Error Vector Magnitude Performance Research Articles

30–66 GHz millimetre wave phase shift keying modulator: performance and analysis

An octave bandwidth millimetre wave gallium arsenide (GaAs) MMIC modulator is demonstrated, wherein a novel method for directly producing QPSK/OQPSK/BPSK modulation directly from baseband IQ signals is presented. A key feature of the architecture is the absence of mixers. Expressions detailing the overall modulator error vector magnitude (EVM) performance with regard to its constituent components are derived. The dc power consumption of the circuit is less than 50 mW, and its 1 dB compression point is above 7 dBm. Frequency operation is between 30 and 66 GHz, over which QPSK EVM is below 15%, BPSK EVM <3% and data rates of greater than 500 MB/s are possible.

EVM simulation and analysis in digital transmitter

The error vector magnitude (EVM) is extensively applied as a metric for digital transmitter signal quality compliance in modern communication systems. This article is focused on the effects of local oscillator (LO) phase noise and nonlinear distortion of power amplifier on EVM. This article contributes to below aspects. First, the relationships between EVM and two effects, LO phase noise and nonlinear distortion of power amplifier, are derived and expressed. Second, to simplify the expression, the third-order intermodulation distortion (IMD3) is used to calculate the EVM. Then, an expression for the EVM is derived based on the digital transmitter model that considers local oscillator phase noise and nonlinear distortion of power amplifier. Finally, the math formula of bit error rate (BER) versus EVM is given which can be easier and more useful to predict BER, according to analysis of the relationship between EVM and signal to noise rate (SNR), inspired by the works of Rishad, Md. Shahriar and AHM, 2006. Simulations are carried out to display the performance of EVM based on these relationships.

Improved Radio-Over-Fiber Transponder With Multistage Automatic Gain Control

In this paper, improved transponders with multistage automatic gain control (AGC) for radio-over-fiber-based distributed antenna systems are presented. Error vector magnitude performance measurements for both uplink and downlink paths are carried out to verify the feasibility of applying this system for IEEE 802.11g signal transmission. The developed conventional radio-over-fiber system shows its capability of supporting the wireless local area network signal transmission for an input dynamic range of approximately 14 dB. The improved radio-over-fiber systems with a single- and two-stage AGC are also demonstrated to have a better input dynamic range of 27 dB and more than 37 dB, respectively. The error vector magnitude for the case with a two-stage AGC is much better than that with a single-stage AGC.

2.4 GHz WLAN InGaP/GaAs Power Amplifier with Temperature Compensation Technique

This letter presents a high performance 2.4 GHz two-stage power amplifier (PA) operating in the temperature range from −30…C to +85oC for IEEE 802.11g, wireless local area network application. It is implemented in InGaP/GaAs hetero-junction bipolar transistor technology and has a bias circuit employing a temperature compensation technique for error vector magnitude (EVM) performance. The technique uses a resistor made with a base layer of HBT. The design improves EVM performance in cold temperatures by increasing current. The implemented PA has a dynamic EVM of less than 4%, a gain of over 26 dB, and a current less than 130 mA below the output power of 19 dBm across the temperature range from −30oC to +85oC.

Low-Cost Multistandard Radio-Over-Fiber Downlinks Based on CMOS-Compatible Si Avalanche Photodetectors

We demonstrate a radio-over-fiber downlink based on a silicon avalanche photodetector (APD) fabricated with 0.18-mum standard complementary metal-oxide-semiconductor (CMOS) technology. An 850-nm vertical-cavity surface-emitting laser is used to deliver multistandard services including 2.1-GHz wideband code-division multiple access and 2.4-GHz IEEE 802.11g wireless local area network signals over 300-m multimode fiber. These signals are successfully detected by a CMOS-compatible APD (CMOS-APD) and then transmitted to a mobile terminal via wireless link. The error vector magnitude performance of each type of signal with the coexisting interferer is investigated.

Full-Duplex Radio-Over-Fiber System Using Phase-Modulated Downlink and Intensity-Modulated Uplink

We propose and demonstrate a full-duplex radio-over-fiber system employing a phase-modulated downlink and an intensity-modulated uplink over a single optical carrier. Each downlink and uplink is encoded with 200-Mb/s 16-quadrature amplitude modulation and a 100-Mb/s quadrature phase-shift keying signal carried in the 6-GHz band, respectively. The demonstration results show that the constraints on modulation index of the downlink signal as well as power budget of uplink signal can be relaxed thanks to the constant intensity of the phase-modulated downlink signal. The results also show the good error vector magnitude performance in both downlink and uplink signals after transmission over a 25-km fiber link. The effect of phase modulation to intensity modulation conversion of the downlink signal is also measured and evaluated for the scalability of the proposed technique.

Multilevel Modulated Signal Transmission Over Serial Single-Mode and Multimode Fiber Links Using Vertical-Cavity Surface-Emitting Lasers for Millimeter-Wave Wireless Communications

Quadrature phase-shift keying, 16 quadrature amplitude modulation (QAM), and 64-QAM data transmission - Worldwide Interoperability for Microwave Access modulation schemes - at 6 and 20 MS/s is demonstrated for a link that emulates a cost-effective 1.55 mum vertical-cavity surface-emitting laser based radio over fiber millimeter-wave indoor picocellular system. The system consists of a concatenation of 20-km single-mode fiber and 300-m multimode fiber links between a central office and remote antenna unit and employs remote 30-GHz local oscillator delivery. Successful transmission over both optical and wireless paths is achieved with good error vector magnitude performance recorded for both uplink and downlink. The performance is compared to other demonstrations of multilevel signal transmission in millimeter-wave over fiber systems.

