Amplifier and Driver Circuits for Thin Film Memories with 15 Nanoseconds Read Cycle Time
Amplifier and driver circuit design principles for an experimental 4608-bit nondestructive thin film memory with 13.5-nsec read and 60-nsec write cycle times are given. The bit noise problems inherent in the common bit sense line concept are solved by using tunnel diodes in a nonlinear balancing circuit. A further improvement of the signal-to-noise ratio is achieved by employing a noise resistant sense amplifier with nonlinear negative feedback. The word driver described is capable of delivering 700 ma pulse amplitude at 50 mc repetition rate at a pulse width of 7 nsec.
Optimum Design of the Shunt-Series Feedback Pair with a Maximally Flat Magnitude Response
In this paper, analysis and design of the shunt-series pair feedback amplifier are given. The design achieves optimum gain-bandwidth product with a maximally flat magnitude transmission for a specified gain or desensitivity. Phantom zero is used to avoid degradation of feedback bandwidth and to obtain a filter type transient response. Experimental verification of the theory is given with a medium frequency alloyed-junction transistors and HF mesa transistors. The agreement between the theoretical and experimental work is shown to be good in all cases, both in time and in frequency domains.
Planar silicon diodes and transistors
In the planar design of diodes or transistors, the device is fabricated to its final shape during the diffusion operations, rather than during a mesa operation subsequent to diffusion. The planar process involves the application of a suitable coating on the silicon surface prior to the diffusion operations so that the junctions emerge from the bulk of the material under the coating and are protected from environmental contamination. Two types of devices made by the process will be described: a planar diode and a planar NPN transistor. Dopants used in both cases are boron and phosphorus and the lateral limitation of the diffused layers is obtained by oxide masking of suitable shape. The outstanding property of planar units is the very tight distribution of diode reverse currents over a large sample of units. Values of these currents are in close agreement with those calculated from bulk reverse currents. Life test data indicate improved reliability at high temperature storage over mesa units of similar characteristics. Data on unencapsulated units will also be presented.