Abstract :
To date, nanosecond circuitry has been based mainly on two devices--the transistor and the tunnel diode. Unfortunately, the speed advantages of the tunnel diode cannot be utilized because the current gain is limited by practical tolerance requirements. Therefore, any circuits designed "around" these two devices are either practical, but limited to the speed of the transistor, or impractical, for general purpose logic, with the speed performance of the tunnel diode. The region of the tunnel diode gain bandwidth curve which is limited by tolerances can be exploited by using a storage diode as an interstage current amplifier or charge transformer. The operation of the storage diode is discussed, and charge gain bandwidth criteria are developed from the physical equations describing the device. Charge control switching curves are developed for the tnnnel diode which define its operation as a charge amplifier. The combination of tunnel diode and charge transformer (TDCT Logic) enables a wide variety of logic functions to be obtained with a gain bandwidth tolerance performance previously unattainable in nanosecond logic circuitry. To demonstrate this capability a novel "NOR" circuit is described and a worse case analysis of the fan out tolerance performance is given in the Appendix.
