Copilot Simulator Tool

Flux Copilot includes a powerful simulator tool (currently in beta) that allows you to perform SPICE circuit simulations directly from the chat interface. This tool helps you quickly verify circuit behavior, troubleshoot design issues, and optimize component values without having to set up a separate simulation environment.

Overview

The simulator tool enables you to:

• Simulate electronic circuits using standard SPICE netlist syntax
• Verify circuit behavior and performance
• Check voltage and current at different points in a circuit
• Troubleshoot circuit design issues
• Test multiple circuit designs in one request
• Compare different circuit configurations

How to Use the Simulator Tool

To simulate circuits using Copilot, use the @simulator tool in your query:

@simulator Create a simple RC low-pass filter with R=1k and C=1uF and simulate its frequency response

​

@simulator Check the voltage ripple of this power supply circuit

When you use the @simulator tool, Copilot will:

1. Analyze your request to understand the circuit you want to simulate
2. Generate a SPICE netlist based on your description
3. Run the simulation using Flux's SPICE simulation service
4. Analyze the results and provide a meaningful interpretation
5. Handle any errors or convergence issues automatically

Plan and Execute Strategy

The simulator tool uses a sophisticated Plan and Execute strategy that:

• Identifies and corrects syntax errors in SPICE netlists
• Resolves convergence issues during simulation
• Tries alternative circuit configurations when initial attempts fail
• Analyzes results from multiple simulations
• Iteratively refines simulations based on previous results

This approach is particularly valuable for SPICE simulations, which often require multiple iterations to address syntax errors, convergence problems, or to optimize simulation parameters.

SPICE Netlist Format

The simulator tool works with standard SPICE netlist syntax. Here's a simple example:

* Simple RC circuit

V1 1 0 DC 1V

R1 1 2 1k

C1 2 0 1u

.tran 0.1u 10u

.print tran v(2)

.end

Important notes:

1. Always include a .print directive to specify which node voltages or branch currents to output
2. End the netlist with .end
3. Include appropriate analysis commands (e.g., .tran, .ac, .dc)

Example Use Cases

Here are some examples of how you can use the simulator tool:

Basic Circuit Verification

@simulator Verify if this voltage divider with R1=10k and R2=5k produces 3.3V from a 5V source

​

@simulator Check if this LED circuit with a 220 ohm resistor and 3.3V supply provides the correct current

Frequency Response Analysis

@simulator Analyze the frequency response of a low-pass filter with R=1k and C=0.1uF

​

@simulator Find the cutoff frequency of this LC bandpass filter

Transient Analysis

@simulator Simulate the step response of this RLC circuit

​

@simulator Check the ripple voltage in this power supply circuit

Comparing Circuit Designs

@simulator Compare the gain of these two op-amp configurations

​

@simulator Which RC filter design has a better frequency response?

Tips for Effective Simulations

To get the most out of the simulator tool:

1. Be specific about component values - Specify resistance, capacitance, and other component values with appropriate units (e.g., 1k, 10uF).
2. Describe the circuit topology - Clearly explain how components are connected or provide a detailed netlist if possible.
3. Specify the analysis type - Mention whether you want a transient, AC, or DC analysis.
4. Identify points of interest - Specify which node voltages or branch currents you're interested in observing.
5. Break down complex circuits - For very complex circuits, consider simulating smaller subsections first.

Common Issues and Solutions

The simulator tool can automatically handle several common simulation issues:

Syntax Errors

If your netlist has syntax errors, the tool will:

1. Identify the specific error in the netlist
2. Suggest a corrected version of the netlist
3. Retry the simulation with the corrected netlist

Convergence Issues

For convergence problems, the tool will:

1. Identify potential causes of convergence failure
2. Add appropriate .OPTIONS statements to help with convergence
3. Adjust component values if necessary
4. Try alternative simulation parameters

Time Step Issues

If time step errors occur, the tool will:

1. Adjust .TRAN parameters to use smaller time steps
2. Add .OPTIONS RELTOL or .OPTIONS ABSTOL statements
3. Retry the simulation with the adjusted parameters

Limitations

While the simulator tool is powerful, it has some limitations to be aware of:

• Very complex circuits may exceed simulation capabilities
• Certain specialized SPICE models may not be available
• Exotic or non-standard SPICE syntax might not be supported
• Simulations are limited to basic electrical behavior and don't include thermal or mechanical effects
• Large simulations may take longer to process

Related Features

The simulator tool works well with other Copilot capabilities:

• Copilot Help Tool - Search Flux documentation for guidance
• Copilot File Tool - Extract information from datasheets
• Copilot Calculator Tool - Perform engineering calculations
• Copilot Code Tool - Generate Python scripts for more complex analyses
• Getting Started With Copilot - Learn the basics of using Copilot