| 摘要 |
PROBLEM TO BE SOLVED: To reduce a leak current of a current source transistor(TR) in a charge pump circuit of a PLL circuit. SOLUTION: A charge pump circuit of this PLL circuit that is activated by an UP signal or a DOWN signal generated by a phase lead or phase lag between a reference clock and a VCO output clock to produce a charging current or a discharge current to an LPF at the input of the VCO, consists of a current source transistor(TR) 12 that produces a charging current to the LPF, of a switching TR 11 that connects the current source TR 12 to a power supply in response to an UP signal, a current source TR 13 that produces a discharge current flowing from the LPF, and a switching TR 14 that connects the current source TR 13 to ground in response to a DOWN signal. Furthermore, a back gate bias is given to the current source TRs 12, 13 when the charge pump circuit is deactivated. |
