Patent attributes
The digital-to-analog converter in accordance with the present invention comprises an R-2R transistor-only ladder converter and a digital controller. The controller connects to the R-2R transistor-only ladder converter and comprises at least one regulating transistor and at least one shifting transistor. The at least one regulating transistor has an aspect ratio of kR(W/L). The at least one shifting transistor has an aspect ratio of kS(W/L). Setting the aspect ratios kR(W/L) and kS(W/L) of the shifting and regulating transistors adjusts a linear output current waveform to a non-linear waveform. The method to output a non-linear current comprises acts of determining an optimum non-linear output current, dividing a linear output current into multiple sections, determining slopes of the waveform of the output current, adding a controller corresponding to an R-2R transistor-only ladder converter, setting aspect ratios kR(W/L) of regulating transistors and setting an aspect ratios kS(W/L) of shifting transistors.
