I was using MCP6004 from Microchip and tried to replace it with LT1679 . Problem is I see the signal is noisy after replacing the MCP amplifier with the new LT selection. Is there any better alternative (Single and Quad amplifiers if possible)? Thanks
What is your source impedance in this configuration where you replaced MCP6004 with LT1679 and got higher noise reading?
If your input impedance is "high", you'd want to choose a device which has low current noise density. LT1679 input current noise density is higher than MCP6004. It is also a 20MHz part vs. 1MHz for MCP6004. So, it could be that you need to reduce your closed loop bandwidth to reduce excess noise beyond your freq range of interest.
Here are some suggestions:
Quad: LTC6082, LTC6088, or AD8648.
Single: AD8615, or AD8605.