• I need 2 kHz -10/40 V square wave duty <1 % pulse to drive 50 ohm load.
  • I have a working 0-40 V solution: PWM by MCU driving a N-MOSFET low side switch off a 40 V DC rail.


simulate this circuit – Schematic created using CircuitLab


  • Is it possible to somewhat shift the voltage to negative after MOSFET output (low side is tricky, no common ground)?
  • If not, what is the most practical way to produce such pulse?
  • \$\begingroup\$ Transformer if you can find a suitable one. \$\endgroup\$
    – DKNguyen
    Commented Feb 3, 2021 at 14:45
  • 1
    \$\begingroup\$ If you need low to be -10 volts irrespective of changes in duty cycle then you need a negative rail or circa 12 volts. Create one or make one or redefine 0 volts as -10 volts. \$\endgroup\$
    – Andy aka
    Commented Feb 3, 2021 at 15:16
  • \$\begingroup\$ If you don't have a -10 V supply, you can use a zener clamp with a DC restorer starting with a 50V supply. using very low ESR RdsOn parts tinyurl.com/y2rvywy6 \$\endgroup\$ Commented Feb 3, 2021 at 23:25
  • \$\begingroup\$ @Andyaka Could you please show me how to use the negative rail ? If I insert negative rail to high side, L will be short. If I insert negative to low side, MCU will be burnt. \$\endgroup\$
    – 7E10FC9A
    Commented Feb 6, 2021 at 11:51

1 Answer 1


The best way to do this is by using a differentiator(op-amp circuit).This website provides the basics.


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