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Where To Find This Example

AWR Version 14

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AWR Version 13

This example was renamed since the previous version. Please see Previous Example Page for the version 13 page.

Design Notes

Frequency Divider with Phase Noise

The Frequency Divider is a fundamental building block in most RF/analog ICs.  The purpose of this example is to illustrate the phase noise simulation of a standard frequency divider in the AWR Design Environment.

This project also shows the Phase Noise calculation for moving the offset frequencies to baseband using the output equations.  


Schematic:  div2 test PN

Time Domain (Signal Analysis)

This schematic is set up to allow the AWRDE to analyze phase noise of the same frequency divider sub-circuit used in the time domain schematic.   The only difference here is the use of the MMCONV blocks to convert the input signal to differential and back again at the output.  The waveforms shown in the graph titled "Transient Response" are the input and output signals shown differentially.  The graph titled “Transient Response Comparison” shows the same signal but one is analyzed with HSPICE while the other uses HB time domain analysis.  They are nearly identical except for very subtle differences.  The spectrum of these signals is plotted in the graph titled "Divider Output Spectrum".  Here we observe the spectrums of the signals analyzed with 2 different simulation engines are identical.

Frequency Domain (Phase Noise Analysis)

The NLNOISE block wants to have a single input and output port defined to measure noise.  In addition, the measurement PH_NOISE_NL_F plots the phase noise at the carrier seen on the graph titled "div2 PN at carrier Freq".  In this example, we show a way to plot the phase noise at baseband which is done with the equations in the Global Definitions and Output Equations.  The result can be seen on the graph titled "Phase Noise Response".

Output Equations

The output equation "PN_fx" is an arbitrarily chosen measurement that has the carrier frequency as its x-axis.  "PN_off" plots the standard phase noise measurement results (see "div2 PN at carrier Freq" graph) against an x-axis that is shifted by the carrier frequency.

Schematic - div2_test_PN

Graph - Divider Output Spectrum

Graph - div2 PN at carrier Freq

Graph - Phase Noise Response