محمد غلامی

Nowadays, one of the most important blocks in telecommunication circuits is the frequency synthesizer and the frequency multipliers. Phase-frequency detectors are the inseparable parts of these circuits. In this paper, it has been attempted to design two new structures for phase-frequency detectors in QCA nanotechnology. The proposed structures have the capability of detecting the phase differences of the rising edge or falling edge of their inputs. Also, it can detects frequency differences of its two inputs. In the design of proposed PFDs D flip-flop with few number of cells, area and low delay is used. The proposed PFD circuits in QCA technology have 159 quantum cells, 0.2 μm2 of occupied area, and 1 clock cycle delay for reset path. In comparison to the previous PFD in QCA technology, the proposed designs have ability to detect phase differences more than half of the period of reference signal. That means the capture range of them are approximately 4π (between -2π to 2π). Also, the power simulation of the proposed structures of phase-frequency detector is presented in this paper.