A 6bit, 1.2GSps low-power flash-ADC in 0.13 μm digital CMOS

A 6 bit flash-ADC with 1.2 GSps, wide analog bandwidth and low power, realized in a standard digital 0.13 μm CMOS copper technology is presented. Employing capacitive interpolation gives various advantages when designing for low power: no need for a reference resistor ladder, implicit sample-and-hold operation, no edge effects in the interpolation network (as compared to resistive interpolation), and a very low input capacitance of only 400 fF, which leads to an easily drivable analog converter interface. Operating at 1.2 GSps the ADC achieves an effective resolution bandwidth (ERBW) of 700 MHz, while consuming 160 mW of power. At 600 MSps we achieve an ERBW of 600 MHz with only 90 mW power consumption, both from a 1.5 V supply. This corresponds to outstanding figure-of-merit numbers (FoM) of 2.2 and 1.5 pJ/convstep, respectively. The module area is 0.12 mm².