A high speed low power encoder for a 5 bit flash ADC

The present investigation proposes an efficient low power encoding scheme intended for a 5GS/s 5 bit flash analog to digital converter. The designing of a thermometer code to binary code is one of the challenging issues in the design of a high speed low power flash ADC. An encoder circuit in this paper translates the thermometer code into the intermediate gray code to reduce the effects of bubble errors. To maintain the high speed with low power dissipation, the implementation of the encoder through pseudo NMOS logic is presented. The proposed encoder is designed using 90nm technology in 1.2 V power supply using CADENCE tool. The simulation results shown for a sampling frequency of 5GHz and the average power dissipation of the encoder is 0.3149 mW which is very less in comparison with current mode logic encoder implementation.

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