Title: ComputerAided Verification of Electronic Circuits and Systems
1Computer-Aided Verification of Electronic
Circuits and Systems
- EE219A Fall 2002
- Professor Prof. Alberto Sangiovanni-Vincentelli
- Instructor Alessandra Nardi
2Administration
- Office Hours Th 11.30-13.00 in 545H
- Course mailing list send e-mail to
nardi_at_eecs.berkeley.edu - Course website http//www-cad.eecs.berkeley.edu/
nardi/EE219A
3Grading
- Grading will be assigned on
- Project (? 50 )
- Homework (? 20 )
- Midterm (? 30 )
- There will be approximately 5 bi-weekly homework
and a take-home midterm - No final
4Projects
- Groups of 2 people are strongly recommended
- Tentative schedule
- Make your choice by October 21
- First update October 31
- Second update November 21
- Final presentation December 3 and 5
- May be shared with other classes you are taking
5Major Verification Tasks
Design Concept
Is what I asked for what I want?
Design Verification
Design Description
Is what I asked for what I got?
Synthesis
Implementation Verification
Design Implementation
6Functional Verification
- Specification Validation Are the specifications
consistent? Are they complete, i.e. if the design
satisfies them are we sure that it is correct? - Design Verification Is the entry level
description of my design correct? Most common
reason for chip failure. - Implementation Verification Are the different
levels of abstractions generated by the design
process equivalent?
7Multi-Million-Gate Verification
- Moores Law
- Faster and more complex designs
- Test-vector size grows even faster than design
size - Time-to-market pressures will certainly not abate
- Clearly conflicts with the need to exhaustively
verify a design before sign-off
8Digital Systems Verification Hierarchy
9Verification Techniques
Goal Ensure the design meets its functional (F)
and timing (T) requirements at each of those
levels of abstraction
- Simulation (FT)
- Build a mathematical model of the components of
the design, submit test vectors and solve the
equations that give the output as a function of
the input and of the models on a computer - Formal Verification (F)
- Prove mathematically that
- A description has a set of properties
- Two descriptions at different levels of
abstraction are functionally equivalent
10Verification Techniques
Goal Ensure the design meets its functional (F)
and timing (T) requirements at each of those
levels of abstraction
- Static Timing Analysis (T)
- Analyze circuits topological paths and check
their timing properties and their impact on
circuit delay - Emulation (F)
- Map the design onto the components of the
emulation machine, submit test vectors and check
the outputs of the machine possibly physically
connecting them to a system - Prototyping (F)
- Build a hardware implementation of the design
and operate it
11Simulation Perfomance vs Abstraction
Cycle-based Simulator
Event-driven Simulator
Abstraction
SPICE
Performance and Capacity
12Boolean Simulation Single-Processor
- Event-driven ("time-wheel" or static-ordered)
- Delay Model Emphasis (Inertial or Transport) is
major differentiator. - Today about 20-50K events/sec/Mip
- Cycle-based
13Cycle-based simulation
- Cycle-based simulators work off of a control and
data-flow representation - Treats everything in the design description as
either clocked element or zero-delay
combinational logic - Advantages
- exceptionally fast
- same internal representation for both simulation
and synthesis - predicted results same as synthesized logic
14Cycle-based Algorithm
- Input design must be completely synchronous
- Only evaluate on the clock edge
- First evaluate all combinational logic
- Next latch values into state registers
- Repeat on next clock edge
clock
15Boolean Simulation Hardware Acceleration
- Quickturn-IBM (Cobalt) type
- 1M Event/sec.
- Requires fairly long compilation time
16Emulation
- Based on re-programmable FPGA technology.
- Only functional verification (no timing
verification yet). - Close to implementation performance.
- Can boot operating system, give look and feel for
final implementation. - Allows hardware-software co-design.
