hi, i have a question about AGC loop (using ADL5330 and AD8318)
i'm making the circuit about AGC, you can see the figure1
i want the constant power about -30dBm
so i was changed input power level of VGA(ADL5330) when i fixed setpoint voltage
but power was not fixed
i think in situation of fixing setpoint voltage, even though vga input power level is change, vga out power have to be fixed, is it right?
but it's changable
the VGA(*adl5330) has the gain range of -30 ~ 16 dBm at 2200MHz
and i'm using the 20 dB coupler. so i need detector range of -50~04 dBm, so i select AD8318
but important thing is that the loop is not fixed (for changing the input level & fixing setpoint voltage)
so how can i get this condition
No.1 ) constant power level of -30dBm,
No.2 ) VGA input power level -40~0 dBm (it's changeable)(tell me what range needed)
here's my question
No.1) What's the problem about my circuit?
No.2) what setpoint voltage needed when i get -30dBm of VGA power out level?
No.3) what range of VGA input level needed? how can i decide it?
No.4) R divider value (412/1Kohm) is nesessary?
No.5) i need more specific answer, so tell me more about this solution
please reply quickly
i'm waiting for your answer,
Try setting VSET to 1.8 V and sweep the power level that is going into the ADL5330. ( this assumes the coupling value is -20dB) The voltage divider placed between the VOUT pin of the AD8318 and the VGAIN pin of the ADL5330 is required so the voltage from the AD8318 will not exceed the maximum voltage rating of the VGAIN pin of the ADL5330. in controller mode, the VOUT can swing to the rail. (5V)