-- Copyright © 1993 by  McGraw-Hill, Inc. and Zainalabedin Navabi

-- FIGURE 6.8 




-- ENTITY DECLERATION OF AN INVERTER WITH RC TIMING PARAMETERS :

USE WORK.basic_utilities.ALL;
ENTITY inv_rc IS
  GENERIC (c_load : REAL := 0.066E-12);  -- Farads
  PORT (i1 : IN qit; o1 : OUT qit);
  CONSTANT rpu : REAL := 25000.0;  -- Ohms
  CONSTANT rpd : REAL := 15000.0;  -- Ohms
END inv_rc;
--



-- DOUBLE -DELAY ARCHITECTURE OF THE INVERTER WITH RC TIMING PARAMETERS :

ARCHITECTURE double_delay OF inv_rc IS
  CONSTANT tplh : TIME := INTEGER ( rpu * c_load * 1.0E15) * 3 FS;
  CONSTANT tphl : TIME := INTEGER ( rpd * c_load * 1.0E15) * 3 FS;
BEGIN
  o1 <= '1' AFTER tplh WHEN i1 = '0' ELSE
        '0' AFTER tphl WHEN i1 = '1' OR i1 = 'Z' ELSE
        'X' AFTER tplh;
END double_delay;
--