Using active components to perform voltage division in digital-to-analog conversion

The design of a voltage-mode digital-to-analog (D/A) converter using only fabrication steps required by MOSFETs is described. The converter is implemented using a basic-circuit-building block called the three-input amplifier (TIAMP), which can perform voltage addition and voltage division by 2 without using any passive component. The technique has been used to implement a 12 bit D/A converter for which five samples were tested with accuracies ranging from 6 to 10 bits. Accuracy is limited in the present design by the relatively small sizes chosen for the input transistors. The maximum conversion rate of the present prototypes has been measured to be approximately 1 MHz with a static power dissipation of 50 mW