In phase locked loop, dither ring null dither of output of the generator which is controlled

摘要

The generator where PLL is controlled digitally (DCO), as the DCO_OUT signal had the frequency which at the interval which dither is done changes, dither it is done. With one example, as for DCO, dither of the digital tuning word which comes entering the stream which is not done is received, the standard clock pulse REFD which dither is done is received, the DCO_OUT signal is output, the frequency change has reached the point where it happens at the interval which dither is done. When it can use PLL with the local generator of the transmitter of the cellular telephone, the new dither ring of DCO diffuses, in order digital image noise, with the frequency offset of specification from main local generator frequency, to decrease, digital image noise frequency. It becomes possible to satisfy the specification of noise, with the frequency diffusion of digital image noise, without necessary to increase the frequency of the PLL standard clock. Evading the increase of frequency of the standard clock, increase of consumption of power is evaded by satisfying the specification of noise.