This thesis presents a discrete-time dynamic zoom analog-to-digital converter (ADC) for low-frequency sensor applications. The proposed zoom ADC consists of a 6-bit asynchronous successive-approximation-register (SAR) ADC, a second-order delta-sigma m...
This thesis presents a discrete-time dynamic zoom analog-to-digital converter (ADC) for low-frequency sensor applications. The proposed zoom ADC consists of a 6-bit asynchronous successive-approximation-register (SAR) ADC, a second-order delta-sigma modulator, a digital logic block incorporating data-weighted averaging (DWA), and a kT/C noise cancellation block. By employing the kT/C noise cancellation technique, the required sampling capacitance can be significantly reduced. This reduction not only alleviates the driving load of the front-end stage but also decreases the capacitor-array area and the dynamic power required to drive the sampling capacitors. As a result, the proposed zoom ADC achieves an effective resolution exceeding 16 bits with a sampling capacitance of only 2.2 pF.
The proposed zoom ADC was implemented in a 180-nm CMOS process with a 1.8-V supply voltage and occupies an active area of 0.296 mm². It operates at a sampling frequency of 512 kHz and achieves an oversampling ratio (OSR) of 512 for a signal bandwidth of 500 Hz. The ADC consumes 286.3 µW of power. For a 100-Hz sinusoidal input signal, the measured peak signal-to-noise-and-distortion ratio (SNDR) is 98.34 dB. The measured dynamic range (DR) is 103.51 dB.