Quantization Noise Suppression for Envelope Pulse-Width Modulation (EPWM) Transmitters

Umali, Edwin M.; Yokozawa, Shinsuke; Yamao, Yasushi

doi:10.1109/vetecf.2010.5594208

Cited by 7 publications

(4 citation statements)

References 7 publications

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“…With tri-level encoding, the coding efficiency is improved compared with a single-bit case, and the sampling frequency is lowered to 522.24 MHz, which is worthy of notice among those of previous EPWM studies [2], [4]- [5]. The delay adjustment technique is also included to control the timing mismatch of the signal paths.…”

Section: Introductionmentioning

confidence: 96%

“…By adopting the 1-bit encoder, the EPWM transmitter can achieve high power efficiency with fully saturated operation of the power amplifiers (PAs), however, it cannot avoid excessive power loss and efficiency degradation, due to the encoder's low coding efficiency [5], [7], [9]. In addition, the sampling frequency (f s ) of the modulator should be the same as or higher than the RF carrier frequency (f c ), which makes the circuit implementation difficult [2], [4]- [5]. The non-ideal effects resulting from the higher f s can deteriorate the signal-to-noise ratio, causing nonlinearity concerns and power efficiency problems.…”

Section: Introductionmentioning

confidence: 99%

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A CMOS advanced class-S transmitter architecture based on tri-level envelope encoding

Cho

Lee

Jang

et al. 2014

2014 44th European Microwave Conference

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An advanced class-S transmitter architecture using a tri-level envelope encoding is presented. With tri-level encoding based on a delta-sigma modulator (DSM), a coding efficiency is improved compared to the two-level case, and sampling frequency is lowered to 522.24 MHz, which leads to an enhanced system efficiency. An analog/RF interface block is designed to control the propagation delay of the envelope signal. A wideband mixer and drive amplifier are also included to combine the modulated envelope with the phase signal and shift the spectrum to a 2.6-GHz center frequency. Measurement results from an implementation in a 130 nm CMOS process show that the DSM achieves a peak signal-to-noise and distortion ratio of 44.4 dB in a 20-MHz input bandwidth. Transmitter measurements on a 10-MHz long-term evolution signal show an error vector magnitude of 3.2% and an adjacent channel leakage ratio of 40.5 dB at 2.6 GHz.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

A CMOS advanced class-S transmitter architecture based on tri-level envelope encoding

Cho

Lee

Jang

et al. 2014

2014 44th European Microwave Conference

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“…A particular 1-bit encoder such as delta-sigma modulator (DSM) or pulsewidth modulation (PWM) transforms the varying envelope signal into square waves [8], [9]. Although the EPWM transmitter by adopting 1-bit encoder can achieve high power efficiency with the fully saturated operation of the power amplifiers, it cannot avoid excessive power loss and efficiency degradation due to the encoder's low coding efficiency.…”

Section: Introductionmentioning

confidence: 99%

20-MHz bandwidth continuous-time delta-sigma modulator for EPWM transmitter

Cho

Lee

Jang

et al. 2012

2012 International Symposium on Wireless Communication Systems (ISWCS)

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A 1.5-bit 20-MHz bandwidth continuous-time deltasigma modulator (CT-DSM), which is suitable for envelope pulsewidth modulation (EPWM) transmitters, is presented. To compensate the process-voltage-temperature variation, a resistor calibration method is proposed. The proposed calibration scheme improves a signal-to-quantization-noise-ratio (SQNR) by 18%. The switched capacitor digital-to-analog converter (DAC) and tri-level output DAC are adopted to improve non-ideal effects and implement multi-level encoding, respectively. Over 44 dB SQNR has been achieved for all corner simulation condition with an oversampling ratio of 13.056 and 20-MHz of bandwidth. The power consumption of the modulator is 11.6 mW from the 1.08 V supply. 1.74 % of error vector magnitude can be obtained for a 20 MHz LTE signal with a 9.7 dB peak-to-average power ratio.

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“…By converting input signal envelop to a Pulse-Width-Modulation (PWM) format, EPWM transmitter removes the envelop variation of the input RF signal so that it can protect the input signal against nonlinear distortion. On the other hand, quantization noise is generated during this process, and it can be suppressed by a bandpass filter (BPF) and an Amplitude Noise Compensation (ANC) techniques [7]- [8].…”

Section: Introductionmentioning

confidence: 99%

OFDM Signal Transmission by EPWM Transmitter in Nonlinear RoF Channel

Matsuura

Yokozawa

et al. 2012

2012 IEEE 75th Vehicular Technology Conference (VTC Spring)

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Radio-over-Fiber (RoF) technology enables low-loss distribution of RF signals over optical fiber, which contributes much for spreading broadband wireless access services into inbuilding areas and outdoor dead-spots. However, current broadband wireless access systems employ OFDM schemes and suffer from nonlinear distortion of the RoF channel due to nonlinearity inherent in Electrical to Optical (E/O) conversion. In this paper, a new RoF transmission scheme employing Envelop Pulse-Width Modulation (EPWM) transmitter has been proposed to efficiently suppress the impact of RoF channel nonlinearity on OFDM signals. This idea is executed in a typical RoF channel that uses a Mach-Zehnder modulator as its E/O convertor. It is proved by both simulation and experiment that the EPWM-RoF scheme can achieve linear transmission of OFDM signal via nonlinear RoF channel.

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Quantization Noise Suppression for Envelope Pulse-Width Modulation (EPWM) Transmitters

Cited by 7 publications

References 7 publications

A CMOS advanced class-S transmitter architecture based on tri-level envelope encoding

A CMOS advanced class-S transmitter architecture based on tri-level envelope encoding

20-MHz bandwidth continuous-time delta-sigma modulator for EPWM transmitter

OFDM Signal Transmission by EPWM Transmitter in Nonlinear RoF Channel

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