17Prototyping Techniques in Design Stages
Hardware Design Changes
Emulation
Cost
Software Simulation
Performance
Prototype Replication
Flexibility
time
18Board Level Rapid-Prototyping Environment
- Early feedback on customers requirements
- Early system integration
- In-field test on vehicle
- Virtual prototyping (co-simulation) and physical
prototyping (emulation board)
19Simulation vs Formal Methods
- Degree of confidence in simulation depends on
test vectors selected by the designers - Formal methods most important for implementation
verification - Simulation cannot be replaced by formal
verification especially for design verification
specifications are often not given in rigorous
terms and are not complete
20Analog Circuits A World Apart
- Analog circuits behavior specified in terms of
complex functions time-domain, frequency-domain,
distorsion, noise, power spectra. - Required accuracy of models much higher than
digital - emerging paradigm Field Programmable Analog
Array for prototyping (and more)
21More on Verification.
- System-on-Chip (SoC) Hardware/Software
Co-Verification - Mixed-Signal Verification
- Physical Issues introduced by DSM technologies
22Classes at Berkeley
23219A Course Overview
- Fundamentals of Circuit Simulation
- Approximately 12 lectures
- Analog Circuits Simulation
- Approximately 4 lectures
- Digital Systems Verification
- Approximately 3 lectures
- Physical Issues Verification
- Approximately 6 lectures
24Circuit Simulation
- Formulation of circuit equations
- STA, MNA
- Solution of linear equations
- LU factorization, QR factorization, Krylov
Methods - Solution of nonlinear equations
- Newtons method
- Solution of ordinary differential equations
- One-step and Multi-step methods
25Analog Circuit Simulation
- AC Analysis and Noise
- Simulation Techniques for RF
- Shooting-Newton
- Harmonic-Balance
26Digital Systems Verification
- Overview
- Cycle-based and event-driven simulation
- Formal methods
- Timing Analysis
- Hardware Description Languages (Verilog-VHDL)
- System C
27Digital Systems Verification Timing Analysis
- Not only has the design to function
properly.it also has always tighter timing
constraints - Design timing properties have
- to be verified
- ? Static Timing Analysis is the main method
28Physical issues verification (DSM)
- Interconnects
- Signal Integrity
- P/G integrity
- Substrate coupling
- Crosstalk
- Parasitic Extraction
- Reduced Order Modeling
- Manufacturability and Reliability
- Power Estimation
29Physical issues verification (DSM)Interconnects
- Scaling technology
- They get longer and longer
- Increasing complexity
- New materials for low resistivity
- ? Inductance and capacitance become more
relevant - Larger and larger impact on the design
- ? Need to model them and include them in the
design choices (gate-centric to
interconnect-centric paradigm)
30Physical issues verification (DSM)P/G and
Substrate
- Analog and Digital blocks may share supply
network and substrate - Can I just plug them together on the same chip?
Will it work? - The switching activity of digital blocks injects
noise current that may kill analog sensitive
blocks
Digital IP
Analog
31Physical issues verification (DSM)Crosstalk
- In DSM technologies, coupling capacitance
dominates interlayer capacitance - ? there is a bridge between interconnects on
the same layer.they interfere with each other!
32Physical issues verification (DSM)Parasitic
Extraction
- Parasitics play a major role in DSM technologies
- Need to properly extract their value and model
33Physical issues verification (DSM)Reduced Order
Modeling
- Increasing complexity ?? bigger and more complex
models - E.g. supply grid, parasitics
- Need to find a reduced model so that
- Still good representation
- Manageable size
34Physical issues verification (DSM)Manufacturabili
ty
- Design a chip
- Send it to fabrication
- .
- Did I account for the fabrication process
variations? - How many of my chips will work?
- Just one? All? Most of them?
- How good is my chips performance?
- ?Design and verification need to account for
process variations!
35Physical issues verification (DSM)Reliability
- Design a chip
- Send it to fabrication
- .
- Did I test my design for different kinds of
stress? - Is it going to work even in the worst case?
- Can I sell it both in Alaska and Louisiana?
36Physical issues verification (DSM)Power
Estimation
- Advent of portable and high-density circuits
- ? power dissipation of VLSI circuits becomes a
critical concern - ?Accurate and efficient power
- estimation techniques are required
37Emerging Paradigm
- Design and Verification Integration (Correct by
Construction Paradigm) - Hardware and Software Co-verification
- ltGone are the days of throwing code "over the
wall" to another group. Productive verification
requires tearing down the wall between design and
verification and between hardware and software.gt - By Tom Fitzpatrick, Co-Design Automation, Inc.,
Los Altos, CA - EETimes, May 28, 2002