Abstract
Filterless digital class D power amplifiers usually utilize three-level uniform sampling pulse width modulation (UPWM) technique to convert the digital input signal into a UPWM signal which is used to drive the power stage. Therefore, the spectral estimation expressions for different three-level UPWM signals obtained by modulating the digital signal can be an evaluation tool for signal distortion and electromagnetic interference when filterless digital class D power amplifiers are designed. Based on the time-domain characteristics of three-level UPWM signals, the spectral estimation expressions for six types of three-level UPWM signals are proposed in this paper by using the discrete Fourier transform technique and the frequency response of the zero-order holder. According to these expressions, the relationships among the total harmonic distortion, the pulse repetition frequency and the pulse width resolution of the UPWM signal are studied. A UPWM generator test system based on field-programmable gate array is designed and implemented to measure the spectra of different UPWM signals. The measured results are compared with the calculated results obtained by the proposed expressions to verify the correctness of the proposed expressions.
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References
H.S. Black, Modulation Theory (Van Nastran, New York, 1953), pp. 263–281
X. Chen, H. Qu, Z. Yu, C. Zhang, E. Zhang, A filterless digital audio class-D amplifier based on grow-left double-edge pulse width modulation, in Proceedings of the 2017 2nd IEEE International Conference on Integrated Circuits and Microsystems (2017), pp. 231–235
Z. Galias, X. Yu, On zero-order holder discretization of delayed sliding mode control systems, in Proceedings of the 2014 IEEE International Symposium on Circuits and Systems (2014), pp. 1255–1258
T. Ge, J.S. Chang, Filterless class D amplifiers: power-efficiency and power dissipation. IET Circuits Devices Syst. 4(1), 48–56 (2010)
J.M. Goldberg, M.B. Sandler, Noise shaping and pulse-width modulation for an all-digital audio power amplifier. J. Audio Eng. Soc. 39(6), 449–460 (1991)
F. Guanziroli, R. Bassoli, C. Crippa, D. Devecchi, G. Nicollini, A 1 W 104 dB SNR filter-less fully-digital open-loop class D audio amplifier with EMI reduction. IEEE J. Solid State Circuits 47(3), 686–698 (2012)
L. Guo, T. Ge, J.S. Chang, A 101 dB PSRR, 0.0027% THD + N and 94% power-efficiency filterless class D amplifier. IEEE J. Solid State Circuits 49(11), 2608–2617 (2014)
C. Jin, M.T. Tan, K.Y. See, Filterless class-D amplifier with pseudorandomized carrier frequency modulation for EMI reduction. IEEE Trans. Electromagn. Compat. 55(1), 74–80 (2013)
M. Johansen, K. Nielsen, A review and comparison of digital PWM methods for digital pulse modulation amplifier (PMA) systems, in Proceedings of the 107th AES Convention (1999), preprint 5039
T. Karaca, M. Auer, G. Winkler, B. Deutschmann, Impact of spread spectrum EMI-reduction on audio performance of filterless class-D amplifiers, in Proceedings of the 22nd Austrian Workshop on Microelectronics (2014), pp. 47–52
Y.-J. Lin, W.-R. Liou, M.-L. Yeh, A high efficiency filter-less class-D audio power amplifier, in Proceedings of the 2019 IEEE 8th International Conference on ASIC (2009), pp. 1062–1065
J. Ma, X. Wang, F. Blaabjerg, L. Harnefors, W. Song, Accuracy analysis of the zero-order hold model for digital pulse width modulation. IEEE Trans. Power Electron. 33(12), 10826–10834 (2018)
P.F. Miaja, A. Rodriguez, J. Sebastian, R.G. Ayestaran, On the estimation of the spectrum of discrete pulsewidth modulated signals, in Proceedings of the 2014 IEEE 15th Workshop on Control and Modeling for Power Electronics (2014), pp. 1–10
P. Pracný, I.H.H. Jørgensen, E. Bruun, System-level power optimization of digital audio back end for hearing aids. Circuits Syst. Signal Process. 36(6), 2441–2458 (2017)
Z. Song, D.V. Sarwate, The frequency spectrum of pulse width modulated signals. Signal Process. 83(10), 2227–2258 (2003)
K. Tsakalis, N. Vlassopoulos, G. Lentaris, D. Reisis, A control-theoretic approach for efficient design of filters in DAC and digital audio amplifiers. Circuits Syst. Signal Process. 30(2), 421–438 (2011)
S.-H. Yang, Y.-H. Yang, K.-H. Chen, Y.-H. Lin, T.-Y. Tsai, S.-R. Lin, C.-C. Lee, A low-THD class-D audio amplifier with dual-level dual-phase carrier pulsewidth modulation. IEEE Trans. Ind. Electron. 62(11), 7181–7190 (2015)
Z. Yu, Y. Fan, L. Shi, G. Lv, A pseudo-natural sampling algorithm for low-cost low-distortion asymmetric double-edge PWM modulators. Circuits Syst. Signal Process. 34(3), 831–849 (2015)
Acknowledgements
This work is supported by the National Natural Science Foundation of China (Grant No. 61601411), the Science and Technology Project of Henan Province (Grant Nos. 192102210243, 182102210607 and 192102210108) and the Doctoral Scientific Research Foundation of Zhengzhou University of Light Industry (Grant No. 2015BSJJ008).
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Yu, Z., Zhang, E., Chen, X. et al. Spectral Analysis of UPWM Signals for Filterless Digital Class D Power Amplifiers. Circuits Syst Signal Process 39, 2094–2117 (2020). https://doi.org/10.1007/s00034-019-01250-7
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DOI: https://doi.org/10.1007/s00034-019-01250-7