Transcript CREATING IMPLICIT HOMOTOPY METHODS USING HARDWARE

Modeling Safe Operating Area in
Hardware Description Languages
Leonid Goldgeisser
[email protected]
Ernst Christen
[email protected]
Zhichao Deng
[email protected]
Synopsys Inc
2025 NW Cornelius Pass Rd.
Hillsboro, OR, USA, 97124
1.503.547-6118
© 2006 Synopsys, Inc. (1)
Leonid B. Goldgeisser, et al. DAC 2007
1
Predictable Success
Outline
• Safe Operating Area (SOA) concept
 Design reliability vs. Stress
• Requirements for modeling SOA
 Ratings
 De-rating
 Measurements
• Simulation tools are used for functional verification. We
demonstrate that extending simulation tools capabilities to
measure the stress can improve the robustness of a
design. Using MAST and VHDL-AMS HDLs
• Conclusions
2
Safe Operating Areas
• SOA describes the Operating Conditions of the device
operating without self-damage
• SOA often combines various limitations (Constraints) of a
device
Duration of
the current
Junction
Temper
ature
1.SOA Curves for MJL4281A/4302A
3
SOA for Semiconductors
• Limits the voltage, current and temperature.
• Maximum voltage, above which a mechanism such as
avalanche breaks down, will lead to loss of electrical
control.
• Maximum power dissipation, above which the active part
becomes too hot to function correctly.
• Maximum current, above which the interconnect terminal
such as wire contact region can be heated to damage.
4
SOA in Automotive and Aerospace
designs
• Limits the pressure, speed, and torque.
• Maximum speed, above which the moving part can be
damaged.
• Maximum torque, above which the part can suffer due to
the internal forces.
• Maximum pressure, above which the containing part will
be damaged.
5
Need for modeling SOA
Failure to
measure and
model stress
adequately
Reliability suffers
Performance drops:
•Design is too conservative
•Incorporating defense techniques
6
Outline
• Safe Operating Area (SOA) concept
 Design reliability vs. Stress
• Requirements for modeling SOA
 Ratings
 De-rating
 Measurements
• Simulation tools are used for functional verification. We
demonstrate that extending simulation tools capabilities to
measure the stress can improve the robustness of a
design. Using MAST and VHDL-AMS HDLs
• Conclusions
7
Requirements for modeling SOA
• Operating under significant stress levels
shortens the component life.
 Components are tested for allowable stress; the
results usually are reported as rating.
• Ratings are the attributes of the component.
(HDL has to support it).
• The rating represents a boundary of the
SOA for a given device.
 For a reliable design, common sense is to
use components operating sufficiently lower their
ratings, hence the concept of de-rating.
• De-rating is the attribute of the design (The tool has
to support it).
8
Requirements for modeling SOA (Cont’d)
• Robust design implies that no component operates near
or outside of its rated limits.
 All components breaking this rule must be identified.
• A measurement must be taken between the actual value and the
de-rated value.
• The measurement could be performed for all possible types of
analysis -> measuring waveform, values, etc.
• HDL must provide the capability to describe the
measurement.
9
Example
10
Circuit Example, Cont’d
11
Circuit Example, Results
12
SOA Modeling Requirements Digest
1. SOA boundary is associated with a waveform.
2. Should have a name, so a user can select it.
3. Should include a description string to be included in the
stress report.
4. Should provide a way to specify a variety of waveform
measurements.
5. Should include the rating from the manufacturer.
6. Should provide a way to specify a de-rating by the user.
13
Measuring capabilities
•Peak (the maximum
deviation from a reference).
•Minimum allowable value.
•Maximum allowable value.
•Minimum and maximum for a
time interval, integrated over
the interval.
•Average over time.
•RMS for periodic signals.
14
Modeling SOA With MAST® HDL
• The considerations listed above were the basis for the
design of the stress_measure specification.
• Stress_measure(uid, gid, descr, wave, measure, rating, ref_rat)
Unique
Identifier
Group
Identifier
Descript.
