Nondestructive Readout Operation Research Articles

High density and long retention non-destructive readout FeRAM using a linked cell architecture

A 64 Kbit non-destructive readout (NDRO) ferroelectric random access memory (FeRAM) using a 0.6-μm technology is described. The NDRO FeRAM uses a novel linked cell architecture, which minimizes the circuit overhead accepted in Flash memories. This test device has shown 10-year retention and unlimited read operation. An 120-ns NDRO operation is performed at a read voltage of 2.2V. Circuit techniques used in the NDRO FeRAM include: (1) direct programming of ferroelectric capacitors, (2) automatic restoring of read data, and (3) data storing under zero bias conditions. The unique linked cell architecture allows for scaling a cell size down to 6F 2, where F is the minimum feature size available.

ＣＭＤ撮像素子を用いた広ダイナミックレンジ撮像方式

Charge-modulation-device (CMD) image sensors feature non-destructive readout and high-speed operation. By using the source-reset method in the CMD reset operations, it is possible to control the reset of the pixel-accumulated charge from outside the sensor. Making use of these features, we propose a subject-adaptive-type wide-dynamic-range imaging system that increases the dynamic range of the CMD by activating the electronic shutter only for areas having strong incident light. This prevents the sensor from becoming saturated. The advantage of this system is that there is no need to modify the conventional CMD structure to increase the dynamic range-only a simple circuit need be added outside the sensor. Experiment on this system was performed using such CMDs as line and two-dimensional sensors, and the dynamic range was increased twice as much.

A vortex transitional memory cell for 1-Mbit/cm/sup 2/ density Josephson RAMs

We developed an 8.5 /spl mu/m/spl times/11.5 /spl mu/m vortex transitional (VT) memory cell. The memory cell is the smallest Josephson memory cell ever reported. The cell was fabricated by electron cyclotron resonance plasma etching and bias-sputtering planarization. This is also the first Josephson circuit fabricated with sub-micron minimum feature size. Proper nondestructive read-out operation was verified even after half-selected conditions. An operating margin of /spl plusmn/14% was obtained for control currents I/sub X/ and I/sub Y/. These results are promising for developing a 1-Mbit/cm/sup 2/ density Josephson RAM.

Pt/PZT/n-SrTiO3 Ferroelectric Memory Diode

We fabricated a new nonvolatile ferroelectric memory, which consists of vertical metal-ferroelectric- semiconductor diodes. Our diode has a simpler structure than an Ferroelectric Random Access Memory (FRAM) cell, and operates at a lower voltage than Metal Ferroelectric Semiconductor Field Effect Transistors (MFS-FETs) or conventional flash memories. We demonstrated the memory operation using a Pt/PZT/n- SrTiO3 diode in this work. We deposited (001)-oriented PZT on (100) 0.5 wt% Nb doped n-type SrTiO3 substrate using a laser ablation technique. The diodes had a hysteresis loop in their capacitance-voltage characteristics due to ferroelectric polarization in the PZT layer. Their current-voltage curves were Schottky-diode-like and also had a hysteresis loop due to the ferroelectric remanent polarization. We confirmed correct nonvolatile and nondestructive memory readout operation. The write voltages were -5 V to write a logic “0” and above 2.5 V to write a logic “1”. The read voltage was 0.8 V.

水平３ライン同時出力を備えた増幅型固体撮像素子ＡＭＩ

An image sensor for image processing has been developed. A 1/4-inch 250, 000 pixel amplified MOS imager has been equipped with three independent outputs. The amplified MOS imagers nondestructive read-out operation and three lines of memory built in the sensor make it possible to output the signals of three independent lines simultaneously. By applying this function, a vertical DTL circuit and an FPN suppression of 10.8 dB are realized without an external memory.

Nondestructive readout mode static induction transistor (SIT) photo sensors

The nondestructive readout (NDRO) performance of two static induction transistor (SIT) photosensors, a 40*40 pixel area array and a 140-b linear array, is examined. NDRO operation in the SIT sensors is demonstrated by imaging with the area array and by examining the output waveform of the linear array. The charge lost per NDRO cycle in the linear array was 0.014% near the saturation signal level, and no charge loss could be detected at the >

Single flux-quantum Josephson memory cell using a new threshold characteristic

A new single flux-quantum Josephson memory cell in which nondestructive readout (NDRO) operations can be realized with a simple circuit configuration is proposed. The memory cell utilizes a new type of threshold characteristics in an equivalent asymmetric dc superconducting quantum interference device (SQUID) consisting of a three-junction SQUID gate and a single junction. NDRO operation has been successfully demonstrated in an experimental memory circuit.

