An 18 b 5 MS/s SAR ADC with 100.2 dB dynamic range

Abstract

This paper presents an 18 bit 5 MS/s SAR ADC. It has a dynamic range of 100.2 dB, SNR of 99 dB, INL of ±2 ppm and DNL of ±0.4 ppm. It has currently the lowest noise floor of any monolithic Nyquist converter relative to the full scale input (21.9 nV/√Hz, ±5V full scale) known to the author, all of this is achieved with an ADC core power of 30.52 mW giving a Schreier figure of merit of 179.3 dB [1]. Architectural choices such as the use of a residue amplifier are outlined that enable the high sample rate, low noise and power efficiency. The design is implemented on 0.18 μm CMOS with MIM capacitors and both 1.8 V and 5 V MOS devices. An LVDS interface is used to transfer the ADC result off chip.