Scilab Function
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closedloop - synthesizer closed loop transfert function

Library

• modnum_pll - Phase Locked Loop utility functions

Description

Compute the closed-loop transfert function of a frequency synthesizer of a second order loop of type 2, defined as :

$$B\left(s\right) = \frac{G\left(s\right)}{1+G\left(s\right)H\left(s\right)},$$

with G(s) the transfert function of the direct gain and H(s) the transfert function of the feedback gain :

$$G\left(s\right) = K_{\rm v}K_{\rm cp}\frac{F\left(s\right)}{s},$$

$$H\left(s\right) = \frac{1}{N},$$

with Kv the sensitivity of the VCO in rad/v, Kcp the PFD gain in A/rad, F(s) the transfert function of the loop filter and N the value of the feedback divider.

Calling Sequence

B = closedloop(F,kv,Icp,N)

Parameters

• F : polynomial defining the transfert function of the loop filter.
• kv : real. local sensitivity of the Voltage Controlled Oscillator [Hz/V]
• Icp : real. maximum charge pump output current [A]
• N : integer. feedback divider value
• B : polynomial defining the transfert function of the closed loop

File content

• MODNUMSCI/macros/pll/closedloop.sci [view code]

See Also

• openloop - synthesizer open loop transfert function (Scilab Function)

Authors

A. Layec A. Layec

Bibliography

[1] U. Rhode, Digital PLL Frequency Synthesizers.Prentice Hall, 1983.