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  • Level shifter

    Attached is a level shifter circuit. This works OK for a pulse width of 5us and more, but there is some propagation delay. The switching speed is also affected by the output voltage, in this case the battery charge level.

    Using HF transistors makes the switching faster for pulses of 1us.

    I am looking for a better solution, less propagation delay, better accuracy, faster switching.

    Any suggestions?

    Tinkerer
    Attached Files

  • #2
    Keep the PNP linear.

    Comment


    • #3
      Yes, a bit of emitter degeneration does the trick. Delays happen when transistor goes elsewhere from saturation. You may observe it as spikes in base current. Degeneration helps.

      I made some minor differences to your schematic, not to ruin your concept. Enjoy
      Attached Files

      Comment


      • #4
        What about this one?

        (Who dares to optimize it further?)
        Aziz

        PS: The output doesn't need a mosfet driver! It has the driver built-in.
        Cheers
        Attached Files

        Comment


        • #5
          I played a bit with ECL Schmitt trigger and it is now just some 20ns slower that yours, yet there are no nasty transients in transitions, and power consumption is just right
          Attached Files

          Comment


          • #6
            Originally posted by Davor View Post
            I played a bit with ECL Schmitt trigger and it is now just some 20ns slower that yours, yet there are no nasty transients in transitions, and power consumption is just right
            Good one! I like it.

            Tinkerer should be happy now.

            Aziz

            Comment


            • #7
              Slight modification (other transistor) improves the level shifter + mosfet-driver + power consumption:

              Aziz

              Another proposal?
              Attached Files

              Comment


              • #8
                Maşallah

                Comment


                • #9
                  Hey people, did anyone here actually included MOSFET gate as a load in these circuits?

                  Comment


                  • #10
                    Originally posted by Tepco View Post
                    Hey people, did anyone here actually included MOSFET gate as a load in these circuits?
                    Here is the complete TX schematic. I have not changed the level shifter yet, but will probably go with Davor's ELC, since I already have the mosfet driver. The mosfet driver needs about 6A peak current.

                    many thanks to Carl, Aziz and Davor for the great help. A genius is a genius. What is the plural of genius?

                    Tinkerer
                    Attached Files

                    Comment


                    • #11
                      This looks excellent, UC3710 is not mentioned, so i assumed circuit should drive FET directly. Never mind, i will add one more, completely unrelated post about ECL and it's speed, maybe interesting to someone.

                      Comment


                      • #12
                        Originally posted by Tepco View Post
                        Hey people, did anyone here actually included MOSFET gate as a load in these circuits?
                        See below.

                        No problem with the right complementary pair transistor stage (see below). Generally, a mosfet based mosfet-driver (complete IC) is more convenient of course (low power, low impedance, fast switching, high load drive capability).

                        So use the ECL driver above and feed it to the mosfet-driver IC. I personally like the ECL driver more than my proposal.

                        Cheers,
                        Aziz

                        PS: The 2N2907 seems to be slower than the BC557-B.
                        Attached Files

                        Comment


                        • #13
                          More Drive Capability with BC368/BC369

                          Hi all,

                          if you need more drive capability, use the complementary transistor pair BC368/BC369. It delivers enough power for our purpose. Notice, I have a 20 nF load capacitance this time.

                          Cheers,
                          Aziz
                          Attached Files

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