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Charge Pump

Output a current proportional to the difference in duty cycle between two input ports

  • Library:
  • Mixed-Signal Blockset / PLL / Building Blocks

Description

The Charge Pump block produces an output current which is proportional to the difference in duty cycles between the signals at its up and down input ports. In a phase-locked loop (PLL) system, the Charge Pump block converts the phase error as represented by the two outputs of the PFD block into a single current at the input to the Loop Filter.

Ports

Input

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Input port, connected to the up output of a PFD in a PLL system.

Data Types: double

Input port, connected to the down output of PFD in a PLL system.

Data Types: double

Output

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Output port, connected to the Loop Filter block in a PLL system. out delivers current proportional to the difference in duty cycles between up and down input ports.

Data Types: double

Parameters

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Configuration

Full scale magnitude of design output current, specified as a scalar in A.

Programmatic Use

  • Use get_param(gcb,'OutputCurrent') to view the current value of Output current.

  • Use set_param(gcb,'OutputCurrent',value) to set Output current to a specific value.

Logic switching threshold at input ports, specified as a scalar in V.

Programmatic Use

  • Use get_param(gcb,'InputThreshold') to view the current value of Input threshold.

  • Use set_param(gcb,'InputThreshold',value) to set Input threshold to a specific value.

Select to enable increased buffer size during simulation. This increases the buffer size of the Logic Decision and Slew Rate inside the Charge Pump block. By default, this option is deselected.

Number of samples of the input buffering available during simulation, specified as a positive integer scalar. This sets the buffer size of the Logic Decision and Slew Rate inside the Charge Pump block.

Selecting different simulation solver or sampling strategies can change the number of input samples needed to produce an accurate output sample. Set the Buffer size to a large enough value so that the input buffer contains all the input samples required.

Dependencies

This parameter is only available when Enable increased buffer size option is selected in the Configuration tab.

Programmatic Use

  • Use get_param(gcb,'NBuffer') to view the current value of Buffer size.

  • Use set_param(gcb,'NBuffer',value) to set Buffer size to a specific value.

Impairments

Select to add circuit impairments to simulation. By default, this option is deselected.

Difference between full scale positive and negative current, specified as a scalar in A.

Dependencies

To enable this parameter, select Enable Impairments in the Impairments tab.

Programmatic Use

  • Use get_param(gcb,'CurrentImbalance') to view the current value of Current imbalance.

  • Use set_param(gcb,'CurrentImbalance',value) to set Current imbalance to a specific value.

Output current when both inputs are at logic zero, specified as a scalar in A.

Dependencies

To enable this parameter, select Enable Impairments in the Impairments tab.

Programmatic Use

  • Use get_param(gcb,'LeakageCurrent') to view the current value of Leakage current.

  • Use set_param(gcb,'LeakageCurrent',value) to set Leakage current to a specific value.

Determines how output step size is calculated.

  • Select Default to calculate output step size from rise/fall time parameter.

  • Select Advanced to calculate output step size from maximum frequency of interest parameter.

Dependencies

To enable this parameter, select Enable Impairments in the Impairments tab.

Maximum frequency of interest at the output, specified as a real positive scalar in Hz.

Dependencies

  • To enable this parameter, select Enable Impairments in the Impairments tab.

  • This parameter is only available when Advanced is selected for Output step size calculation.

Programmatic Use

  • Use get_param(gcb,'MaxFreqInterest') to view the current value of Maximum frequency of interest.

  • Use set_param(gcb,'MaxFreqInterest',value) to set Maximum frequency of interest to a specific value.

up

20%-80% rise/fall time for up input port.

Dependencies

To enable this parameter, select Enable Impairments in the Impairments tab.

Programmatic Use

  • Use get_param(gcb,'RiseFallUp') to view the current value of up Rise/fall time.

  • Use set_param(gcb,'RiseFallUp',value) to set up Rise/fall time to a specific value.

Total propagation delay for up input port, specified as a scalar in s.

Dependencies

To enable this parameter, select Enable Impairments in the Impairments tab.

Programmatic Use

  • Use get_param(gcb,'PropDelayUp') to view the current value of up Propagation delay.

  • Use set_param(gcb,'PropDelayUp',value) to set up Propagation delay to a specific value.

down

20%-80% rise/fall time for down input port.

Dependencies

To enable this parameter, select Enable Impairments in the Impairments tab.

Programmatic Use

  • Use get_param(gcb,'RiseFallDown') to view the current value of down Rise/fall time.

  • Use set_param(gcb,'RiseFallDown',value) to set down Rise/fall time to a specific value.

Total propagation delay for up input port, specified as a scalar in s.

Dependencies

To enable this parameter, select Enable Impairments in the Impairments tab.

Programmatic Use

  • Use get_param(gcb,'PropDelayDown') to view the current value of down Propagation delay.

  • Use set_param(gcb,'PropDelayDown',value) to set down Propagation delay to a specific value.

More About

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References

[1] Banerjee, Dean. PLL Performance, Simulation and Design. Indianapolis, IN: Dog Ear Publishing, 2006.

[2] Gardner, Floyd M. Phaselock Techniques. Hoboken, NJ: John Wiley & Sons, Inc. 2005.

See Also

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Introduced in R2019a