A twopoint modulation with different sampling rates and signal scaling is applied to optimize the system for operation in narrow-band and wide-band phase modulation. DCO digital predistortion and DCO gain estimation in combination with open-loop gain auto adjustment and delay calibration are implemented to achieve sufficiently low-in-band distortion. Measurement results of the RF-DPLL system as part of a polar transmitter implemented in 28-nm CMOS are shown, fulfilling 3GPP specifications for 4G, LTE-A uplink and legacy cellular communication standards like 3G, UMTS/HSPA+ and 2G, GSM/EDGE.

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Curse of digital polar transmission: Precise delay alignment in amplitude and phase modulation paths

Cited by 12 publications

References 8 publications

All Digital-Quadrature-Modulator Based Wideband Wireless Transmitters

All Digital-Quadrature-Modulator Based Wideband Wireless Transmitters

Analysis of Spectral Degradation and Error Compensation in 5G NR Digital Polar Transmitters

A Highly Reconfigurable RF-DPLL Phase Modulator for Polar Transmitters in Cellular RFICs

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