Inquiry: Dynamic Envelope Shaping of a 350MHz Carrier using AD8367 V_gain Control

Here is a snippet from the datasheet that speaks to the bandwidth of the GAIN input pin.

“The AD8367 can be used as a means of modulating the signal level. Keep in mind, however, that the gain is a nonlinear (exponential) function of VGAIN; thus, it is not suitable for normal amplitude-modulation functions. The small signal bandwidth of the gain interface is ~5 MHz, and the slew rate is of the order of ±500 dB/μs. During gain slewing from close to minimum to maximum gain (or vice versa), the internal interpolation processes in an X-AMP-based VGA rapidly scan the full range of gain values. The gain and offset ripple associated with this process can cause transient disturbances in the output. Therefore, it is inadvisable to use high amplitude pulse drives with rise and fall times below 200 ns”

So bandwidth-wise, you should be good to go. But remember that the gain control is linear in dB, not linear in V/V. So your are not going to have  a 1:1 linear relationship between your modulating signal (the signal you apply to the GAIN pin) and the resulting  output envelope of the signal. If this is an issue, you may want to consider using an analog multiplier circuit such as ADL5391.  

Here is a snippet from the datasheet that speaks to the bandwidth of the GAIN input pin.

“The AD8367 can be used as a means of modulating the signal level. Keep in mind, however, that the gain is a nonlinear (exponential) function of VGAIN; thus, it is not suitable for normal amplitude-modulation functions. The small signal bandwidth of the gain interface is ~5 MHz, and the slew rate is of the order of ±500 dB/μs. During gain slewing from close to minimum to maximum gain (or vice versa), the internal interpolation processes in an X-AMP-based VGA rapidly scan the full range of gain values. The gain and offset ripple associated with this process can cause transient disturbances in the output. Therefore, it is inadvisable to use high amplitude pulse drives with rise and fall times below 200 ns”

So bandwidth-wise, you should be good to go. But remember that the gain control is linear in dB, not linear in V/V. So your are not going to have  a 1:1 linear relationship between your modulating signal (the signal you apply to the GAIN pin) and the resulting  output envelope of the signal. If this is an issue, you may want to consider using an analog multiplier circuit such as ADL5391.