Worst case delay measurement

Dear Aalelai,

The cross() function in the Calculator may be used with a waveform to determine the time at which the waveform crosses a specific voltage threshold. One of its options allows you to select the slope of the waveform at which it crosses and a second option allows you to select which edge number of the waveform to use to determine the crossing time.

Its options from the ocean reference manual follow. You may also use the cross function in combination with the clip() function to window the output of your delay cell to only consider the time after the input edge to the delay cell is applied to guarantee your propagation delay time is positive. I hope this helps.

Shawn

cross

cross(

o_waveform

n_crossVal

x_n

s_crossType

[ g_multiple [ s_Xname ] ]

)

=> o_waveform / g_value / nil

Description

Computes the X-axis value at which a particular crossing of the specified edge type of the

threshold value occurs.

Gets the time value (X axis) corresponding to specified voltage "/net9"=2.5V (Y axis) for

the second rising edge.

-------------------------

Arguments

Value Returned

Example

cross( v( "/net9" ) 2.5 2 ’rising )

o_waveform Waveform object representing simulation results that can be

displayed as a series of points on a grid. (A waveform object

identifier looks like this: srrWave:XXXXX.)

n_crossVal Y-axis value at which the corresponding values of X are

calculated.

x_n Number that specifies which X value to return. If x_n equals 1,

the first X value with a crossing is returned. If x_n equals 2, the

second X value with a crossing is returned, and so on. If you

specify a negative integer for x_n, the X values with crossings

are counted from right to left (from maximum to minimum). If

you specify x_n equals to 0, it returns all occurrences of the

crossing events.

s_crossType Type of the crossing.

Valid values: ’rising, ’falling, ’either.

g_multiple An optional boolean argument that takes the value nil by

default. If set to t, the value specified for the x_n argument is

ignored and the function returns all occurrences of the crossing

event.

s_xName An optional argument that is used only when g_multiple is

set to t. It takes the value time by default. It controls the

contents of the x vector of the waveform object returned by the

function.

Valid values: ’time, ’cycle

o_waveform Returns a waveform if the input argument is a family of

waveforms.

g_value Returns the X-axis value of the crossing point if the input

argument is a single waveform.

nil Returns nil and an error message otherwise.

----------

Example

cross( v( "/net9" ) 2.5 2 ’rising )

Gets the time value (X axis) corresponding to specified voltage "/net9"=2.5V (Y axis) for

the second rising edge.

cross( v( "/net9" ) 1.2 1 ’either )

Gets the time value (X axis) corresponding to specified voltage "/net9"=1.2V (Y axis) for

the first edge, which can be a rising or falling edge.

cross(VT("/out") 2.5 0 0 t "time") (s)

Returns multiple occurrences of crossing events specified against time-points at which each

crossing event occurs.

cross(VT("/out") 2.5 0 0 t "cycle") (s)

Returns multiple occurrences of crossing events specified against cycle numbers, where a

cycle number refers to the n’th occurrence of the crossing event in the input waveform.

Thank you shawn

There's also the delay function in the calculator too...

Andrew

There's also the delay function in the calculator too...

Andrew