Autonomous Ferroelectric Memory

Radiant has developed a unique memory circuit utilizing the remanent hysteresis of ferroelectric capacitors.  The circuit is a single memory bit using a single ferroelectric capacitor that operates autonomously!  The term autonomous in this case means that the memory needs no microprocessor, no clocks, not control lines, or any kind of controller to execute its primary function:  retain its assigned value.  In its simplest form, which is also the simplest definition of a memory bit, the autonomous memory has only three connections:  Power, Ground, and Output.  It can be represented by the symbol below:

 

The operation of this memory is very simple:   1.  While Power is applied to the circuit, drag the Output to the desired state Hi or Lo and it remains.     2.  If Power is removed, the Output returns to its last state when Power is restored.

 

That is it!  It would seem that there is no more simpler memory operation but there is.  This memory can be written while power is off and then read when power is restored.  Below is a link to an application note explaining the circuit theory for this memory bit and describing an array of circuit configurations that will work.  In fact, the autonomous ferroelectric memory can be fabricated in discrete circuits or in integrated circuits using any existing IC manufacturing technology.  

 

A simple autonomous memory circuit design is provided at the following link:

A much more invovled explanation of circuit theory is in the following application note:

A single bit of memory may seem limited until you realized that a light switch is a single memory bit.  Light switches are everywhere!  Autonomous bits may be ganged into registers or counters to create sensors with amazing properties.  The links below give just a few ideas on this subject.

The two products below are intended to provide educational and experimental platforms to explore autonomous memory. 

 

 

 

The Single Bit Memory Demonstration board is an open-source circuit board containing a complete autonomous memory bit including a power conditioner, memory latch, and output LED indicators.  The memory bit is manually operated through push button switches. The The AB or Type AL ferroelectric capacitor that stores the memory resides on a removable daughter board.  The daughter board is symmetrical so it may be inserted into its socket facing in either direction. 

 

This product is intended as a training tool for electrical engineers to learn the inner workings of the autonomous ferroelectric memory so they may design their own memory bits.  Most of the components on the board are surface mount but the five critical components that define the successful storage and recall of the stored memory are discrete devices that may be removed and replaced. 

All memory circuits are analog circuits, not digital circuits. To this end, the demonstration board has four test points suitable for connecting oscilloscope probes to capture the dynamics of the voltages in the circuit during write and read operations. 

 

The link below contains instructions for operating the demonstration board. 

Refer to the application note for the circuit theory.

The autonomous memory board is a small PCB implementing an autonomous ferroelectric memory circuit for use in experimental circuits.  It has a Type AB capacitor with a 1 year lifetime or a Type AL capacitor with a 10 year lifetime.  The board includes two analog switches that may be wired to the input of the non-volatile latch or may be controlled by the output of the non-volatile latch to implement any of the logic or control functions described in the application note.  The analog switches allow the board to control motors, relays, lights, or actuators according to the state of the memory. The board is capable of operating at up to 40 volts supply.  It has ten pins:

A datasheet and application note for this product will be available August 30, 2011.