A new scheme has been used to linearize the VCO output frequency versus the tuning voltage characteristic, reducing the VCO gain. The PLL can be a 2nd or 3rd order closed loop system depending on the loop filter order. Loop stability is controlled by VCO gain, CP current, Divider and Loop filter values. Noise in a PLL is broadly classified into two categories as phase noise (Random Jitter) and periodic noise (Deterministic Jitter). The source of phase noise is generally thermal noise, flicker noise and shot noise.
So the VCO gain will be higher for broadband PLL to cover the wide tuning range. Now any noise at the input will be amplified by VCO gain and the jitter value will increase. Simulating phase noise and jitter is time-consuming, as these values can only be calculated after PLL simulation has been performed.
In another way, behavioral modeling can be implemented to reduce the simulation time and predict the accurate result for phase noise and jitter. An ideal model is implemented to recheck the effect of non-ideals on the performance of a PLL.
Thesis Outline
Internal noise from the VCO also contributes noise and can change the zero crossing points of the generated signal, resulting in jitter. The acquisition range is the maximum value of the phase error for which an unlocked PLL can eventually reach the locked state. UP=1,DN=0. The circuit remains in this state until CK goes high, after which UP returns to zero.
3-stage NAND-based PFD is a more obvious choice for wideband PLL. The circuit Fig 2.2 can be used in different forms. PLLs act as low-pass filters, so the purpose of the loop filter is to filter out the high-frequency components from the PFD output. The essential idea behind a VCO design is to generate a clock signal based on Barkhausen's swing criteria, which states that the magnitude of the VCO's transfer function at the swing frequency is 1 while the phase is -180 degrees.
Level shifters have been added at the beginning and end of the separation chain to reduce the dynamic force and improve reliability. However, in reality there are residual inconsistencies due to the varactor nonlinearity and the finite rise time of the DAC output voltage, which limits the settling time. The performances mainly phase noise and power consumption of frequency synthesizer implemented in RF-CMOS process is superior to the synthesizer realized in digital CMOS process.
The power consumption of the synthesizer in [7] is 8mW, but the off-chip loop filter is used because of its large capacitance.
CP architecture & design
Conclusion
CP current determines the loop stability and CP non-idealities generate the spur in the PLL. Once the LF order, phase margin, loop bandwidth and pole ratio are chosen, the poles and zero of the filter can be determined.
LOOP FLTER CHOICE
PLL TF WITH LOOP DESIGN PROCEDURE
So PLL acts 1) a low pass filter for the Fin , Fdiv and CP noise 2) high pass for VCO o/p frequency 3) band pass for regiter noise. Therefore bandwidth of the PLL. If we change the BW, we can check the variation in Jitter values. This is experimented below. The formulas for the second order passive loop filter were presented in this chapter.
Transfer functions for each and every noise source have been checked and the BW of the overall system has been chosen accordingly. Jitter can be defined as "the short-term variation of a signal relative to its ideal position in time. To calculate the total jitter, the first step is to model each sub-block of the PLL in cadence.
The PLL scheme with phase noise injection for each sub-block is given in Fig. In theory and with perfect measurement equipment, phase noise measured for an infinite carrier shift would give the same value as jitter. Then all the CSV file generated from PSS will be added to the system shown in Fig. 5.1. After that, the next task is the simulation of noise profile generation after filtering by PLL.
So, at the limit of PLL, design consideration has been taken, considering lower minimum voltage of all power sources. The input noise of crystal inside the LOOP-BW is passed unfiltered and high frequency noise ie 3000 ppm Frequency accuracy of the synthesized clock with respect to target value measured over 100us time.
The post-shared clock with frequency FREQ_pllclkout is issued on pll_clkout_o. The value of pll_fbdiv is provided by integer and fractional registers for FBDIV. Below are some examples of the relationship between the input and output frequency and the multiplication factor. Testing the silicon result::Integer PLL is taped and the silicon result needs to be proven in the future.
Testing the silicon result::Integer PLL has been taped out and silicon result has to be proven in future
Tsukahara, "A 1-V 2.4-GHz PLL synthesizer with a fully differential prescaler and a low-off-leakage charge pump," in Microwave Symposium Digest, 2003 IEEE MTT-S International, June 2003, pp. Razavi, "A Stabilization Technique for Phase-Locked Frequency Synthesizers," in Proceedings of the1999 IEEE International Symposium on Circuits and Systems (ISCAS), June 2003, vol. Huard, "A Fast-Switching PLL Frequency Synthesizer with an Un- chip passive discrete-time loop filter in 0.25-μm CMOS,” Solid-State Circuits, IEEE Journal of, vol.
Kang, “Architecture of a 3.48 mW 2.4 GHz bandgap frequency synthesizer with two-point fast alignment channel control,” in SOC. Lee, "A general theory of phase noise in electrical oscillators," Solid-State Circuits, IEEE Journal of, vol. Maneatis, “Low-Jitter and Process-Independent DLLs and PLLs Based on Self-Biased Techniques,” Solid-State Circuits, IEEE Journal of, vol.
