Analytical BER Performance of M-QAM-OFDM Systems in the Presence of IQ Imbalance

Zareian, Hassan; Vakili, Vahid Tabataba

doi:10.1109/wocn.2007.4284141

Cited by 16 publications

(21 citation statements)

References 2 publications

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“…1, a 28 GHz QVCO [7][8][9] is used to generate the 84 GHz TX carrier in two steps [10]. A direct conversion architecture, with a QVCO operating at the 84 GHz carrier frequency, is not preferred due to stringent requirements on I/Q phase error for higher order QAM modulation [17][18][19][20]. The effect of device mismatch is worse for a higher frequency QVCO and I/Q mixer.…”

Section: Transmitter Architecturementioning

confidence: 99%

“…Any modeling error can therefore result in significant loss in signal transfer. For the presented transmitter, intended for higher order QAM modulation, also the matching between different inductive elements is important, since any imbalance can result in impairments of the transmitted signal [17][18][19][20]. Even small imbalances in capacitive parasitics, in the range of a few femtofarads, can result in I/Q phase errors that cause significant degradation in the BER [7,8] of the radio link.…”

Section: Electromagnetic Simulationmentioning

confidence: 99%

“…For a high data-rate wireless link using QAM modulation, the transmitter linearity, LO phase noise and I/Q phase imbalance are highly important [16][17][18][19][20], since they impact the achievable BER. During the design of a MM-wave transmitter it is therefore of great value if the expected BER due to transmitter imperfections can be estimated.…”

Section: Error Vector Magnitude (Evm) In Transmittersmentioning

confidence: 99%

“…The definition of the Error Vector Magnitude (EVM) is illustrated in Fig. 18(b) [17][18][19][20], showing the difference between an ideal transmitted constellation point and the actual transmitted point. The rms error vector magnitude, EVM rms , is defined in (4) [21], as the normalized root mean square value of the errors of a large number (N) of constellation points.…”

Section: Error Vector Magnitude (Evm) In Transmittersmentioning

confidence: 99%

“…In E-band systems of today, to support spectral efficient transmission with high data rates, M-ary QAM is used. For low bit-error (BER), data links using QAM modulation put more stringent requirements on transmitter nonidealities, resulting in tight error-vectormagnitude (EVM) specifications [17][18][19][20][21][22]. In this paper, the effects on simulated EVM, for a 2 GHz 16 QAM signal, of local oscillator (LO) phase noise, I/Q imbalance, and PA compression are therefore investigated.…”

Section: Introductionmentioning

confidence: 99%

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System simulations of a 1.5 V SiGe 81–86 GHz E-band transmitter

Tired

Sandrup

Nejdel

et al. 2016

Analog Integr Circ Sig Process

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This paper presents simulation results for a sliding-IF SiGe E-band transmitter circuit for the 81-86 GHz E-band. The circuit was designed in a SiGe process with f T = 200 GHz and uses a supply of 1.5 V. The low supply voltage eliminates the need for a dedicated transmitter voltage regulator. The carrier generation is based on a 28 GHz quadrature voltage oscillator (QVCO). Upconversion to 84 GHz is performed by first mixing with the QVCO signals, converting the signal from baseband to 28 GHz, and then mixing it with the 56 GHz QVCO second harmonic, present at the emitter nodes of the QVCO core devices. The second mixer is connected to a threestage power amplifier utilizing capacitive cross-coupling to increase the gain, providing a saturated output power of ?14 dBm with a 1 dB output compression point of ?11 dBm. E-band radio links using higher order modulation, e.g. 64 QAM, are sensitive to I/Q phase errors. The presented design is based on a 28 GHz QVCO, the lower frequency reducing the phase error due to mismatch in active and passive devices. The I/Q mismatch can be further reduced by adjusting varactors connected to each QVCO output. The analog performance of the transmitter is based on ADS Momentum models of all inductors and transformers, and layout parasitic extracted views of the active parts. For the simulations with a 16 QAM modulated baseband input signal, however, the Momentum models were replaced with lumped equivalent models to ease simulator convergence. Constellation diagrams and error vector magnitude (EVM) were calculated in MATLAB using data from transient simulations. The EVM dependency on QVCO phase noise, I/Q imbalance and PA compression has been analyzed. For an average output power of 7.5 dBm, the design achieves 7.2% EVM for a 16 QAM signal with 1 GHz bandwidth. The current consumption of the transmitter, including the PA, equals 131 mA from a 1.5 V supply.

