Temperature insensitive ultra low power 0.7 V supply input and reference driver for 8 Bit ADC In 65 Nm CMOS technology

With CMOS technology scaling down, performance of ADCs has been improving in terms of area, low supply voltage and especially ultra-low power consumption. How- ever, analog performance has not been advancing compared to progress of the digital performance as CMOS technology is scaling down. This causes the design of ultra-low power ADC input driver still challenging due to its analog architecture. Settling time requirements, ADC input capacitance, low noise and THD requirements limits perfor- mance of ADC input driver for ultra-low power operation. On the other hand, off-chip drivers lead to usage of larger area unnecessarily. This thesis offers the design of an on-chip temperature insensitive, ultra-low power input and reference driver for 8 bit ADC with 0.7 V supply. Temperature insensitivity is an essential feature for temper- ature measurement to avoid the degradation of ADC performance as the temperature varies. The proposed design is able to drive 8 bit ADC along operating temperature range (from -40◦C to 125◦C). The proposed ADC input driver performs single ended to differential signal conversion, buffering, amplitude scaling, output common-mode adjustment and filtering. In the thesis, an ultra-low power 0.7 V supply temperature sensor operating from -40◦C and 125◦C and 100 kSPS differential input SAR ADC with 1V full scale input range is used. ADC reference driver is configured as current controlled non-inverting unity gain buffer between bandgap reference circuit and ADC reference voltage pin. According to the post-layout simulation results, average power consumption over operating temperature range is 111.53 µW. As a worst case scenario, total output noise voltage is 1.418 mV at -40 ◦C. The input driver has a THD of -72.51 dB at 244 Hz and -70.88 dB at 976 Hz.