Engineering digital design (2nd ed.)
Engineering digital design (2nd ed.)
Advanced Engineering Mathematics: Maple Computer Guide
Advanced Engineering Mathematics: Maple Computer Guide
A randomized wrapped-around pulse position modulation scheme for DC-DC converters
IEEE Transactions on Circuits and Systems Part I: Regular Papers - Special section on 2009 IEEE custom integrated circuits conference
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We present a micropower digital modulator for class-D amplifiers for power-critical digital hearing aids. The modulator design embodies a proposed Lagrange interpolation (a combined first- and second-order Lagrange) algorithmic pulsewidth modulation (PWM) and a third-order ΔΣ noise shaper. By means of double-Fourier-series analysis, we analyze and determine the harmonic nonlinearities of the proposed algorithmic PWM. At 48-kHz sampling, 96-kHz PWM output, 997-Hz input, and input modulation index = 0.9, the modulator circuit achieves a total harmonic distortion + noise (THD + N) of -74 dB (0.02%) over an 8-kHz voice bandwidth--a 12-dB THD + N improvement over a reported design and yet dissipates only ∼50% of the power. The proposed modulator dissipates the lowest power dissipation of all modulators compared, and by means of a proposed figure of merit, the proposed modulator exhibits very competitive performance. The modulator IC is fabricated in a 0.35-µm digital CMOS process with a core area of 0.46 mm2.