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Conventional chopper conditioning amplifiers with a differential architecture are largely inappropriate for the monolithic infrared sensing systems with the requirements of single-ended architecture, low power, and yet low noise and low offset. In this paper, a novel chopper amplifier is proposed to satisfy all the aforesaid requirements. This is achieved by means of a novel chopper demodulator that not only incurs no hardware overhead but also inherently suppresses noise and offset. On the basis of computer simulations, the proposed chopper amplifier features very low input referred noise (15nV/ Hz), very low input referred offset (0.2μV), high Signalto-Noise Ratio (~87dB) and high Common Mode Rejection Ratio (98dB), and dissipates low quiescent current (57.6 A). When compared to reported differential chopper amplifiers, the proposed amplifier depicts very competitive Figure-OfMerit.

The specifications of an earphone/headphone audio amplifier typically include high-fidelity (including Signal-to-Noise Ratio  90dB, Total Harmonic Distortion + Noise  80dB and Power Supply Rejection Ratio  70dB), in part due to the psychoacoustic effects of donning earphones/headphones and to the requirement of the single-ended output. Despite the power-efficiency () advantage of Class D amplifiers (CDAs) and their increasing acceptance in general audio applications, they remain largely unacceptable as earphone/headphone amplifiers because their fidelity are insufficient. Not unexpectedly, earphone/headphone amplifiers, at this juncture, are presently predominately Class AB amplifiers, and to the best of the author's knowledge, there is no reported commercial CDA appropriate for earphones/headphones (for mobile applications). We propose the design of a novel single-ended output Class D earphone/headphone amplifier based on the complete-feedback self-oscillation architecture. The complete feedback approach is advantageous over conventional ('incomplete feedback') CDAs because the LC lowpass filter now constitutes part of the feedback loop, and the nonlinearities thereof are mitigated by (Loop Gain + 1). The self-oscillation approach exploits the phase lag of the LC lowpass filter, thereby reducing the hardware complexity of the CDA. The novelty of the proposed design includes an integrator-cum-control block that provides high loop gain and a well-defined oscillation frequency. These attributes effectively mitigate the nonlinearities, including the high