A 5-bit 3.2-GS/s Flash ADC With a Digital Offset Calibration Scheme

作者：Lin Ying Zu^*; Lin Cheng Wu; Chang Soon Jyh

来源：IEEE Transactions on Very Large Scale Integration (VLSI) Systems, 2010, 18(3): 509-513.

DOI：10.1109/TVLSI.2009.2013628

• Digital calibration
• digitally assisted analog-to-digital converter (ADC)
• Flash ADC
• high-speed data converter
• offset calibration

In high-speed Flash analog-to-digital converters (ADCs), preamplifiers are often placed in front of a comparator to reduce metastability errors and enhance comparison speed. The accuracy of a Flash ADC is mainly limited by the random offsets of preamplifiers and comparators. This paper presents a 5-b Flash ADC with a digital random offset calibration scheme. For calibration, programmable resistive devices are used as the loading devices of the second-stage preamplifiers. By adjusting the calibration resistors, the input-referred offset voltage of each comparator is reduced to be less than 1/2 LSB. Fabricated in a 0.13-mu m CMOS process, experimental results show that the ADC consumes 120 mW from a 1.2-V supply and occupies a 0.18-mm active area. After calibration, the peak differential non-linearity (DNL) and integral non-linearity (INL) are 0.24 and 0.39 LSB, respectively. At 3.2-GS/s operation, the effective number of bits is 4.54 b, and the effective resolution bandwidth is 600 MHz. This ADC achieves figures of merit of 3.07 and 4.30 pJ/conversion-step at 2 and 3.2 GS/s, respectively.

• 出版日期2010-3