Abstract: A temperature-compensated reference voltage circuit includes a transistor having a positive temperature coefficient of current. A circuit for establishing a predetermined current in the positive-temperature-coefficient-of-current transistor is connected to that transistor. A predetermined resistance serially connects the positive-temperature-coefficient-of-current transistor with a transistor having negative temperature coefficient of base-to-emitter voltage. The temperature-compensated reference voltage is established between the transistors. The temperature-compensated reference voltage circuit is particularly useful in a supply voltage sense amplifier circuit for thermal printhead drive transistors or other load elements. The sense amplifier circuit includes a circuit for comparing the reference voltage and a supply voltage. An output is adapted to be connected to a load for receiving the supply voltage.
Abstract: A method and circuitry are disclosed for correcting bit errors introduced by random events in a data recirculating memory, such as a charge coupled memory device or a bubble memory. The bit errors, caused by random events such as by alpha particle bombardment or other causes, are corrected in circuitry that generates row and column parity bits corresponding to various segments of the information stored in the memory. Changes in the row and column parity bits uniquely define the location of failed bits circulating through the memory even though each failed bit has no fixed address, so that error detection circuitry thereafter may correct the error during the next or a subsequent bit recirculating cycle. The invention facilitates the use of very large memories, for example, on the order of one billion bits or more.