The present invention provides a method (100) of designing a circuit. The method comprises specifying (105) a design parameter for memory transistors and logic transistors and selecting (110) a test retention-mode bias voltage for the memory transistors. The method further comprises determining (115) a first relationship of a retention-mode leakage current and the design parameter at the test retention-mode bias voltage and obtaining (120) a second relationship of an active-mode drive current and the design parameter. The first and second relationships are used (125) to assess whether there is a range of values of the design parameter where the retention-mode leakage current and the active-mode drive current are within a predefined circuit specification. The method also includes adjusting (130) the test retention-mode bias voltage and repeating the determining and the using if the retention-mode total leakage current or the active-mode drive current is outside of the predefined circuit specification.