HSPICE warning while calculating delay times

[vigneshsubbian]

I'm trying to calculate various delay times using .MEASURE COMMAND.
.measure tran trise trig v(1) val = 0.18 rise =1 targ v(1) val = 1.62 rise = 1
.measure tran tfall trig v(1) val = 1.62 fall =1 targ v(1) val = 0.18 fall = 1

I don't seem to get the results. It says,
trise= failed trig= not found
tfall= failed trig= not found

I have a warning saying,

**warning** dc voltage reset to initial transient source value
in source 0:vin new dc= 0.0000D+00
Looks like this warning is the cause but I'm not able to remove it. I have the dc voltage defined as follows
vin 6 0 pulse(0 1.8 1ns 0.1ns 0.1ns 6ns 12ns)

Any suggestions would be greatly appreciated.

Thanks!!!

 

[Fractional-N]

measuring rise/fall time in hspice

you should write as follows:

.measure tran trise trig v(1) val = 0.18 rise =1 targ v(1) val = 0.18 rise = 2

it gives you the period.
if it does not work.
it is simply because no triggering event found in the v(1) waveform. it seems v(1) never reaches 0.18v or does not have a rising edge that passes 0.18v.

some examples from hspice help

Example 1

* Example of rise/fall/delay measurement
.MEASURE TRAN tdlay TRIG V(1) VAL=2.5 TD=10n
+ RISE=2 TARG V(2) VAL=2.5 FALL=2

This example measures the propagation delay between nodes 1 and 2 for a transient analysis. HSPICE measures the delay from the second rising edge of the voltage at node 1 to the second falling edge of node 2. The measurement begins when the second rising voltage at node 1 is 2.5 V and ends when the second falling voltage at node 2 is 2.5 V. The TD=10n parameter counts the crossings after 10 ns has elapsed. HSPICE prints results as tdlay=<value>.

Example 2

.MEASURE TRAN riset TRIG I(Q1) VAL=0.5m RISE=3
+ TARG I(Q1) VAL=4.5m RISE=3
* Rise/fall/delay measure with TRIG and TARG specs
.MEASURE pwidth TRIG AT=10n TARG V(IN) VAL=2.5
+ CROSS=3

In the last example, TRIG. AT=10n starts measuring time at t=10 ns in the transient analysis. The TARG parameters terminate time measurement when V(IN) = 2.5 V on the third crossing. pwidth is the printed output variable.

If you use the .TRAN analysis statement with a .MEASURE statement, do not use a non-zero start time in .TRAN statement or the .MEASURE results might be incorrect.

 

[vigneshsubbian]

hspice measure statement fails

I tried different ways of calculating delays but I don't seem to get them. As you said, the voltage doesn't cross VAL since the warning clearly states that the voltage is set to zero. I don't understand the reason for this warning.!!

Thanks!!

 

[Fractional-N]

hspice: reset to transient

i also receive this warning whenever i put a pulse source in my netlist. but the circuit works . i don't know what this warning means, but it is not the source of your problem. you should look at the transient waveforms; if it doesn't cross the VAL (but it should!) the circuit architecture is wrong. i think the simulations is correct.

use cscope to measure the delay parameters. it is easier.

 

[vigneshsubbian]

hspice .measure tran trig

Ohh OK!! Let me try. Thanks for your help!!