fxhfzy
Newbie level 6
Help for pushpull amp
I am designing a 200W,IMD3<-40dBc amp for 57-63MHz operation with freescale transistor MRF6VP2600.
I finished the circuit building, found a stable bias at Id=2.3A,Gain=24dB(f=60MHz) and measured the VSWR with network analyze(Pin=20dBm),vswr1=1.4,vswr2=7.2 @ f=60MHz.
Then I began to increase the input power(f=60MHz),I increased Pin 2dBm everytime.Gain remained 24dB until Pout=37dBm,it droped to 4dB and couldn't recover.
I have taken the transistor down,it seems to be secondary breakdown.Is there anyone could tell me why the transistor breakdown and what shall I do next?
The schematic circuit is as follows:
The amp picture is as follows:
I have upload the datasheet and ADS simulation files.[/img][/b]
I am designing a 200W,IMD3<-40dBc amp for 57-63MHz operation with freescale transistor MRF6VP2600.
I finished the circuit building, found a stable bias at Id=2.3A,Gain=24dB(f=60MHz) and measured the VSWR with network analyze(Pin=20dBm),vswr1=1.4,vswr2=7.2 @ f=60MHz.
Then I began to increase the input power(f=60MHz),I increased Pin 2dBm everytime.Gain remained 24dB until Pout=37dBm,it droped to 4dB and couldn't recover.
I have taken the transistor down,it seems to be secondary breakdown.Is there anyone could tell me why the transistor breakdown and what shall I do next?
The schematic circuit is as follows:
The amp picture is as follows:
I have upload the datasheet and ADS simulation files.[/img][/b]
