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Jitter Voltage Source with Arbitrary, User-Specified Bit Sequence: V_JITTER

Symbol

Summary

V_JITTER is a voltage source (two terminal device) that can only be used in transient simulations. It is essentially derived from the PORT_ARBS (but made to be an ideal two-terminal voltage source) with the most general specification of the deterministic jitter, and random jitter with Gaussian distribution added to it. The jitter type is selectable using the JITTER_TYPE parameter (so you can get deterministic jitter, random jitter, or both).

Parameters

Name Description Unit Type Default
ID Element ID Text V1
Rate Frequency (project units) GHz 1
SEQ Bit vector of length N   (1,0,1,0)
SAMP Integer number   128
LOW Voltage value V 0
HIGH Voltage value V 1
SignalingType RZ or NRZ   NR2
TR Time in project units    
TF Time in project units    
JITTER_TYPE (Deterministic, Random, Both)   Deterministic
RE_DELTA Vector of time values of length N ns (0,0,0,0)
FE_DELTA Vector of time values of length N ns (0,0,0,0)
MEAN_R Time value in project units ns 0
SIGMA_R Time value in project units ns 0
MEAN_F Time value in project units ns 0
SIGMA_F Time value in project units ns 0
CONST_WIDTH (Yes, NO)   yes
SEED Random number generator seed   -1

* indicates a secondary parameter

Parameter Details

Rate. Symbol Rate

SEQ. Bit sequence

SAMP. Samples per symbol: Used only for harmonic balance simulation. For this type of source, a SAMP on the order of approximately 128 is expected. Thus HB simulations are likely to succeed only for linear circuits (Fourier analysis), and will diverge for strongly nonlinear circuits.

LOW. Low voltage value.

HIGH. High voltage value.

Signaling Type. Waveform type.

TR. Rise time.

TF. Fall time.

JITTER_TYPE. Specifies the type of jitter to be added.

RE_DELTA. Increment of the rising edge start time.

FE_DELTA. Increment of the rising edge start time.

MEAN_R. Mean value of delta for the rising edge.

SIGMA_R. Gaussian distribution width for the rising edge.

MEAN_F. Mean value of delta for the falling edge.

SIGMA_F. Gaussian distribution width of the falling edge.

CONST_WIDTH. If Yes, maintain constant pulse width. This means that exactly the same deterministic and random numbers are used to modify the start of the falling edge as were used to modify the start of the rising edge. The values specified for the rising edge win over those for the falling edge.

SEED. If SEED >=1, the value used to seed the random number generator with Gaussian distribution. If SEED<0, the last tick of the CPU clock is used to seed the random number generator. In this case, random numbers are truly random (not repeatable).

Implementation Details

The V_ JITTER source is closely related to PORT_ARBS with the following differences:

(1) It is a two-terminal voltage source rather than one-terminal port.

(2) The instances of time when the rising and falling edges start is affected by user- specified vectors RE_DELTA (for the rising edge) and FE_DELTA (for the falling edge). Let tRk (k=1, ..., N) be the time instance when the leading edge of the bit k starts in PORT_ARBS, and tFk be the time instance when the falling edge begins in PORT_ARBS. In Jitter_D source, the rising edge of bit k begins at tRk+RE_DELTA[k]+ R[k], and the falling edge begins at tFk+FE_DELTA[k]+ F[k]. R[k] and F[k] are pseudo-random numbers corresponding to the realizations of Gaussian processes with mean and sigma specified above. If JITTER_TYPE=Random, RE_DELTA and FE_DELTA are ignored. Similarly, if JITTER_TYPE=Deterministic, no random process is generated. Thus the vectors RE_DELTA and FE_DELTA provide the most general description of deterministic jitter, and MEAN_ and SIGMA_ specify the Gaussian random processes for the start time of the rising and falling edge.

Layout

This element does not have an assigned layout cell. You can assign artwork cells to any element. See “Assigning Artwork Cells to Layout of Schematic Elements” for details.

Usage

To use deterministic jitter, you must generate a data file with 3 columns (bit value, rising edge delay, and falling edge delay) and import it into Cadence® AWR® Microwave Office® software. This allows for specifying the desired deterministic functions that could be calculated in a tool other than AWR Microwave Office software (like MathCad and Matlab and exported into a file).

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