Homebrew RF Levelling Amplifier

[David Hess]

Oh! Yes, a good example is the circuit of the Tektronix SG503 leveled signal generator.

Regading to the extraing diode, I think it is used in case of Vrf is too high (to speed up the opamp output voltage??).

It is impossible to tell without knowing the details of the operational amplifier  The RF will get rectified by the input differential pair and the diode.  It is not really a configuration to be relied on.

[e.sotillet]

Hi

I sorry for not give the entire details of the circuit. The V_RF is a DC voltage proportional to the output power of the amplifier, it comes from an AD8317. V_REF comes from a voltaje divider to stablish the setpoint. My doubt was about the function of the diode, I made a couple of simulations and didnt find differences between the circuit with the diode and without it. I dont know if I'm missing something.

Best regards