作为抖动滤波器,通常假设PLL为缓冲器,并在时钟输出端口上再生输入频率。通常将BANDWIDTH属性设为Low能实现更大的抖动滤波,但会导致PLL的静态偏移增大。 2.5 限制 PLL在VCO工作范围、最小和最大输入频率、占空比、相移等方面有一些限制。 VCO工作范围:详见DS202.Table 74.PLL Specification。 最小和最大输入频率:详见...
The constant loop bandwidth over the above tuning frequency ranges is achieved without modifying low pass filter parameters. The current of charge pump \\(Icp\\) is programmed not only to compensate the variation of voltage-controlled oscillator gain \\(Kvco\\) , but also for adapting to the...
The design of this block can be dominated by either of these considerations, or can be a complex process juggling the interactions of the two. Typical trade-offs are: increasing the bandwidth usually degrades the stability or too much damping for better stability will reduce the speed and incre...
This book explores the architectures of blocks which contribute for the low jitter adaptive bandwidth charge pump PLL. PLLs have wide applications for Frequency Synthesis, where the output of PLL is a multiple of the frequency of the input reference signal. For low jitter operation, proper ...
A loop filter’s bandwidth can be doubled by doubling either the PFD frequency or the charge-pump current. If the actual Kv of the VCO is significantly higher than the nominal Kv used to design the loop filter, the loop bandwidth will be significantly wider than expected. The variation of...
A wider loop bandwidth will result in a faster response time, but it can also make the PLL more susceptible to noise. The loop bandwidth is determined by the values of the charge pump current, the loop filter capacitor, and the loop filterresistor. The following equation shows the ...
The lower the bandwidth, the longer it takes to acquire the lock. The PLL damping coefficient, which influences overshoot and speed, is usually 1/√(2) or 1. Bandwidth The bandwidth refers to the frequency range in which the PLL functions, as well as the frequency range in which the PLL...
PLL-charge pump
4.2.2. Programmable Bandwidth with Advanced Parameters An advanced level of control is also possible for precise control of the PLL loop filter characteristics. This level allows you to explicitly select the following advanced parameters: • Charge pump current (charge_pump_current) • Loop ...
in order to attenuate its high frequency content before it feeds into the loop filter opamp. The reason for doing so is that the opamp has limited bandwidth and can exhibit nonlinear behavior if it is directly driven with the high frequencies that are present in the charge pump output. The ...