Featuring very low power consumption, 675 nA is the total current consumption for this amplifier circuit. The output voltage swing is 300 mVpp with a 20 kΩ load. This very low power design is made possible by high gain low power operational amplifier CA3078.
CA3037 is marked as obsolete product by Intersil, but they suggest ICL7611,ICL7612, CA5420A, CA3140, or CA3160 for the possible substitution. Check each of their datasheet to make sure you pick up the most suitable part for CA3037 replacement. [Circuit’s schematic diagram source: seekic.com]