A combo Analog-to-Digital/Analog-to-Multiple-Value converter with configurable resolution

An analog-to-digital converter (ADC) with a configurable 4, 8 or 12-bit resolution is presented in this paper. It is based on a binary tree structure implemented with current-mode circuits whereas an appropriate integer division is performed at the nodes of the tree. The binary representation of the analog input value is produced at the leaves of the tree while its corresponding multi-value representation can be directly retrieved from the intermediate nodes of the tree thus avoiding additional encoding of the binary representation or expensive process technologies and specialized devices that are required by other approaches. The sampling speed of the 12-bit ADC is 140 MS/s and requires only 0.123 mm² of die area in 90 nm CMOS technology while the 6-digit Analog-to-Quaternary Conversion (AQC) achieves 155 MS/s rate.