Delay parameters.pptDelay parameters.ppt

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1. TIMING MODELS - COMBINATION CELLS

2. combinational timing arcs 1 .Let us consider two input and cell , both the timing arcs when the input is raising transition and the output is raising tranition is positive unate 2 . for 2 input and cell there are four delays A-Z : Output rise A-Z : Output fall B-Z :Output rise B-Z : Output fall

3. Delay parameters : Propagation delay : It is measured b/w 50% transition points of input wavefrom and output wavefrom Rise propagation delay(Tplh) : The signal delay time b/w 50% of the input to the 50% of the output , when the output rises from low to high level. Fall propagation delay (Tphl) : The signal delay time b/w 50% of the input to 50% of the output, when the output falls from high to low level. Average propagation delay (Tp) = (Tphl + Tplh)/2

4. lnverting gate

5. Rise transition delay : The time taken by the signal to rise from 10% to 90% of its maximum value Fall transition delay : The time taken by the signal to fall from 90% to 10% of its maximum value pin (OUT) { max_transition : 1.0; timing() { related_pin : "INP1"; timing_sense : negative_unate; cell_rise(delay_template_3x3) { index_1 ("0.1, 0.3, 0.7"); index_2 ("0.16, 0.35, 1.43"); values ( \ "0.0513, 0.1537, 0.5280", \ "0.1018, 0.2327, 0.6476", \ "0.1334, 0.2973, 0.7252"); }

6. rise_transition(delay_template_3x3) { index_1 ("0.1, 0.3, 0.7"); index_2 ("0.16, 0.35, 1.43"); values ( \ "0.0417, 0.1337, 0.4680", \ "0.0718, 0.1827, 0.5676", \ } cell_fall(delay_template_3x3) { index_1 ("0.1, 0.3, 0.7"); index_2 ("0.16, 0.35, 1.43"); values ( \ "0.0617, 0.1537, 0.5280", \ "0.0918, 0.2027, 0.5676", \ "0.1034, 0.2273, 0.6452"); } fall_transition(delay_template_3x3) { index_1 ("0.1, 0.3, 0.7"); index_2 ("0.16, 0.35, 1.43"); values ( \ "0.0817, 0.1937, 0.7280", \ "0.1018, 0.2327, 0.7676", \ "0.1334, 0.2973, 0.8452")

7. cell rise or tplh = f (CL , input fall transition) cell fall or tphl = f (CL , input rise transition) o/p transition time (rise) = f(CL, i/p fall transition time) o/p transition time (fall) = f(CL, i/p rise transition time) General combinational block :

8. POWER DISSIPATION MODELLING The cell library contains information related to power dissipation in the cells. This includes active power as well as standby or leakage power. As the names imply, the active power is related to the activity in the design whereas the standby power is the power dissipated in the standby mode, which is mainly due to leakage power dissipation classified into two types 1. static power 2. Dynamic power

9. static power dissipation are refered as standby power or leakage current subthreshold leakage , gate oxide leakage, junction leakage Dynamic power classified into two types 1. switching power 2. Internal switching power cell (NAND2) { . . . pg_pin (VDD) { pg_type : primary_power; voltage_name : COREVDD1; . . . }

10. Cell leakage power : Leakage power is specified for each cell in the library. For example, an inverter cell may contain the following specification: cell_leakage_power : 1.366; This is the leakage power dissipated in the cell - the leakage power units are as specified in the header of the library, typically in nanowatts