A Solid -State Operational Amplifier of High Stability

also invaluable for increasing the sensitivity of voltmeters and recorders, or isolating them from the signal source. For all of these appli cations, though, the amplifier must have a high degree of gain stability and very low in trinsic voltageor current-offset to permit the accurate observation of the desired signal. A new dc amplifier has been designed which achieves greater reliability and accuracy than previously available in a solid state device of this type. A maximum drift level of 1 micro volt per week at constant temperature and a temperature coefficient of but one-half micro volt per °C with a 100 kilohm summing point impedance constitute an order of magnitude improvement over previous all-solid-state dc amplifiers. The amplifier is designed with plug-in modules that permit a wide variety of applications. It has a gain stability of ±.01% per week, is extremely reliable, and is unaf fected by mounting position or external vibra tion, as no mechanical choppers or vacuum tubes are used.