| 摘要 |
A spread spectrum clock generation circuit and a controlling method thereof are disclosed, which provide clocks having less jitter and ideal spread spectrum and enable a reduction in circuit scale and in power consumption. To this end, a current control type modulator (19a) is equipped with a current source (Ia) (current 4i). A charger unit (CGa) and a discharger unit (DGa) are designed such that currents i, 2i and 4i are allowed to flow, for example, by properly setting the sizes of transistors. Modulation cycles CIa to CIIIa are repeated and an output code is generated from a switching control circuit 20a according to each modulation cycle. A switching unit (SSa) is controlled according to the output code, thereby charging or discharging a capacitor element (Cl) with a charge/discharge current CDI corresponding to the output code. Hence, charge amounts and discharge amounts for all the modulation cycles CIa to CIIIa have the same value, i.e., 6i [A · clock]. |
