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Very High Speed Latch for Data Communication System

IP.com Disclosure Number: IPCOM000049579D
Original Publication Date: 1982-Jun-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Boudon, G: AUTHOR

Abstract

Shown in the drawing is a latch which can be set or reset by pulses having a very short length of time or by the phase difference between two signals. The latch is primarly used to retrieve and store the data in a high speed transmission scheme in serial mode, based on differential transmission and a coding of the data by phase modulation. Signals R and S come from the receiver part of the transmission scheme.

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Very High Speed Latch for Data Communication System

Shown in the drawing is a latch which can be set or reset by pulses having a very short length of time or by the phase difference between two signals. The latch is primarly used to retrieve and store the data in a high speed transmission scheme in serial mode, based on differential transmission and a coding of the data by phase modulation. Signals R and S come from the receiver part of the transmission scheme.

The latch, comprising transistors T7 and T8 and resistors R3 and R4, stores the data D, and transistors T5 and T6 allow the data to be written into the latch.

In standby mode, R (reset) and S (set) are equal and the voltage drops in resistors Rl and R2 are equal, thus transistors T5 and T6 are OFF.

If the difference between S and R is positive, transistor T1 becomes ON and T2 OFF. Transistor T6 becomes ON since its emitter goes down and its base goes up until the voltage between the base emitter goes from one VF of Schottky barrier diode (SBB) initially to one VBE, VF being the voltage drop in an SBD and VBE being the base emitter voltage of a transistor.

If D is up and D down, i.e., transistor T7 is ON, the latch contains a "0". When a collector current appears in transistor T6, transistor T7 is switched OFF since its base goes down due to the voltage drop in resistor R3. When T7 switches OFF, T8 becomes ON and a "1" is stored in the latch.

In this case, with S-R positive, if the cell contains a "1", the...