| 摘要 |
A low noise DC-DC converter is provided to stably supply output voltage in spite of the variation of power voltage, and to reduce noise due to a switching operation. A low noise DC-DC converter(20) includes a power switch unit(21), an analog-digital converter(23), a digital low frequency filter(22), an error calculator(25), and a switching signal generator(27). The power switch unit receives power voltage and ground voltage, and generates output voltage by switching an output terminal and one of a power voltage terminal and a ground voltage terminal according to a switching signal. The analog-digital converter samples the power voltage and the output voltage, and outputs the sampled voltage as a power level signal and an output level signal. The digital low frequency filter performs low-frequency-filtering for the power level signal and the output level signal. The error calculator compares the low-frequency-filtered power level signal and power level signal, and an output voltage set value, and outputs an error value. The switching signal generator generates the switching signal to control the time for connecting between the one of the power voltage terminal and the ground voltage terminal, and the output terminal according to the error value.
|
