Buffer, frequency synthesizer and radio frequency reader writer

The invention relates to a buffer, a frequency synthesizer and a radio frequency reader writer. The buffer comprises a buffering analog amplifying unit used for carrying out analog amplifying on an input signal and a buffering digital output unit which is used for digitalizing the input signal subjected to the analog amplifying and generating a frequency division signal. Compared with the prior art, the buffer in the technical scheme of the invention has the advantages that a gating signal can be selected by closing the buffering analog amplifying unit, and the analog amplifying is realized on the gating signal; then gradual driving on the gating signal can be realized by virtue of the buffering digital output unit, and fan-out capability is improved, thus power consumption is reduced and chip area is saved.