A simple, reliable, and highly stable AC voltage amplifier for calibration purposes

The present commercially available ac amplifiers for testing and calibration purposes generally use electronic devices operating at high power levels. These amplifiers are rather prone to instabilities and usually produce a noticeable amount of heat, which must be vented to the ambient. The design of a simple and inexpensive precision ac voltage amplifier is presented, in which all internal electronic devices operate at low power and consequently produce less heat. The measured gain stabilities (amplitude and phase) of the amplifier were around ±1 μV/V and ±1 μrad, respectively, over 30 min.