Advances in electronic systems have lead to the demand for high resolution, high bandwidth Analog-to-Digital Converters (ADCs). Oversampled ADCs are well- known for high accuracy applications since they benefit from noise shaping and they usually do not need highly accurate components. However, as a consequence of oversampling, they have limited signal bandwidth. The signal bandwidth (BW) of oversampled ADCs can be increased either by increasing the sampling rate or reducing the oversampling ratio (OSR). Reducing OSR is a more promising method for increasing the BW, since the sampling speed is usually limited by the technology. The advantageous properties (e.g. low in-band quantization, relaxed accuracy requirements of components) of oversampled ADCs are usually diminished at lower OSRs and preserving these properties requires complicated and power hungry architectures.
In this thesis, different combinations of delta-sigma and pipelined ADCs are explored and new techniques for designing oversampled ADCs are proposed. A Hybrid Delta-Sigma/Pipelined (HDSP) ADC is presented. This ADC uses a pipelined ADC as the quantizer of a single-loop delta-sigma modulator and benefits from
the aggressive quantization of the pipelined quantizer at low OSRs. A Noise-Shaped Pipelined ADC is proposed which exploits a delta-sigma modulator as the sub-ADC of a pipeline stage to reduce the sensitivity to the analog imperfection. Three prototype ADCs were fabricated in 0.18μm CMOS technology to verify the effectiveness of the proposed techniques. The performance of these architectures is among the best reported for high bandwidth oversampled ADCs.