This thesis presents a novel current-controlled oscillator (CCO). It charges and discharges a source-coupled capacitor periodically with well-controlled current sources. Its current-to-frequency conversion relies on passive components, which are insensitive to the temperature and process variations. The proposed CCO is compact and area-efficient. Moreover, compared to ring-oscillator and LC-tank oscillator, it exhibits much wider tuning range and better linearity. Therefore, it suits the modern system-on-chip (SoC) design. / text

abstract: Pulse Density Modulation- (PDM-) based class-D amplifiers can reduce non-linearity and tonal content due to carrier signal in Pulse Width Modulation - (PWM-) based amplifiers. However, their low-voltage analog implementations also require a linear- loop filter and a quantizer. A PDM-based class-D audio amplifier using a frequency-domain quantization is presented in this paper. The digital-intensive frequency domain approach achieves high linearity under low-supply regimes. An analog comparator and a single-bit quantizer are replaced with a Current-Controlled Oscillator- (ICO-) based frequency discriminator. By using the ICO as a phase integrator, a third-order noise shaping is achieved using only two analog integrators. A single-loop, singlebit class-D audio amplifier is presented with an H-bridge switching power stage, which is designed and fabricated on a 0.18 um CMOS process, with 6 layers of metal achieving a total harmonic distortion plus noise (THD+N) of 0.065% and a peak power efficiency of 80% while driving a 4-ohms loudspeaker load. The amplifier can deliver the output power of 280 mW. / Dissertation/Thesis / Ph.D. Electrical Engineering 2011