Abstract
Aiming at correcting the error caused by the nonlinear and power supply noise of the bridge-tied-load (BTL) power stage of the filterless digital class D power amplifier, an error correction method was proposed based on feedforward power supply noise suppression (FFPSNS) and first-order closed loop negative feedback (FCLNF) techniques. This method constructed the first-order LCLNF loop for the power stage and further reduced the impact of the power supply noise on the power amplifier output by using FFPSNS technology to introduce the power supply noise into the feedback loop at the same time. The 0.35 μm CMOS process is used for analysis and comparison in Cadence. Cadence simulation results indicate that PSRR at the power supply noise frequency of 200 Hz is improved with 36.02 dB. The power supply induced intermodulation distortion (PS-IMD) components are decreased by approximately 15.57 dB and the signal-to-noise ratio (SNR) of the power amplifier is increased by 17 dB. The total harmonic distortion + noise (THD + N) of the power amplifier is reduced to 0.02% by FCLNF + FFPSNS.
Highlights
In recent years, the country has promoted high-efficiency and energy-saving technologies and encouraged the strengthening of high-efficiency and energy-saving technological transformations and key technological breakthroughs
Digital class D power amplifiers have received increasing attention due to their advantages of high power efficiency, easy system transplantation, and resistance to external interference [3]. e traditional digital class D power amplifier is usually composed of a digital switching signal modulator, a power stage, and an inductive capacitor (LC) analog lowpass filter. e digital switching signal modulator mostly uses uniform-sampling pulse width modulation (UPWM) technology realization. e LC low-pass filter of the traditional digital class D power amplifier occupies about 75% of the volume of the entire power amplifier system and consumes about 30% of the cost, which severely hinders the portable application of digital class D power amplifiers [4]
Under the same experimental conditions, the two correction schemes were compared and analyzed. e results show that compared with the uncorrected power level, the performance of power supply rejection ratio (PSRR) at 200 Hz source noise frequency is improved by 36.02 dB after first-order closed loop negative feedback (FCLNF) correction. e power supply-induced intermodulation Distortion (PS-IMD) component was approximately reduced by 34.73 dB
Summary
The country has promoted high-efficiency and energy-saving technologies and encouraged the strengthening of high-efficiency and energy-saving technological transformations and key technological breakthroughs. E traditional digital class D power amplifier is usually composed of a digital switching signal modulator, a power stage, and an inductive capacitor (LC) analog lowpass filter. Is paper designs a first-order closed-loop negative feedback (FCLNF) error correction method for the filter-free digital class D audio power amplifier bridge-tied-load (BTL) power stage and the FCLNF suitable for the filter-free digital class D audio power amplifier BTL power stage plus feedforward power supply noise suppression (FCLNF + FFPSNS) error correction method. Filter-free digital class D audio power amplifier is mainly composed of digital UPWM modulator and BTL power stage.
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