ULTRA LOW POWER FREQUENCY SYNTHESIZER

摘要

An ultra low power frequency synthesizer is provided to obtain the oscillation function of the low frequency and the stability within +/- 250 ppm with satisfying the standby current of the ultra low current at the bluetooth transceiver. An ultra low power frequency synthesizer includes an automatic compensation block and an ultra low power oscillator(30). The automatic compensation block outputs the compensation signal due to the phase difference by comparing the output frequency inputted by the feedback with the reference frequency. The operation of the automatic compensation block is controlled in response to the state of the power down signal at the waiting state which does not require the frequency compensation. The ultra low power oscillator(30) is provided with a charging unit(31), a first oscillation unit(32), a second oscillation unit(33) and an output driving unit(34). The ultra low power oscillator(30) charges and discharges the input voltage controlled in response to the compensation signal and generates the output frequency by oscillating the voltage level of the output node in response to the state of the charged and discharged voltage level.