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

-- FIGURE 6.11 




-- ENTITY DECLERATION OF AN INVERTER USING 
   RESISTANCE AND CAPACITANCE PHYSICAL TYPES :

ENTITY inv_rc IS
  GENERIC (c_load : capacitance := 66 ffr);
  PORT (i1 : IN qit; o1 : OUT qit);
  CONSTANT rpu : resistance := 25000 ohms;
  CONSTANT rpd : resistance := 15000 ohms;
END inv_rc;

--



-- DOUBLE -DELAY ARCHITECTURE OF THE INVERTER WITH
   RESISTANCE AND CAPACITANCE PHYSICAL TYPES :

ARCHITECTURE double_delay OF inv_rc IS
  CONSTANT tplh : TIME := (rpu / 1 l_o) * (c_load / 1 ffr) * 3 FS / 1000;
  CONSTANT tphl : TIME := (rpd / 1 l_o) * (c_load / 1 ffr) * 3 FS / 1000;
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;
--