What is the difference between MMCM and PLL?

What is the difference between MMCM and PLL?

The phase relationship between the PLL output clock and the input clock is positional, but MMCM can choose to align the input and output phases. At the same time, PLL has only two output clocks, while MMCM has six. The core of the DCM is the DLL, that is, the delayed Locked Loop. …

What is Xilinx PLL?

This application note and reference design provide a digital phase-locked loop (DPLL) solution that utilizes spare resources in a Virtex™-4 FPGA and requires minimal external components. The performance of the DPLL is superior to most integrated mixed-signal solutions.

What is DCM and PLL?

The PLL is an analog clock management cell that can do almost everything the DCM can do with the exception of dynamic and fine phase shifting. However, it can do more precise frequency generation and can generate multiple different frequencies at the same time.

What is Bufgce?

Clock Routing Resources Overview BUFGCE is for glitchless clock gating and has software derivative BUFG (BUFGCE with clock enable tied High). The global clock buffers drive routing and distribution tracks into the device logic via HCS rows. There are 24 routing and 24 distribution tracks in each HCS row.

What is dynamic reconfiguration port?

Dynamic Reconfiguration port (DRP) The Dynamic reconfiguration port that is an integral part of each functional block which greatly simplifies the process of reconfiguration. This allows the user to dynamically change the clock outputs while the design is running.

What is PLL FPGA?

The Phase-Locked Loop (PLL) is a closed-loop frequency-control system that compares the phase difference between the input signal and the output signal of a voltage-controlled oscillator (VCO). The negative feedback loop of the system forces the PLL to be phase-locked.

What is DCM in Xilinx?

The Digital Clock Manager (DCM) primitive in Xilinx FPGA parts is used to implement delay locked loop, digital frequency synthesizer, digital phase shifter, or a digital spread spectrum. The digital clock manager module is a wrapper around the DCM primitive which allows it to be used in the EDK tool suite.

What are DCM’s why they are used?

applications. DCMs optionally multiply or divide the incoming clock frequency to synthesize a new clock frequency. DCMs also eliminate clock skew, thereby improving system performance. Similarly, a DCM optionally phase shifts the clock output to delay the incoming clock by a fraction of the clock period.

How do I use Xilinx Clocking Wizard?

FPGA Clocking: Clocking Wizard in Xilinx ISE

  1. Create a Xilinx ISE Project.
  2. Add VHDL Source Code.
  3. Verify your ucf file.
  4. Run the clocking wizard to generate your desired clocks.
  5. Instantiate clocks into your project.
  6. (Optional) Make design easier to share by removing *. xco file.

What is clock management tiles?

The clock management tiles (CMT) provide clock frequency synthesis, deskew, and jitter filtering functionality.


FPGAs are often used to provide a custom solution in situations in which developing an ASIC would be too expensive or time-consuming. Of course, the flexibility of the FPGA comes at a price: An FPGA is likely to be slower, require more PCB area and consume more power than an equivalent ASIC.

What does the DCM, mmcm and PLL do?

Re: DCM, MMCM and PLL. The DCM is a Digital Clock Manager – at its heart it is a Delay Locked Loop. This has the ability to deskew a clock, generate different phases of the clock, dynamically change the phase of a clock, generate related (2x) clocks, do clock division, and even generate clocks with harmonic relationships to the incoming clock.

Can you fine phase shift in mmcm and PLL?

Fine-phase shifting is not allowed for the initial configuration or during reconfiguration. The MMCM and PLL Configuration Bit Groups section presents the configuration bits as five bit groups, and provides an overview of their usage. The DRP Registers section details the configuration bit locations as registers.

How is the delay time counter used in mmcm?

This means that there is a direct correlation between the possible phase shift for the clock output and the divide value for that particular output. As the divide value increases, finer phase shift steps are available. The Delay Time counter allows for a phase offset of up to 64 VCO clock cycles.

What are the six bit groups in mmcm?

The MMCM has six user-accessible configuration bit groups that allow reconfiguration of individual clock outputs. The six groups are the divider group, the phase group, the fractional group, the lock group, the filter group, and the power group.

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