CMOS 1963 Verify Near Zero Static Current Both States

# Verify Near-Zero Static Current in Both Logic States: Not Exactly Zero, But Orders of Magnitude Away From the Alternative

## 1. Why Step 1's Equation Finally Needs a Number Behind It

This step holds the finished gate's input fixed in each of its two static logic states in turn, waits out any switching transient, and measures the actual current drawn from the supply in steady state — the first measurement in this series to check Step 1's own theoretical claim and Step 5's physical wiring against a real number, rather than an equation or a layout. Step 1's own relation, $I_{\text{supply}} = V_{DD}/(R_{\text{ON}} + R_{\text{OFF}})$, predicted this current would vanish as $R_{\text{OFF}}$ grows large — but no real transistor's off-state resistance is truly infinite, and a properly fabricated MOS device still conducts a small subthreshold leakage current even when nominally cut off. This step measures that leakage directly, and the honest result is not mathematical zero, but a current many orders of magnitude below what a 1960-style resistor-loaded gate draws whenever its own load resistor is active — a distinction worth measuring precisely rather than simply asserting.

$$I_{\text{static}} = I_{\text{leak,off}} \ll I_{\text{resistor-loaded}} = \frac{V_{DD}}{R_{\text{load}}}$$

where $I_{\text{leak,off}}$ is the measured subthreshold leakage current of whichever transistor in the pair is nominally off, and $I_{\text{resistor-loaded}}$ is the steady current a 1960-style resistor-loaded gate would draw from the same supply — this step's own measured $I_{\text{static}}$ is not zero, but it sits far enough below $I_{\text{resistor-loaded}}$ that the two numbers belong on different scales entirely, which is exactly what Step 1's idealized equation predicted in the limit without ever being checked against a real device.

A Logarithmic Scale, Because a Linear One Can't Show Both Bars measured static current, both device types, on a scale wide enough to hold the real gap supply current, log scale Iresistor-loaded, 1960-style Istatic, measured, this gate Istatic = Ileak,off ≪ Iresistor-loaded = VDD / Rload small, measurable, and nonzero — not the idealized zero the limit in Step 1 suggested

## 2. Real Diagram: A Fixed Bias, a Sensitive Meter, Two States

The apparatus below is deliberately simple — a DC supply holding the gate's input fixed in one logic state at a time, with a sensitive current meter placed in series with the supply rail to catch a current small enough that an ordinary ammeter would read it as zero.

Fixed Input, Sensitive Meter, Two States in Turn each state held long enough for the switching transient to settle completely DC SUPPLY FIXED INPUT GATE UNDER TEST SENSITIVE CURRENT METER in series with the supply rail TWO READINGS, ONE PER STATE input low: Istatic measured input high: Istatic measured again both readings should land near the same small floor, regardless of which device is nominally off

## 3. The First Measurement in This Project Characterizing a Circuit, Not a Device

The 1962 series' own Step 6 was this project's first measurement of a device's internal electrostatic state rather than its terminal behavior, a genuine departure from every breakdown voltage, resistance, or switching time this project had measured before it. This step marks a different kind of first: the first measurement in this project's history whose subject is an entire finished gate's own quiescent behavior, not any single transistor's own parameter. Step 1 derived what this gate's static current should theoretically approach; Step 5 built the physical circuit that claim depends on; this step is where the two meet a real meter for the first time, and the honest result — small, nonzero, dominated by leakage rather than by any resistive path — is a genuinely stronger claim than Step 1's own idealized limit, because it is measured rather than merely derived.

Step 6 does not simply confirm that this gate draws less current than a resistor-loaded one; it puts an actual number on how much less, closing the gap between what Step 1 predicted in principle and what this series has now proven in practice.

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