Complex Bandpass   AD Modulator Architecture without I, Q-Path Crossing Layout

San, Hao; Hayakawa, Akira; Jingu, Yoshitaka; Wada, Hiroki; Hagiwara, Hiroyuki; Kobayashi, Kazuyuki; Kobayashi, Haruo; Matsuura, Tatsuji; Yahagi, K.; Kudoh, Junya; Nakane, Hideo; Hotta, Masao; Tsukada, T.; Mashiko, Kunihiro; Wada, Atsushi

doi:10.1093/ietfec/e89-a.4.908

Cited by 4 publications

(1 citation statement)

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“…However, the performance of the complex bandpass ΔΣAD modulator suffers from the mismatches between internal analog I and Q paths. Mismatches between forward I and Q paths cause an image signal, and the quantization noise of the mirror image band aliases into the desired signal band, which degrades the modulator SQNDR [2]. By providing an extra notch placed at the center of the image band, the SQNDR degradation due to I and Q paths mismatch can be reduced [3], [4].…”

Section: Introductionmentioning

confidence: 99%

Noise-Coupled Image Rejection Architecture of Complex Bandpass .DELTA..SIGMA.AD Modulator

San

Kobayashi

2010

IEICE Trans. Fundamentals

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This paper proposes a new realization technique of image rejection function by noise-coupling architecture, which is used for a complex bandpass ΔΣAD modulator. The complex bandpass ΔΣAD modulator processes just input I and Q signals, not image signals, and the AD conversion can be realized with low power dissipation. It realizes an asymmetric noise-shaped spectra, which is desirable for such low-IF receiver applications. However, the performance of the complex bandpass ΔΣAD modulator suffers from the mismatch between internal analog I and Q paths. I/Q path mismatch causes an image signal, and the quantization noise of the mirror image band aliases into the desired signal band, which degrades the SQNDR (Signal to Quantization Noise and Distortion Ratio) of the modulator. In our proposed modulator architecture, an extra notch for image rejection is realized by noise-coupled topology. We just add some passive capacitors and switches to the modulator; the additional integrator circuit composed of an operational amplifier in the conventional image rejection realization is not necessary. Therefore, the performance of the complex modulator can be effectively raised without additional power dissipation. We have performed simulation with MATLAB to confirm the validity of the proposed architecture. The simulation results show that the proposed architecture can achieve the realization of image-rejection effectively, and improve the SQNDR of the complex bandpass ΔΣAD modulator.

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Section: Introductionmentioning

confidence: 99%