1 / 18

VHDL-AMS

VHDL-AMS. VHDL- Analog and Mixed Signal Extensions. Overview. IEEE Std. 1076.1-1999: Extension to VHDL to support the description and simulation of analog and mixed-signal circuits and systems VHDL-AMS = IEEE Std. 1076.1-1999 + IEEE Std. 1076-1993

kevinellis
Download Presentation

VHDL-AMS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. VHDL-AMS VHDL-AnalogandMixedSignalExtensions

  2. Overview • IEEE Std. 1076.1-1999: • Extension to VHDL to support the description and simulation of analog and mixed-signal circuits and systems • VHDL-AMS = IEEE Std. 1076.1-1999 + IEEE Std. 1076-1993 • VHDL-AMS is a strict superset of IEEE Std. 1076-1993 • Any model valid in VHDL 1076 is valid in VHDL-AMS and yields the same simulation results

  3. Why Needed? • Many of today’s designs include at least some continuous characteristics: • System design • Mixed-signal electrical designs (Cell phones, …) • Mixed electrical/non-electrical designs (Music players, Digital Cameras, Samand) • Modeling design environment (Temperature, humidity, …) • Analog design • Analog behavioral modeling and simulation • Digital design: As frequency increases, and technology advances (DSM effects), digital circuits become more analog • Clock distribution (PLL’s, pulse shapers, oscillators) • Pad design (buffers, protection circuits) • Interconnect (become more like transmission lines) • Logic cells (become more like RF and microwave circuits) • Designers want a uniform description language

  4. When Digital Becomes Analog? Frequency (GHz)

  5. Issues in Mixed-Signal Circuit Design • As feature size decreases, RF circuit issues become dominant in both digital and analog circuits • Noise • Coupling noise • Component noise • Power supply and ground noise • Circuit parameters • Impedance mismatches • Gain •  Major need for analysis methods and tools

  6. Current Status of Mixed-Signal Design • Fabrication technology: • Current technology supports mixed-signal circuits on a chip • And even mixed electro-mechanical systems on a chip (MEMS) • Design tools: • Analog and Mixed-Signal (AMS) modeling and simulation • AMS synthesis (still in research stage)

  7. Advantages of Verification • Advantages of Modeling and Simulation: • Early error detection • Fine tuning the design based on verification output • Reliable time metrics can be obtained

  8. Simulation in an M-S Environment • Challenges: • Multiple domains, multiple abstraction levels • Simulation cycle handles notion of time in discrete and continuous values • Separate simulation engines, working with the same set of signals

  9. Highlights of VHDL-AMS • Inclusion of continuous valued “quantities” • Allows design entry at the behavioral or structural levels • Analog solution based on numerical integration • Continuous models based on “differential algebraic equations” (DAE)

  10. Nature • Definition: • Nature represents a physical discipline/energy domain • Samples: • Electrical • thermal, • fluidic, • magnetic, • ….

  11. Terminal • Terminal: • Represents a node in an electrical circuit

  12. Quantity • Represents an unknown in the set of DAEs • May be the value (e.g. voltage level) across or through two terminals. • Continuous-time waveform. • For any quantity Q, the attribute name Q’Dot denotes the derivative of Q w.r.t. time. • Q’Dot is itself a quantity • Q’Integ: integral of Q w.r.t. time.

  13. Simultaneous Statement • Simultaneous Statement: • Expresses relationship between quantities. • Analog solver is responsible for computing the values of the quantities such that the relationships hold (subject to tolerances) • May appear anywhere a concurrent statement may appear. • Statement is symmetrical w.r.t. its LHS and RHS. architecture H2 of Vibration is ... begin x1’dot’dot == -f*(x1 - x2) / m1; x2’dot’dot == -f*(x2 - x1) / m2; xs == (m1*x1 + m2*x2)/(m1 + m2); energy == 0.5*(m1*x1’dot**2 + m2*x2’dot**2 + f*(x1-x2)**2); end architecture H2;

  14. Simultaneous Statement • Other Forms of Simultaneous Statements: • Simultaneous IF statement • Simultaneous CASE statement • Simultaneous procedural statement – functions ENTITY sfgAmp IS GENERIC ( gain: REAL := REAL’HIGH); PORT (QUANTITY input: IN REAL; QUANTITY output: OUT REAL); END ENTITY sfgAmp; ARCHITECTURE ideal OF sfgAmp IS BEGIN IF gain /= REAL’HIGH USE output == gain * input; ELSE input == 0.0; END USE; END ARCHITECTURE ideal;

  15. Branch Quantities • Declared between two terminals • Plus terminal and minus terminal • Minus terminal defaults to reference terminal of nature • vd is an across quantity: • it represents the voltage between terminals anode and cathode • vd= vanode - vcathode • id and ic are through quantities: • they represent the currents in the two parallel branches • Both currents flow from terminal anode to terminal cathode architecture Level0 of Diode is quantity vd across id, ic through anode to cathode; ... begin ... end architecture Level0;

  16. Example: Diode library IEEE, Disciplines; use Disciplines.electrical_system.all; use IEEE.math_real.all; entity Diode is generic (iss: REAL := 1.0e-14; n, af: REAL := 1.0; tt, cj0, vj, rs, kf: REAL := 0.0); port (terminal anode, cathode: electrical); end entity Diode; architecture Level0 of Diode is quantity vd across id, ic through anode to cathode; quantity qc: charge; constant vt: REAL := 0.0258; -- thermal voltage begin id == iss * (exp((vd-rs*id)/(n*vt)) - 1.0); qc == tt*id - 2.0*cj0 * sqrt(vj**2 - vj*vd); ic == qc’dot; end architecture Level0;

  17. Quantities in Various Natures • Electrical • voltage: across • current: through • Translational • position: across • force: through • Thermal • temperature: across • power (or heat-flow): through • Fluidic • pressure: across • flow-rate: through

  18. References • Reference Site: • http://www.vhdl-ams.org/ • Reference Book: • The System Designer's Guide to VHDL-AMS (The Morgan Kaufmann Series in Systems on Silicon) by Peter J. Ashenden, Gregory D. Peterson, Darrell A. Teegarden • Tools: • Mentor Graphics SystemVision: • a downloadable version for educational purposes: • www.mentor.com/SystemVision • University of Cincinnati VHDL-AMS simulator (SEAMS) • Infineon Technologies VHDL-AMS Environment • Analogy TheHDL Mixed Signal Simulator • FTL Systems VHDL-AMS Compiler/Simulator • LEDA VHDL-AMS Front-end tools • University of Southampton VHDL-AMS Analyzer • University of Frankfurt Java VHDL-AMS Parser • Models: • http://www.ececs.uc.edu/~dpl/

More Related