String
Measured Measure
Waveform Type
Allowable Reference
Rating
rating
15
Example of Specifying SOA
Boundaries using the MAST Language
template resistor p m = r, vmax,
pmax
control_section {
Name
Group
Descr.
stress_measure(pavg, power,
electrical p, m
number r
“Average power dissipation”,
number vmax = undef
pwrd, average, pmax)
number pmax = undef
stress_measure(pmax, power,
{
rating
Measure
“Maximum power dissipation”,
val i i
pwrd, winmax, pmax)
val v v
stress_measure(vmax, voltage,
val p pwrd
“Maximum voltage“,
abs(v), max, vmax)
v = v(p,m)
i=v/r
pwrd = v * i
}
}
i(p->m) += i
16
SOA Modeling in VHDL-AMS
• No Predefined Language Semantics to capture SOA.
• VHDL provides constructs to capture the SOA
in a model – attributes.
• Since waveforms are represented by quantities in
VHDL-AMS, a SOA boundary is represented by an
(user defined) attribute on a quantity.
• The a value of the user defined attribute combines the
remaining aspects of the SOA boundary.
17
SOA Modeling with VHDL-AMS,
example.
package soa is
-- Declare another set of attributes that
-- Declare a record type to hold all aspects
-- compares the absolute value of the quantity
-- of an SOA boundary
-- with the rating
type soa_boundary is record
attribute stress_abs_minimum: soa_boundary;
description:
rating:
string(1 to 32);
real;
attribute stress_abs_maximum: soa_boundary;
attribute stress_abs_peak:
reference_rating: real;
soa_boundary;
attribute stress_abs_average: soa_boundary;
end record;
attribute stress_abs_rms:
-- Declare the attributes, one for each
attribute stress_abs_winmin: soa_boundary;
-- measurement method, that compares the
attribute stress_abs_winmax: soa_boundary;
-- value of the quantity with the rating
-- Declare a function to help defining an
attribute stress_minimum: soa_boundary;
-- SOA boundary
attribute stress_maximum: soa_boundary;
function soa_value(description: string;
attribute stress_peak:
rating: real;
soa_boundary;
attribute stress_average: soa_boundary;
attribute stress_rms:
soa_boundary;
attribute stress_winmin: soa_boundary;
soa_boundary;
reference_rating: real := 0.0)
return soa_boundary;
end package soa;
attribute stress_winmax: soa_boundary;
18
SOA Modeling with VHDL-AMS
library ieee;
Observations:
use ieee.electrical_systems.all;
 It is possible to have more than
use work.soa.all;
entity resistor is
generic (r: real;
-- resistance value
vmax: real := real’high; -- max. voltage
port (terminal p, m: electrical);
end entity resistor;
architecture simple of resistor is
quantity v across i through p to m;
quantity pwrd: real;
attribute stress_average of pwrd: quantity is
soa_value(“Average power dissipation”, pmax);
attribute stress_winmax of pwrd: quantity is
soa_value(“Maximum power dissipation”, pmax);
attribute stress_abs_maximum of v: quantity is
soa_value(“Maximum voltage”, vmax);
stress related
pmax: real := real’high);-- max. power
one SOA boundary associated
with a quantity.
 Using stress_abs_maximum
instead of stress_maximum
makes the monitoring of the
voltage boundary independent of
the polarity of the voltage without
having to declare an extra
quantity.
 Since the reference rating is 0 for
all three SOA boundaries, there
is no need to specify it.
begin
i == v / r;
pwrd == i * v;
end architecture simple;
19
Conclusions
•
We have demonstrated how measuring the stress by the circuit
simulator can be related to the Safe Operating Area.
• Such measurements facilitate the creation of a robust design.
• We analyzed the requirements for measuring the stress.
• We have shown how those requirements can be translated into
features of a behavioral modeling language and gave examples for
the MAST and VHDL-AMS.
•
We have demonstrated how stress analysis can be used to identify
components operating under excessive amount of stress.
20
Conclusions
• Realization that:
 Ratings:
• Are attributes of the part; must be provided by the manufacturer.
 De-rating:
• Are attributes of the design; must be chosen by the system
designer based on the application of the design.
 SOA modeling:
• Must be either incorporated into or facilitated by the modeling
language.
 Stress Measurement:
• Must be supported by the tool (Simulator).
• Propose a SOA modeling standard for 1076.1 VHDL-AMS
committee.
21