Transceiver

摘要

A transceiver 1 includes a frequency synthesizer 2 configured to generate an output signal 3 for use as a carrier signal for transmission and/or a signal with a channel frequency for reception, wherein the frequency synthesizer is a sub-sampling based frequency locked loop frequency synthesizer. The combination of a FLL and sub-sampling allows to obtain a sub-sample based locked loop with a closed loop response similar to a PLL but with improved settling time and improved suppression of high frequency components of the quantization noise due to the sampling process. The transceiver allows to obtain a frequency synthesizer with improved characteristics with respect to at least one of power consumption, locking characteristic, design optimization characteristics compared to non-sub-sampling PLL based frequency synthesizers.

主权项

1. A transceiver comprising a frequency synthesizer configured to generate an output signal for use as a carrier signal for transmission and/or a signal with the channel frequency for reception, characterized in that, the frequency synthesizer is a sub-sampling based frequency locked loop frequency synthesizer at which the frequency synthesizer output signal with a frequency fout is directly sampled with sampling frequency fsampling wherein fsampling< wherein the frequency locked loop frequency synthesizer comprises:
a frequency detector unit configured to receive a reference frequency signal fref and a variable frequency signal and to generate a frequency difference output signal, the difference output signal being a function of a difference between a frequency value associated with the reference frequency signal fref and a frequency value associated with the variable frequency signal;a digital-to-analog convertor configured to convert the frequency difference output signal into an analog frequency difference signal;a loop filter unit configured to receive the analog frequency difference output signal and configured to attenuate any signal component above a predetermined frequency to provide a smoothed control signal;a voltage controlled oscillator unit configured to receive the smoothed control signal and to produce an output signal which frequency is a function of the smoothed control signal; anda sampling unit configured to under-sample the output signal with a predetermined sampling frequency fsampling to obtain the variable frequency signal that is applied to the frequency detector unit, wherein the variable frequency signal is a P-bit digital signal, P being a positive integer smaller than 8.