ADA4500 has a low voltage noise density of 14.5 nV/√Hz. Placing a 1KΩ resistor
with thermal noise of 4 nV/√Hz at the input of the amplifier increases total
input referred noise to 15 nV/√Hz; placing 4kΩ resistor at the input increases
the total noise to 21.6 nV//√Hz . It is important to use low value resistors
around a low-noise amplifier.