Browse Prior Art Database

Cascode Exclusive OR

IP.com Disclosure Number: IPCOM000086849D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Gersbach, JE: AUTHOR

Abstract

This circuit is a five-input exclusive OR circuit comprising transistors 1 to 19. It operates with one principle unit of current which is switched through the five-level cascode tree to a true output terminal 32 or a complement output terminal 33 depending on whether the number of input variables are even or odd.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 59% of the total text.

Page 1 of 2

Cascode Exclusive OR

This circuit is a five-input exclusive OR circuit comprising transistors 1 to 19. It operates with one principle unit of current which is switched through the five- level cascode tree to a true output terminal 32 or a complement output terminal 33 depending on whether the number of input variables are even or odd.

Transistor 19 is the principle current source, and its base is driven by a voltage source circuit 34 whose value is Vbe plus 0.2 volts. The input 35 at the base of transistor 20 is driven by a small voltage swing above and below +3 volts. Transistors T20 and T21 together form a current switch whose output is a differential voltage, the most positive side of which is at +5 volts. Inputs G1 and F1 are supplied at the base of transistor T22 and the base of transistor T23, respectively, and are differential inputs. They are driven by an output similar to that of this exclusive OR circuit and are translated down by one Vbe to prevent saturation of transistors T5 through T8. Each succeeding level is translated down by another Vbe. Inputs G2 and F2 supplied to the bases of transistors T24 and T25, respectively, and inputs F3 and G3 supplied to the bases of transistors T28 and T29, respectively, are similar to inputs G1 and F1.

The input 36 is driven by a large transistor-transistor-logic voltage swing and an input clamp diode D1 is needed to limit the highest up level. This prevents saturation of transistor T31 which, together with transis...