Simulation Using the Affirma Analog Design Environment

• Using its harmonic balance engine, HSPICE RF offers high-capacity nonlinear, frequency domain simulation capabilities for RFIC and high frequency designs.
Other Simulators
• In addition to Cadence SPICE and Spectre circuit simulator popular analog and microwave simulators can be used through a set of integrated simulation interfaces.
More About Direct Simulation
• Important Benefits of Direct Simulation
– Improved performance in netlisting. – Improved performance of simulation for Spectre. – Readable netlists. – Read only design can be simulated provided that they are extracted. – Improved support of standalone netlisting.
Spice, PSpice and HSpice
• SPICE was originally developed at the Electronics Research Laboratory of the University of California, Berkeley (1975) • PSpice is a PC version of SPICE (MicroSim Corp.) • HSpice is a version (Avant!.) that runs on UNIX workstations and larger computers. This is particularly fast version and one that should be nimulators Eg. Spectre
Socket Simulators Eg. SpectreS, cdsSpice
Direct Simulation Vs Socket Simulation
• Direct Simulation
– This is a preferred method because uses the new features added to Spectre simulator and uses direct simulation. – With direct simulation, the netlist uses the syntax of the simulator w/o any processing to evaluate expressions. – The netlist is a direct reflection of the design.
• RF Capabilities • Mixed Signal Simulation
• Spectre circuit simulator coupled with the Verilog-XL simulator in the AFFIRMA environment can simulate mixed analog and digital circuit
• HSPICE achieves upto 20x speed up for cell characterization applications where speed, power and noise are most important.
• HSPICE RF For High Frequency & RF Designs:
– Eg. Meta Software’s HSPICE circuit simulator, HP’s MNS microwave simulator, Compact Software’s Harmonica microwave simulator.
• We have AFFIRMA HSPICE interface installed on our system. • We do not have a HSPICE simulator installed yet.
• Socket Simulation
– The netlist is processed by Cadence SPICE to evaluate all expressions and resolve passed parameters. – Socket methodology is used to integrate a simulator if the current simulator cannot handle expressions or parameters passing. – Efficient operation in various interactive mode such as simulation stop and restart or change values and resimulate.
Cadence SPICE
• Cadence SPICE simulator is an interactive circuit simulator based on UC Berkley’s SPICE2 program. • Modified architecture for interactive operations plus enhancement that automatically improve convergence with problem circuit. • Can be used within the Analog simulation environment or as a standalone simulator.
Cadence DFII Architecture
HSPICE Simulator
• Gold standard for accurate circuit simulation. • Extensive set of build in devices, models including models for small geometry MOSFET and MESFET. • Compatible with Spice and MSING input format. • Cadence supports a library of primitives and a full interface of HSpice. • High Performance:
• Environment
• Fully integrated into Cadence DFII for AFFIRMA and also in Cadence Analog workbench design system
SPICE compatibility of Spectre
• SPICE is a industry standard language with many variations of SPICE syntax on market today. • Each vendor modifies it with different capabilities and/or slightly different syntax. • For convince of SPICE users AFFIRMA Spectre simulator provides SPICE Reader as an extension to its native language that accepts most variations of SPICE input. • SPICE Reader supports SPICE2, SPICE3, and common extensions found in other simulators like PSPICE and HSPICE.
• Signal Integrity:
• HSPICE simulates enhanced W – elements and extracted S – parameters for accurate signal integrity analysis of PCB’s.
Inverter Example
Improvements of Spectre over SPICE
• Improved Capacity
• Can simulate larger circuit.
• Improved Accuracy
• Improved component models and core simulator algorithms
Simulators in the Affirma Analog Design Environment
Sachin Shinde Xiaolai He
• Cadence design framework II environment consists of many Cadence tools which are interoperable without requiring data conversion. • DFII is an open system allowing the user to integrate third party tools like simulators using programmable netlister or enter their own design data.