Unless otherwise stated, all rights belong to the author. Two loop filters are designed, one for loop bandwidth approximately 1 MHz and another for loop bandwidth approximately KHz. VCO start-up and stability analysis using time varying root locus. The aspect ratio of the cross-coupled NMOS transistor of the VCO cores varied quite a bit from the calculated value which provided a guideline. Since for the source follower the source is the output node, the transistor becomes dependent on the body effect. The ring oscillator is a commonly used oscillator for integrated PLLs and clock recovery circuits because it is less complex and easy to integrate.
The main disadvantage to using this configuration is the difficulty in implementing it when the supply quadraturf is low due to the stacking of transistors. Resistors R1, R2 and R3 shown in Figure 3. Each differential input variable is connected to a differential pair circuit.
Electrical and Computer Engineering. However, it is important to note that in general, an array of switched-capacitors can be used to achieve a larger tuning range. I would qiadrature like to thank Dr. The combined task of the PFD, charge pump, and loop filter blocks is to provide a stable DC tuning voltage to the VCO quadraure on the frequency and phase difference between the reference frequency and output of the divider so that acquisition of the PLL can be achieved.
Finally, the loop filter is the component most commonly used to control system-level loop dynamics . Therefore, the phase noise of the VCO is mainly determined by the overall quality factor Q of the circuit .
For symmetry, the 32 switched-capacitor block is implemented using two capacitors and two transistors. Higher order PLL transfer functions are based on this, however are much more complex. Analog and Digital Signal Processing, pp. For a given current, this complementary topology offers higher transconductance. This feature of PLLs proves useful in many applications such as radio, computers, telecommunications and other electronic applications . The VCO with the switched capacitor turned on will be designed to cover the frequency range of approximately The proper design of the loop filter is also important for the stability of the PLL loop .
The additional pole must be lower than the reference frequency in order to significantly attenuate the spurs, but it must be at least 5 times higher than the loop bandwidth, or else the loop will become unstable.
UBC Theses and Dissertations. In general, the tail current aids the designer in achieving a compromise between phase noise performance and power dissipation. Therefore, we need something to turn the current produced by the charge pump back into a voltage. In communication systems a good-quality LO signal for quadrahure and down-conversion in transmitters is needed.
Permanent address of the item is http: The delays of the components must match, and if they do not match the delay difference results in dead zone.
A PMOS current quadrathre which has better phase noise performance with reduced flicker noise was used . Initial simulations indicated that the target tuning range was not possible for this design with only one switched-capacitor for a fair comparison, so the goal was altered to maximize tuning range.
The amount of delay in the PFD reset path is the key parameter to the dead zone. Yordanov, “Wireless inter-chip and intra-chip communication,” in Microwave Conference European,pp. This quadratur because settling time is inversely proportional to bandwidth.
Integrated RF oscillators and LO signal generation circuits
Master’s theses – Open access. This structure maintains a constant energy in the ring to avoid pattern-dependent power droop. A low pass filter may be needed for additional rejection of reference sidebands called spurs .
Comparison of these results to simulation results is thezis, indicating that overall the results match approximately and show the same trend. The appropriate value of the delay was initially chosen by trial and error.
Quadrature vco thesis
In general, the capacitance of the varactors is made small compared to the capacitance quadeature the capacitors so the varactors have a larger effect on the htesis capacitance, which consists of two capacitors and two varactors in series, allowing for a larger frequency range.
Closed-loop PLL simulations for two loop bandwidths, 1 MHz and kHz, using a simple charge pump, PFD, loop filter, and Verilog-A divider confirm that settling time is inversely proportional to bandwidth. Abstract Integrated circuit scaling has enabled a huge growth in processing capability, which necessitates a corresponding increase in inter-chip communication bandwidth.