# VHDL-AMS

**VHDL-AMS** is a derivative of the hardware description language VHDL (IEEE standard 1076-1993). It includes analog and mixed-signal extensions (AMS) in order to define the behavior of analog and mixed-signal systems (IEEE 1076.1-1999).

The VHDL-AMS standard was created with the intent of enabling designers of analog and mixed signal systems and integrated circuits to create and use modules that encapsulate high-level behavioral descriptions as well as structural descriptions of systems and components.^{[1]}

VHDL-AMS is an industry standard modeling language for mixed signal circuits, it provides both continuous-time and event-driven modeling semantics, and so is suitable for analog, digital, and mixed analog/digital circuits. It is particularly well suited for verification of very complex analog, mixed-signal and radio frequency integrated circuits.

## Code example[edit]

In VHDL-AMS, a design consists at a minimum of an *entity* which describes the interface and an *architecture* which contains the actual implementation; in addition, most designs import library modules. Some designs also contain multiple architectures and *configurations*.

A simple ideal diode in VHDL-AMS would look something like this:

```
-- (this is a VHDL comment)
library IEEE;
use IEEE.math_real.all;
use IEEE.electrical_systems.all;
-- this is the entity
entity DIODE is
generic (iss : current := 1.0e-14; -- Saturation current
af : real := 1.0; -- Flicker noise coefficient
kf : real := 0.0); -- Flicker noise exponent
port (terminal anode, cathode : electrical);
end entity DIODE;
architecture IDEAL of DIODE is
quantity v across i through anode to cathode;
constant vt : voltage := 0.0258; -- Thermal voltage at 300 K
begin
i == iss * (exp(v/vt) - 1.0);
end architecture IDEAL;
```

## VHDL-AMS Simulators[edit]

- ANSYS Simplorer
- Cadence Virtuoso AMS Designer
- Dolphin Integration SMASH
- Mentor Graphics Questa ADMS
- Mentor Graphics SystemVision
- Synopsys SaberRD

## References[edit]

**^**Christen E., Bakalar K.,"VHDL-AMS-a hardware description language for analog and mixed-signal applications",Circuits and Systems II: Analog and Digital Signal Processing, IEEE Transactions on [see also Circuits and Systems II: Express Briefs, IEEE Transactions on] Volume 46, Issue 10, Oct. 1999, pp. 1263 - 1272.

## See also[edit]

- Verilog-AMS, the Analog Mixed Signal derivative of the Verilog hardware description language
- VHDL
- IEEE 1076
- Electronic design automation
- Very-large-scale integration
- Modelica, a language for modeling physical systems