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Section: Transmitter Architecturementioning

confidence: 99%

Section: Electromagnetic Simulationmentioning

confidence: 99%

Section: Error Vector Magnitude (Evm) In Transmittersmentioning

confidence: 99%

Section: Error Vector Magnitude (Evm) In Transmittersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

System simulations of a 1.5 V SiGe 81–86 GHz E-band transmitter

Tired

Sandrup

Nejdel

et al. 2016

Analog Integr Circ Sig Process

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A 28 GHz SiGe PLL for an 81–86 GHz E-band beam steering transmitter and an I/Q phase imbalance detection and compensation circuit

Tired

Sjöland

Sandrup

et al. 2015

Analog Integr Circ Sig Process

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This paper presents two circuits, a complete 1.5 V 28 GHz SiGe beam steering PLL and a standalone 28 GHz QVCO with I/Q phase imbalance detection and compensation. The circuits were designed in a SiGe process with f T = 200 GHz. The PLL is intended to be used for beam steering in an 81-86 GHz E-band transmitter. Phase control is implemented by DC current injection at the output of a Gilbert architecture phase detector showing a simulated phase control sensitivity of 1.2°/lA over a range close to 180°. The simulations use layout parasitics for the QVCO, frequency divider, and phase detector, and an electromagnetic model for the QVCO inductors. The divider is implemented with four cascaded divide-by-two current-mode-logic blocks for a reference frequency of 1.75 GHz. For closed loop simulations of PLL noise and stability, the QVCO is represented with a behavior model with added phase noise. This simulation technique enabled faster simulation time of the PLL. The PLL in band phase noise at 1 MHz offset equals -115 dBc/Hz. Excluding output buffers, the entire PLL consumes 52 mW plus a minimum 7 mW from a variable high voltage supply required to extend the PLL locking range. The measured phase noise of the standalone QVCO equals -100 dBc/Hz at 1 MHz offset. Since E-band radio links utilize higher order QAM modulation, the bit-error rate is sensitive to I/Q phase error. In the measured standalone QVCO with I/Q phase imbalance detection and compensation, the error is detected in two cross coupled active mixers that have an output DC level proportional to the phase error. The error can then be eliminated adjusting the bias of four varactors connected to the QVCO outputs. The current consumption of the chip equals 14 mA from a 1.5 V supply and 57 mA from a 2.5 V supply dedicated to the detector and 28 GHz output measurement buffers.

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Analytical EVM, BER, and TD performances of the OFDM systems in the presence of jointly nonlinear distortion and IQ imbalance

Zareian

Vakili

2009

Ann. Telecommun.

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The orthogonal frequency-division multiplexing (OFDM) systems are highly sensitive to the nonlinear distortions introduced by the high-power amplifier at the transmitter and to the in-phase and quadrature (IQ) imbalance of the down converter at the receiver. In this paper, the joint effects of these impairments on the performance of the OFDM systems with M signal points quadrature amplitude modulation (M-QAM) are investigated. Moreover, the analytical formulations for the error vector magnitude, the bit error rate, and the total degradation performances of the M-QAM-OFDM systems in additive white Gaussian noise channels as a function of the output back off and IQ imbalance parameters are derived. The computer simulation results confirm the accuracy and validity of our proposed analytical approach.

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Analytical BER Performance of M-QAM-OFDM Systems in the Presence of IQ Imbalance

Cited by 16 publications

References 2 publications

System simulations of a 1.5 V SiGe 81–86 GHz E-band transmitter

System simulations of a 1.5 V SiGe 81–86 GHz E-band transmitter

A 28 GHz SiGe PLL for an 81–86 GHz E-band beam steering transmitter and an I/Q phase imbalance detection and compensation circuit

Analytical EVM, BER, and TD performances of the OFDM systems in the presence of jointly nonlinear distortion and IQ imbalance

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