Methodology and comparative design of an efficient 4-bit encoder with bubble error corrector for 1-GSPS flash type ADC

摘要

The design of a 4-bit encoder with a bubble error correction of first order is described in this study. Since encoder restricts speed of the flash analogue-to-digital converter (ADC), therefore, an improved and faster encoder is an essential requirement to push its limits. Encoder is divided into two parts: one-hot code generator [or bubble error corrector (BEC)] and binary encoder. Binary encoder proposed in this study is the modified Fat-Tree encoder of types I and II. Three types of BECs which have been compared in this study are OR gate based, NAND gate based and the proposed BEC. The proposed BEC consumes less power and provides better speed as compared to NAND based and OR gate based BECs. It can be further employed for higher order bubble correction as well. The proposed BEC consumes dynamic power of 87.071 mu W and leakage power of 18.3563 pW exhibiting the delay of 38.3 ps with 1.8 V supply voltage and 1 GHz clock frequency. It has a power-delay product of 3.335 fJ, energy-delay product of 127.7305 Js and an intrinsic area of 4.753 mm(2).