I designed an input, output AC Coupled amplifier by AD8009. output ac couple circuit has a 47u capacitor.
are there any issues for ad8009 to working with this cap value as an output ac coupling?
Hi,Can you show your schematic, 47uF seems too large. What will be the next stage after the AD8009? What is your load?Regards,Goz
Thank you for the reply.
the load that I said before is input of AD8302 and its input ac coupled capacitor.
yes 47u seems too large. I plan to use AD8302 in a wide frequency range from 20Hz to 50Mhz.
I plane to use AD8009 or AD8007 as last stage buffer of my analog front end circuit before AD8302.
before AD8009 I have a resistive Attenuator, one AD4817 as a High Speed FET input buffer and a AD8337 as a VGA and then a AD8009/8007 as a buffer between the input circuits and AD8302.
also my other discussion about AD8067+AD8009 vs AD4817+AD8009 composite amplifier is related to this circuits.
after these AD8009 buffer, I have another signal path that need to amplify input by 80dB gain and I plan to do it by two composite amp that each has 40dB gain and multiplexed 0dB, 40dB and 80dB by a AD8174 with 0dB gain.
these high gain stages must be ac coupled in range 20Hz to 50Mhz.
so it is.
I highly appreciated to have your kindly recommendation about the circuit.
PS: the schematic is something like this
if im going to put a series resistor with ad8009 output, does it solve the problem due to large capacitive load or not? if it does, how can i calculate the proper value of series resistor based on value of ac decoupling capacitor?
according to datasheet, large cap load may be cause non-stability or oscillation in high frequencies, so what is this range? in 1 MHz or 2 MHz this non-stability could be accrued in 1 or 2 MHz till 30 MHz or amplifier may be oscillate in frequencies above this numbers?
Dear Gauzz, any suggestions!!?