EVM estimation by analyzing transmitter imperfections mathematically and graphically

This letter analyzes the effects of transmitter imperfections, including carrier leakage, unwanted sideband, nonlinearity, local oscillator (LO) phase noise and frequency error, on error vector magnitude (EVM) performance. Predictor equations of transmitter EVM are given for radio designers to estimate the level of EVM or set appropriate design specifications to obtain desired EVM performance. These predictor equations are validated by measurement results of other reported works.

On quantifying the benefits of SSPA linearization in UWC-136 systems

A novel comparative analysis of the benefits brought by different degrees of linearization to offset the modulation fidelity (MF) and spectrum regrowth impairments caused by solid-state power amplifier (SSPA) nonlinearity, as measured by error vector magnitude (EVM) and adjacent channel power ratio (ACPR) performance for TIA/EIA Universal Wireless Communication standard UWC-136 signals, are quantified. New results are presented showing the benefits of even modest levels of linearization but also that such benefits may be easily eroded at a receiver by the adjacent channel interference (ACI) in certain circumstances. An equation expressing the incremental MF deterioration experienced by a wanted channel (WC) signal, at its receiver, due to ACI arising from signals in the immediate upper and lower frequency channels, and as a function of adjacent channel (AC) to WC power differential, where signals are subject to different degrees of linearization, is presented. Typical SSPA characteristic values for the equation constants in the cases of one and two immediate AC signals are derived from simulation results. Interesting new results and conclusions relevant to the drafting of harmonious ACPR-EVM specifications and on the advisability of the inclusion of linearization schemes in transmitters, in the context of the UWC-136 system, are presented.

Improved Digital-IF Transmitter Architecture for Highly Integrated W-CDMA Mobile Terminals

An improved digital intermediate frequency (IF) transmitter architecture for wide-band code-division multiple-access (W-CDMA) mobile terminals is proposed. Based on the heterodyne design but without requiring any off-chip IF filter, the transmitter enjoys the advantages of a homodyne architecture (such as circuit simplicity, low power consumption, and a high level of integration) while avoiding the performance problems associated with direct upconversion. By implementing the quadrature modulation in the digital domain and requiring only a single path of analog baseband circuits, inherently perfect I/Q matching and good error vector magnitude (EVM) performance can be achieved. The IF is chosen to be a quarter of the clock rate for a very simple and low-power digital modulator design. The difficulties of on-chip IF filtering were greatly alleviated by 1) performing a careful frequency planning and 2) employing a special-purpose digital-to-analog converter to produce high-order sin(x)/x rolloff. System-level simulation demonstrates that spurious-emission requirements are met with virtually no dedicated reconstruction filter circuits. This architecture takes full advantage of complimentary metal-oxide-semiconductor technology scaling by employing digital processing to ease analog complexities.

Performance of EVM and PCDE quality metrics in WCDMA downlink

In a WCDMA system, the downlink signal the base station transmits is designed to fulfil the specifications set in the 3GPP standard. Here, the performance of the error vector magnitude (EVM) and peak code domain error (PCDE) quality metrics is impugned. It is shown that the limits of EVM and PCDE do not guarantee that the user will experience an adequate signal-to-noise ratio.

EVM and BER Simulation of an NADC-TDMA Radiophone Influenced by theOperator's Body in Urban Mobile Environments

This paper presents the performance evaluation of a portable digital radiophone influenced by the operator's body in urban mobile environments, based on the EVM (error vector magnitude) and BER (bit error rate) simulation. The type of digital modulation follows to the NADC-TDMA standard. A new probability density function (pdf) is proposed to describe the statistic of the EVM in an AWGN channel under frequency non-selective slowly fading situation. The simulation combines the modified Doppler power spectrum (MDPS) method and a gray coding (π/4-DQPSK modulation with square-root raised cosine (SRRC) shaping filter. The performance evaluation based on BER uses an ideal matched-filter-based receiver. The results show that the closer of the distance between the radiophone antenna and the operator's head, the poorer of the EVM and BER performance.

Adjacent channel power and error-vector magnitude performance of reduced complexity CALLUM systems

The combined analogue locked-loop universal modulator (CALLUM) is a power efficient linear RF transmitter based on the LINC principle (linear amplification with nonlinear components). The system provides both upconversion and amplification of a baseband input signal, within a closed-loop control scheme. The variant known as CALLUM1 is optimal, but difficult to implement practically. Simplifications to this system can be made so that the processing requirement is reduced. The simulated performance of these systems is compared to that of CALLUM1, in terms of adjacent channel power (ACP) and error-vector magnitude (EVMrms), in response to a TETRA (terrestrial trunked radio) baseband modulation signal. The existing CALLUM systems and the simplified versions proposed in the paper meet the TETRA ACP specification of –60 dBc if enough stable loop gain can be provided.