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How is logic effort calculated?
The logical effort of a two-input NAND gate is calculated to be g = 4/3 because a NAND gate with input capacitance 4 can drive the same current as the inverter can, with input capacitance 3. Similarly, the logical effort of a two-input NOR gate can be found to be g = 5/3.
What is the logical effort of an inverter?
DEF: Logical effort is the ratio of the input capacitance of a gate to the input capacitance of an inverter delivering the same output current.
What is meant by logical effort?
DEF: Logical effort is the ratio of the input capacitance of a gate to the input capacitance of an inverter delivering the same output current. D Measured from delay vs.
What do you mean by logical effort?
What is inverter delay?
The propagation delay of a logic gate e.g. inverter is the difference in time (calculated at 50% of input-output transition), when output switches, after application of input. The delay is usually calculated at 50% point of input-output switching, as shown in above figure.
How does logical effort relate to unit inverter?
Logical effort normalizes the output drive capability of a gate to match a unit inverter How much more input capacitance does a gate need to present to offer the same drive as an inverter? g = 1 g = 4/3 g = 5/3 4 Computing Logical Effort
How to calculate the logical effort of a gate?
Computing Logical Effort DEF: Logical effort is the ratio of the input capacitance of a gate to the input capacitance of an inverter delivering the same output current. Measure from delay vs. fanout plots Or estimate by counting transistor widths Logical Effort of Other Gates
How are P / N ratios apply to static CMOS gates?
P/N ratios apply to other static CMOS gates besides inverters. For example, a normal skew NAND2 gate uses equal sized NMOS and PMOS transistors because the NMOS are in
How to estimate the logical effort of a ring oscillator?
Example: Ring Oscillator Estimate the frequency of an N-stage ring oscillator Logical Effort: g = 1 Electrical Effort: h = 1 Parasitic Delay: p = 1 Stage Delay: d = 2 so d abs= 80ps Period: 2*N*d