Please help me find a fast, dual supply SPDT analog switch

My use case is to create a variable amplitude one-shot pulse (with a width of 1-2us) using the SPDT. A single pulse is used as a trigger to the switch. I have been using ADG619 till now but its very slow (80-150ns rise/fall time due to high Ton and Toff time of the switch) and hence introduces big rise and fall edges to my 1-2us (single) pulse. The pulse height would be a maximum (can be less than that) of 3Vp-p and the amplitude would range between ±3V. So I need a dual supply switch. I would really prefer it if the rise and fall time reduces to around 10-20ns.

I did some searching and I couldn't find many things except AD8170 but I am not sure if it is an analog switch or just a digital mux (also couldn't verify it since the simulation model doesn't work). If you have any recommendations, please let me know.

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    •  Analog Employees 
    on Jan 19, 2021 4:26 AM

    Hi paulplusx,

    Can you share your schematic so we can understand and recommend the best fit switch for your application.

    Thanks,

    May

  • What I am trying to is generate an arbitrary one-shot pulse (variable width and variable amplitude). The amplitude is set by the DAC output which is then fed into one input of switch (ADG619). The second input of the switch is ground. Then I use a pulse generator (LTC6993-1) to trigger the switch between ground, DAC output, and back to the ground, which creates a pulse of the width approximately the same as the pulse trigger. The problem with ADG619 is the t_on and t_off times are not good as mentioned in the post, which creates a large rise and fall times for the output pulse. So I need a faster switch for having a short rise and fall time. If you still need a schematic I can provide it to you.

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  • What I am trying to is generate an arbitrary one-shot pulse (variable width and variable amplitude). The amplitude is set by the DAC output which is then fed into one input of switch (ADG619). The second input of the switch is ground. Then I use a pulse generator (LTC6993-1) to trigger the switch between ground, DAC output, and back to the ground, which creates a pulse of the width approximately the same as the pulse trigger. The problem with ADG619 is the t_on and t_off times are not good as mentioned in the post, which creates a large rise and fall times for the output pulse. So I need a faster switch for having a short rise and fall time. If you still need a schematic I can provide it to you.

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    •  Analog Employees 
    on Jan 22, 2021 4:27 AM in reply to paulplusx

    Hi paulplusx,

    Have you tried using the Parametric Search Engine? Go to analog.com -> Products -> Switches & Multiplexers.

    You may use this online tool and filter the parameters required for your application. 

    I used this tool and filtered device configuration (2:1), Vspan Dual (15max), and enabled timing parameters for your preferred ton and toff. It will generate the available switches:

    • ADG6xx (25ns to 100ns timing)
    • ADG78x (7ns to 19ns)
    • ADG73x (7ns to 19ns)

    From here you can choose which switch is best fit for your requirement.

    Let me know if this helps.

    Regards,

    May