An Improved Josephson Interferometer Memory Cell for Nondestructive Read-Out

An improved single flux-quantum Josephson interferometer memory cell which brought stable nondestructive read-out (NDRO) operation was proposed. The cell was constructed with an end-fed asymmetric two-junction interferometer, in which the bit operating current level could be set far above the critical point for stable NDRO operation. Damping condition for proper memory operation was studied by computer simulation. The NDRO operation was experimentally obtained for the McCumber damping parameter βc of 300–400.

Charge-injection imaging: Operating techniques and performances characteristics

The charge-injection device (CID) imaging technique employs intracell transfer and injection to sense photon-generated charge at each sensing site. Sites are addressed by an X-Y coincident-voltage technique that is not restricted to standard scanning. Free-format (random) site selection is possible. An epitaxial structure provides a buried collector to prevent recollection of the injected charge. In sequential injection, the charge is injected into the substrate and the resulting displacement current sensed. In parallel injection, the functions of signal charge detection and injection have been separated. The injection operation is used to reset (empty) the charge storage capacitors after line readout has been completed. Nondestructive readout (NDRO) is possible by deferring the injection operation. Low-loss NDRO operation has been achieved using a cooled imager. High sensitivity, low dark current, high modulation transfer function (MTF), and low blooming are some additional advantages of sensing signal charge levels within the array. Compared to the charge-coupled device (CCD), the CID approach results in a relatively high output capacitance; however, this is not considered to be a performance-limiting factor for most imaging applications.

Charge injection imaging: operating techniques and performances characteristics

The charge-injection device (CID) imaging technique employs intracell transfer and injection to sense photon-generated charge at each sensing site. Sites are addressed by an X-Y coincident-voltage technique that is not restricted to standard scanning. Free-format (random) site selection is possible. An epitaxial structure provides a buried collector to prevent recollection of the injected charge. In sequential injection, the charge is injected into the substrate and the resulting displacement current sensed. In parallel injection, the functions of signal charge detection and injection have been separated. The injection operation is used to reset (empty) the charge storage capacitors after line readout has been completed. Nondestructive readout (NDRO) is possible by deferring the injection operation. Low-loss NDRO operation has been achieved using a cooled imager.

Applications of plated wire to the military and space environments

Plated wire is steadily emerging as the preferred storage element for military and space memory applications. Not only are cost and performance improvements extending the regions of application, but reliability conscious military and space programs are adopting this type of memory. This is evidenced by the advent of hardened plated-wire memories for Poseidon and Minuteman missile programs. A prime reason for the attractiveness of plated wire for these applications is its ideal property of true nondestructive readout (NDRO) operation, in which the stored word is retained in the storage medium during all portions of the read cycle. This is made possible by the production of a uniaxial anisotropic closed-flux magnetic film during the plating process.

Nondestructive readout in nonplanar magnetic films

In memory applications the desire to increase speed by eliminating the rewrite cycle has intensified the interest in nondestructive readout (NDRO) operation. This paper is concerned with grooved structures considering the effect of grooves parallel to the easy axis in relaxing the limitations imposed by skew and angular dispersion upon the allowable word field. The reasons for the improved NDRO threshold are discussed on the basis of a quasi-static model assuming uniform magnetizations in the thick and in the thin regions of the film with a springlike exchange coupling. M-H loops and NDRO thresholds are calculated and compared with experimental evidence. Landau-Lifshitz equation is applied to the same two-magnetizations model to calculate voltage waveforms of the output signal. Calculated peaks are shown to be larger than for an ungrooved film operating under NDRO limitations. The results of inductive pulse measurements indicate a similar improvement.

Speed capabilities of ferrite cores in NDRO operation

Nondestructive readout (NDRO) of ferrite cores with switch times of 4 ns at 80-MHz repetition rates has been attained by permeability sensing of the difference signal between a core at its remanent state (low permeability) and a core at its partially switched (maximum permeability) state. Limited duration interrogate pulses exceeding core thresholds were used. A variety of coercivities, materials, and sizes were investigated. Higher permeability differences were obtained with low-coercivity cores than with high-coercivity cores. Signals of 10 mV were obtained using 21-mil cores 6.7 mils high. Although some cores yield higher difference signals, they are not well suited for memory applications because of their size and drive requirements. Variations in remanent and maximum permeability caused by reset current amplitude were observed. A method for testing and specifying a core for an NDRO application is proposed.