Discrete chopper switch

Hello,

I want to use some single chopper switches in my prototype PCB. However, when I searched in ADI product list, there are only chopper-stabilized amplifiers which usually consist of two chopper switches.

I just want to use one chopper switch in my design which seems like a mixer. So I was wondering if there is a product as I want. For instance, an IC integrates several chopper switches and several clock control signals.

Thanks and look forward to your reply.

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  • Hi Victor,

    It's weird, I've never seen anything like it. You can try to attach ZIP archive to the message.

  • Hi KirV,

    Thank you so much for your reply and patience. I am trying to edit it again.

    My basic idea is shown as above. I use a chopper, whose principle is shown in below (composed of four switches and they are controlled by a binary signal), to multiply the input analog signal with +1 or 1 according to the bit of PRBS (1 or 0). Then the signal goes through an active RC integrator.

    So I want to find a chopper device as above. However, when I search "chopper" in ADI product list, it only shows chopper-stabilized amplifer, which is not my target. I only want "four switches". Do you have any advice for the implementation of chopper?

    Furthermore, I also want some advice for the implementation of integrator. The only integrated integrator I found is TI's ACF2101 and it's a little bit old design. So could I use some devices from ADI such as the amplifer to achieve it? Are there switches used as reset switches in my design? Due to a huge amount of amplifer in ADI's product list, I seached something but they don't fit for me. If you know some example designs from datasheets, please let me know. It will be very appreciated!

    Victor

  • Hi Victor,

    Now I understand your idea. Those devices that I recommended above seem to be perfectly suitable for a chopper. I very much doubt that using four switches as an alternative will get you anything better.

    Why are ADI fully differential amplifiers not suitable for your application? What are your requirements for the circuit-supply voltage, permissible error, values of capacitors, speed? I may be able to advise you on suitable reset switches, but I need a little more information.

    Regards,

    Kirill

  • I am not familiar with integrated circuits that are called choppers or at least positioned as specially designed for this role. No wonder you couldn't find something like that with a search.

  • Hi KirV,

    Thank you so much for your generous help.

    I read carefully the datasheets of LTC1043 and 6943 you recommended. To my understanding, the control clock signal of these two chips are generated internally using pin16 (in 1043) and pin14 (in 6943). Their leakage currents are so low and CMRR are perfect.

    However, for my idea, I need a control signal, say PRBS in the above diagram, that is not a clock signal (say, duty cycle=50%). Its high and low levels are random. So it needs an external control signal. Do you know some devices suitable for my requirement? So far, my choice is a 2-bit bus exchange switch  https://www.onsemi.com/products/interfaces/analog-switches/7wb383. But it is actually used for digital signal. The leakage current is large. If there are analog swiches whose control signal can be given externally, they would be better.

    For the integrator, I have noticed you replied my another thread, so I will disscuss with you in there.

    Best regards,

    Victor