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Current Mode Latch

IP.com Disclosure Number: IPCOM000096570D
Original Publication Date: 1963-Jul-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Ghertmann, P: AUTHOR

Abstract

In this current mode latch, transistor A is an inverter controlled by its base. Transistor B is an emitter follower. Transistor C is an inverter through the base of which reset is made. Coupling is realized by a direct link between the emitters of transistors A and B. A bridge having resistors R1, R2, R3 and R4 sets the voltage at output S and at the base of transistor B to a proper level.

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Current Mode Latch

In this current mode latch, transistor A is an inverter controlled by its base. Transistor B is an emitter follower. Transistor C is an inverter through the base of which reset is made. Coupling is realized by a direct link between the emitters of transistors A and B. A bridge having resistors R1, R2, R3 and R4 sets the voltage at output S and at the base of transistor B to a proper level.

The latch is set on when input E is at + 1v. Transistor A is blocked, transistor B conducts, and the coupling of the emitters maintains transistor A blocked even if E falls to - 1v. Output S is at low level - 1v.

Reset is obtained when R is at - 1v. Then C conducts, B is blocked and A conducts. B is maintained blocked even when R comes to + 1v and C stops conducting. The latch is then on reset condition, A only conducting, and S is at high level (+ 1).

When both inverters A and C are conducting, during the reset before R is at + 1v., S is at a voltage higher than 1 v. This voltage can be made to approach 1 v., of necessary, by a clamping diode.

The values of the resistors are, in ohms: R1 = 270, R2 = 100, R3 = 15, R4 = 315, R5= 600, R6 =3300.

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