What must be checked before using the High noise margin relation?

Use the family levels and measure margins in DC.

14. Logic families and gates

High noise margin

Formula

\mathrm{NMH}=V_{OH(\min)}-V_{IH(\min)}

Detail

NMH=VOH−VIH is the high noise margin between a high output and VIH.

Explore the idea

Variables

$V_{OH},V_{OL},V_{IH},V_{IL},V_M$ V
$t_{pHL},t_p$ s
$R_{\mathrm{pu}}$ Ω
fan-out and fan-indimensionless.

Conditions

Logic family on a fixed supply; static levels.

Intuitive explanation

For “High noise margin”: VOH, VOL, VIH and VIL set noise margins and the CMOS VTC inverts between rails.

Worked example

V_{OH(\min)}=4.4\,\mathrm V

and

V_{IH(\min)}=3.5\,\mathrm V

\mathrm{NMH}=0.9\,\mathrm V

Common mistakes

confusing VIH with VOH
forgetting noise margin
computing fan-out without input current

Frequently asked questions

What must be checked before using the High noise margin relation?: Use the family levels and measure margins in DC.

Also known as

VOH VOL, noise margin, CMOS VTC, fan-out, propagation delay

Conventions

V, s or dimensionless

Last reviewed: 2026-09-19

Found an error? Contact us.

Related formulas

14. Logic families and gates

High noise margin

In 14. Logic families and gates

Formula

\mathrm{NMH}=V_{OH(\min)}-V_{IH(\min)}

Detail

NMH=VOH−VIH is the high noise margin between a high output and VIH.

Explore the idea

Variables

$V_{OH},V_{OL},V_{IH},V_{IL},V_M$ V
$t_{pHL},t_p$ s
$R_{\mathrm{pu}}$ Ω
fan-out and fan-indimensionless.

Conditions

Logic family on a fixed supply; static levels.

Intuitive explanation

For “High noise margin”: VOH, VOL, VIH and VIL set noise margins and the CMOS VTC inverts between rails.

Worked example

V_{OH(\min)}=4.4\,\mathrm V

and

V_{IH(\min)}=3.5\,\mathrm V

\mathrm{NMH}=0.9\,\mathrm V

Common mistakes

confusing VIH with VOH
forgetting noise margin
computing fan-out without input current

Frequently asked questions

What must be checked before using the High noise margin relation?: Use the family levels and measure margins in DC.

Also known as

VOH VOL, noise margin, CMOS VTC, fan-out, propagation delay

Conventions

V, s or dimensionless

Last reviewed: 2026-09-19

Found an error? Contact us.

High noise margin

Tags

Detail

Explore the idea

Variables

Conditions

Intuitive explanation

Worked example

Common mistakes

Frequently asked questions

Also known as

Conventions

Related formulas

High noise margin

Tags

Detail

Explore the idea

Variables

Conditions

Intuitive explanation

Worked example

Common mistakes

Frequently asked questions

Also known as

Conventions

Related formulas