Designing a Circuit in PSPICE for Fast Bidirectional Switching

In summary, Justin is designing a circuit in PSPICE and needs a switch that can handle bidirectional current with a maximum of 80mA and an average of 30-40mA. The switching time should be fast, on the order of a microsecond. He is unsure of which type of switch to use and wants something that can be modeled in PSPICE and built on a breadboard. He considers using a relay but also wants low power dissipation, ideally below 10mW. The expert suggests using an analog switch made of complimentary CMOS transistors, but Justin needs a switch that can handle voltage swings of 40V. The expert suggests making a customized analog switch using high-voltage CMOS transistors.
  • #1
JustinH
9
0
Hi,
I'm designing a circuit in pspice and having some trouble with the switching. In my circuit in pspice I'm using an ideal voltage controlled switch model "S" and using a vpulse to control it. My current through the switch needs to be bidirectional, and maxing around 80mA with an average around 30-40mA. The switching time should be fast compared to a microsecond.

I'm not sure whether to use a BJT, a FET, an IGBT, a combination, or perhaps something else altogether.

I want something that I can model in pspice, and then be able to build on a breadboard.

Let me know if anything comes to mind.

Thanks,
Justin
 
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  • #2
Does PSPICE have a relay macro? Microcap 8 does. Is there anything about relays in the PSPICE Help menu?
 
  • #3
To be honest, finding part models in pspice is more than a hassle. Are you saying that I should use a relay? I forgot to mention, the switch that I use has to have low power dissipation at the currents I'm working with. Ideally the power dissipation should be below 10mW, not sure if this is feasible.
Thanks,
Justin
 
  • #4
Well, if you want fast switching times on the order of a microsecond, then I guess a relay would be a non-physical model to use in your simulation. You should use something more like what you will use in the real circuit. Look for an Analog Switch (which is made out of several complimentary CMOS transistors generally).
 
  • #5
Thanks for the help, analog switches look promising.
Justin
 
  • #6
Hmm, slight problem, I've been looking at analog switches, and they seem to fit the bill pretty well except the ones I've looked at have maximum voltage swings across the in and out terminals of around 5V. I need something that can handle voltage swings around 40V. I'll keep looking, but let me know if there's another device that will satisfy this requirement.
Thanks,
Justin
 
  • #7
One option would be to look at how an analog switch is typically constructed (with the complementary CMOS pass devices), and make your own with high-voltage CMOS transistors. I think that's basically how solid state relays are made, and they accommodate higher voltages.
 

1. How do I choose the components for my circuit in PSPICE for fast bidirectional switching?

To choose the components for your circuit, you need to understand the specifications and requirements of your design. These may include voltage and current ratings, switching speed, and frequency. You can then select components that meet these specifications, such as MOSFETs, diodes, and capacitors.

2. What are the key factors to consider when designing a circuit in PSPICE for fast bidirectional switching?

The key factors to consider include the maximum voltage and current ratings of the components, the switching speed, the power dissipation, and the overall efficiency of the circuit. Additionally, the layout and routing of the circuit should be optimized to minimize parasitic effects and ensure reliable operation.

3. How can I simulate the bidirectional switching behavior of my circuit in PSPICE?

PSPICE offers a wide range of simulation options, including transient analysis and frequency domain analysis, which can be used to simulate the bidirectional switching behavior of your circuit. You can also use the built-in models and libraries for components and devices to accurately model their behavior in the circuit.

4. What are some common challenges when designing a circuit in PSPICE for fast bidirectional switching?

Some common challenges include managing parasitic effects, such as stray capacitance and inductance, which can affect the performance of the circuit. Additionally, choosing the right components and properly sizing them to handle the required current and voltage can be challenging.

5. Are there any tips for optimizing the performance of a bidirectional switching circuit in PSPICE?

One tip is to carefully analyze the layout and routing of the circuit to minimize parasitic effects and improve signal integrity. Additionally, using high-quality components with low on-resistance and fast switching speeds can help improve the performance of the circuit. It is also important to perform thorough simulations and testing to fine-tune the circuit for optimal performance.

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