Hello!
I was wondering if there was any additional information about the noise density of the LMP7704 at lower frequencies. I'm interested in using this amplifier in a lower bandwidth application where the 1/f noise could become an issue. I was wondering if there was a graph that could be provided similar to the input voltage noise density vs frequency? If a graph is not available, is there any information on the current noise density at frequencies lower than 100kHz
Thanks,
Billy
You may simulate the input current and input noise spectral density by using our macro-model - see below. As Michael said, the current noise in linear CMOS and JFET input op amps has no 1/f component and it value is a function of the input bias current, Inoise = (2*q*IB)^0.5, so for IB below 1pA Inoise is below 1fA/rt-Hz. At higher frequncy IB increases due to charging of input capacitance - this results in artifact of Inoise increasing above 1kHz, which then gets attenuated above 2.5MHz by bandwidth roll-off - see below.
