Abstract: The invention discloses DC-DC converters comprising an inductance, a pulse width modulator generating a pulse signal according to the voltage level of a transformed voltage output terminal, a load sensor sensing a load current, an adaptive enable signal generator generating a PMOS transistor enable signal and an NMOS transistor enable signal based on the pulse signal and the load current, and a power transistor set comprising at least one PMOS transistor and an NMOS transistor. The power transistor set is used in coupling the transformed voltage output terminal to an original DC voltage source or ground via the inductance. The conductance of the PMOS and NMOS transistors are controlled by the PMOS and NMOS transistor enable signals, respectively. The adaptive enable signal generator makes a first dead-time between the PMOS and NMOS transistor enable signals decreasing with increasing load current.

Abstract: A vertical complementary fractal antenna is provided, which includes a first fractal structure and a second fractal structure. The first fractal structure is defined as a superposition over at least one iteration of a motif, while the second fractal structure has a pattern complementary to that of the first fractal structure. Thus, the antenna may effectively increase bandwidth.