To provide a control circuit of a current mode DC-DC converter, a current mode DC-DC converter and a control method thereof having excellent high-speed responsiveness with respect to fluctuations in output voltage. In particular, such method includes incorporating certain modified nucleotides referred to as Simtides into nucleic acid strands. Several programmable current sinks are described for presenting loads according to a preferred test-waveform current. At runtime, calling contexts access the information.