J.Semicond.2010,31(7) Meng Lingbu et al. Latch Latch VDD R M13 DI CLK CLK M M2 VSS Fig.9."NAND"embedded CML D-flip-flop. Phase Noise 10,00dB/Ref -10.00dBc/Hz -10.0 -20.0 Loop PFD -30.0 EC/ -40.0 Filter CP -50.0 -60.0 -70.0 -80.0 90.0 DO -100.0 Digital -110.0 120.0 Prescaler -130.0 140.0 150.0 160.0 -170.0 GVN3B Fig.10.Die photograph Fig.11.Measured phase noise at an oscillation frequency of2.26 GHz. Single-stage multiple feed forward SDM is adopted herelio.Fewer output levels of SDM are preferred so as to lower the in-band phase noise deterioration through noise fold- N mode and integer-N mode respectively.The RMS phase ing by quantization noise going through analog blocks with error is less than 0.7 in integer-N mode and less than 1 in non-linearity fractional-N mode across the overall tuning range.Table 1 lists the performance comparison with other frequency synthesizers 4.Experimental results for tuner applications.Comparing with other frequency synthe- sizers for tuners applications,the presented frequency synthe- The frequency synthesizer was fabricated in SMIC 0.18- sizer achieves superior phase noise performance and low power um CMOS technology.The chip microphotograph is shown in consumption. Fig.10.The die area of the frequency synthesizer is about 1.2 Figure 13 shows the measured power spectrum density ×0.8mm2. (PSD)of the oscillation amplitude at 2.3 GHz;the reference Operating at 2.2 GHz,the frequency synthesizer draws 10 spur is-66 dBc.Figure 14 shows the reference spurs at differ- mA from 1.8-V supply.The measured loop bandwidth is ap- ent output frequencies.The reference spur is less than-63 dBc proximately 100 kHz.The measured phase noise plots for the in across the overall tuning range. frequency synthesizer are shown in Fig.11.In-band phase noise at 10 kHz offset is-95 dBc/Hz and at 1 MHz offset the 5.Conclusion measured phase noise is-111 dBc/Hz.The integrated RMS phase error is 0.8.Figure 12 shows the measured RMS phase A fractional-N frequency synthesizer for DTV tuner ap- error integrated from 100 Hz tol00 MHz in both fractional- plications has been presented in this paper.Transfer func- 075007-5J. Semicond. 2010, 31(7) Meng Lingbu et al. Fig. 9. “NAND” embedded CML D-flip-flop. Fig. 10. Die photograph. Single-stage multiple feed forward SDM is adopted hereŒ10. Fewer output levels of SDM are preferred so as to lower the in-band phase noise deterioration through noise fold￾ing by quantization noise going through analog blocks with non-linearity. 4. Experimental results The frequency synthesizer was fabricated in SMIC 0.18- m CMOS technology. The chip microphotograph is shown in Fig. 10. The die area of the frequency synthesizer is about 1.2 0.8 mm2 . Operating at 2.2 GHz, the frequency synthesizer draws 10 mA from 1.8-V supply. The measured loop bandwidth is ap￾proximately 100 kHz. The measured phase noise plots for the frequency synthesizer are shown in Fig. 11. In-band phase noise at 10 kHz offset is –95 dBc/Hz and at 1 MHz offset the measured phase noise is ￾111 dBc/Hz. The integrated RMS phase error is 0.8ı . Figure 12 shows the measured RMS phase error integrated from 100 Hz to100 MHz in both fractional￾Fig. 11. Measured phase noise at an oscillation frequency of 2.26 GHz. N mode and integer-N mode respectively. The RMS phase error is less than 0.7ı in integer-N mode and less than 1ı in fractional-N mode across the overall tuning range. Table 1 lists the performance comparison with other frequency synthesizers for tuner applications. Comparing with other frequency synthe￾sizers for tuners applications, the presented frequency synthe￾sizer achieves superior phase noise performance and low power consumption. Figure 13 shows the measured power spectrum density (PSD) of the oscillation amplitude at 2.3 GHz; the reference spur is –66 dBc. Figure 14 shows the reference spurs at differ￾ent output frequencies. The reference spur is less than –63 dBc in across the overall tuning range. 5. Conclusion A fractional-N frequency synthesizer for DTV tuner ap￾plications has been presented in this paper. Transfer func- 075007-5