Problem about power MOSFET SWITCH

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Hi everybody
I met a problem I dont know how to solve it. In this circuit. Q3 and Q7 worked as a switch.
But when the input voltage reaches to 20Mhz. The input signal will be found at the gate foot of Q3.
Whether I can change this circuit to improvement its work at this frequency. Capacitor between gate and drain make this problem I think. I'm noob. I feel confused about this problem . Please give me some advice~:?::?::?:
 

For the MOSFET Q3, from datasheet it looks like it cannot function at switching frequencies of more than 5.55MHz with typical values. Check the Switching Characteristics in its datasheet.
 

Hi ravindragudi :
Thanks for your reply. How can you get the frequency of 5.55MHz ?I'm noob . Maybe I made you misunderstand my problem . The switch MOSFET period which is the period of control signal at Q3's 1 foot is about 100 us. But the input signal from Q3's 2 foot to Q3's 3 foot is 22MHz. So I don't think my problem thanks to the switching characteristics.
 

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