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# Creation of Boolean Equations With Multiple Strengths for FET Networks

IP.com Disclosure Number: IPCOM000043671D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 58K

IBM

## Related People

Ditlow, GS: AUTHOR [+2]

## Abstract

The determination of Boolean equations from an arbitrary FET network is available as an algorithm in which there are two transistor strengths defined as hard and soft. Transistors with a hard strength have low resistance when turned on, while transistors with a soft strength have high resistance. The ratio of resistances for soft to hard devices is 10:1. There are, however, applications when a higher ratio is needed. To see how the algorithm generalizes to multiple strengths, the equations for two strengths will be derived. The equations become apparent if the truth table in Fig. 1, which follows the conventions in the lattice diagram, is examined. To determine (T,F,E,m) from (S0,S1,H0,H1), the rules are applied according to the lattice diagram.

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Creation of Boolean Equations With Multiple Strengths for FET Networks

The determination of Boolean equations from an arbitrary FET network is available as an algorithm in which there are two transistor strengths defined as hard and soft. Transistors with a hard strength have low resistance when turned on, while transistors with a soft strength have high resistance. The ratio of resistances for soft to hard devices is 10:1. There are, however, applications when a higher ratio is needed. To see how the algorithm generalizes to multiple strengths, the equations for two strengths will be derived. The equations become apparent if the truth table in Fig. 1, which follows the conventions in the lattice diagram, is examined. To determine (T,F,E,m) from (S0,S1,H0,H1), the rules are applied according to the lattice diagram. Two logical signals can be combined into a signal as (i) A stronger signal will override a weaker, and the weaker signal can be ignored completely (ii) If the signals have the same strength and state, the resulting signal has this strength and state (iii) If the signals have the same strength, but different states, the resulting signal

has this strength and state x. Example: (S0,H0,S1,H1) = (1,0,1,1) returns (T,F,E,m) = (1,0,0,0) by (i)

(S0,H0,S1,H1) = (1,0,1,0) returns (T,F,E,m) = (0,0,1,0)

by (iii) The described concept can be generalized to n strengths. For convenience assume that strengths are ordered S<H<x<y<z. The equations in minimized PLA (prog...