Analog Memory Devices Employing Pe-Fe Interactions for Adaptive Control Voltage Modules

Abstract

Adaptive ferroelectric devices utilizing piezoelectric (PE)-ferroelectric (FE) interact~ons ate reviewed. These devices are typ~cally composed of two ceramic FE capacltors mechanically bonded together. When an input voltage 1s applled to one capacitor. it vibrates due to its PE properties. The vibrations are coupled to the output capacitor where a PE voltage is developed. Because of thc PE-FE interaction the PE coefficients of the capacitors depend on their state of FE polarization. Thus, the output voltage of the device can be ‘set’ to different values by the application of a polarizing voltage adapt pulse to either of its capacitors. Electronic control systems requiring analog memory for ‘setting’ a variable or function to a desired level have generally been limited to ones employing mechanical memory devices. Solid-state systems are possible using adaptive devices. One such system is described which supplies a ‘settable’ control voltage in the range 0 to + IO Vdc that can be remembered accurately for periods of time measured in years. yet can be changed quickly (milliseconds) or slowly (dekaseconds) merely by applying a polarizing voltage adapt pulse. Positive or negative pulses reduce or increase the control voltage setting, respectively. The system can be used for analog control of electronic functions provided appropriate automatic gain control circuits are employed.