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I used two mosfets to control current passing through resistance 5ohm, shown in the circuit of the attached file. The simulation results show that the mosfet switching frequency higher than 10KHz controls the level of the current with small perturbation. I set up such circuit on the bread board. The mean value of current increases as the frequency increases up to 2kHz and level of perturbation decreases with increase of frequency. However, I observed a strange response for frequency greater than 2 KHz. The current signal becomes as a rectangle pulse (with zero value as minimum and a maximum value with some small perturbation) for frequency greater than 2KHz. The attached file shows the results for frequency of 10kHz. Such experimental results show that the mosfet periodically turns off during approximately 1 second in spite of switching signal applied on the mosfets. How can I resolve such problem for frequency more than 2KHz? enter image description here

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    \$\begingroup\$ The scales are impossible to read and the MOSFET signal noise looks really bad. What were you expecting to see (in all circumstances of frequency) and have you considered the effects brought about by the output inductor, L1? Are your pulse drive waveforms synchronized? \$\endgroup\$
    – Andy aka
    Commented Jun 29, 2021 at 11:35
  • \$\begingroup\$ Dear Andy aka. The vertical axis is the output for current sensor with 10-bit ADC (-30A at 0, zero current at 512 and 30A at 1024). Horizontal axis is the number of time frame recorded at each 1ms. The driving signal of Q1-mosfet is the negative signal for driving Q4-mosfet. I am trying to design a circuit with a stable current at the output of inductor. One solution is to switch the mosfet in high frequency. Please let me have your suggestions to modify the current control circuit. Best regards \$\endgroup\$
    – Mohammad Tahaye Abadi
    Commented Jun 29, 2021 at 13:39
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    \$\begingroup\$ If you drive the MOSFET Q1 as shown in the schematic, the gate signals of Q1 may get chopped off due to the fact that the output impedance of the pre-driver (5k) and the Ciss of Q1 (1.6nF) form an RC filter with fc=19.9kHz. Plus, driving the hi-side MOSFET may get even problematic in your circuit. Maybe you should use a PMOS instead. \$\endgroup\$
    – Rohat Kılıç
    Commented Jun 29, 2021 at 13:49

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