Kyusun Choi, Thesis Advisor/Co-Advisor Vijaykrishnan Narayanan, Committee Member
Keywords:
TIQ Flash ADC TIQ Voltage Comparator Nonlinearity DNL INL Process Variation
Abstract:
Integral nonlinearity and differential nonlinearity are the two main performance
parameters for a high speed flash analog-to-digital converter, which determine the accuracy of the
converter. Analog-to-Digital Converter (ADC) circuits are designed to achieve ideal performance
- zero linearity. However, the linearity is unavoidable due to the process variation, operating
temperature variation, and power supply voltage variation when the data converters are
manufactured and used in non-ideal environments. We present the new and improved transistor
sizing algorithms for the Threshold Inverter Quantization (TIQ) flash comparator circuit design
software package, the sizing algorithm that will results in minimal linearity for the TIQ ADCs
after they are manufactured and used in non-ideal environments. In comparison to the previous
algorithms, the proposed new transistor sizing algorithms reduce the worst-case linearity by 80%
or more. In the future, when implementing ADC circuits with below-30nm CMOS FinFET
technology, the TIQ flash ADC is the first candidate because only two transistors are present
between the power supply rails, and the transistor sizing is based on the discrete count of fins.
