A pseudo-2bit 4-GSps flash ADC in 0.18µm CMOS for an IR-UWB communication system

This paper presents a novel pseudo-2bit 4GS/s flash analog-to-digital converter (ADC) for an OFDM Impulse Radio Ultra Wide Band (IR-UWB) receiver. Comparing to traditional 2bit flash ADC, it saves a comparator and an encoder. In this ADC, all the signals both in the analog part and the digital part are differential and low swing. A serial-to-parallel module is designed to speed down the output data rate and a Low Voltage Differential Signaling (LVDS) interface circuit has been designed to achieve the data rate as high as 500MSps. The core of the proposed ADC dissipates 26mW power from a 1.8V supply while operating at 4GHz. This chip has been fabricated in 0.18μm 1P6M CMOS process.