Current correlator
Input: $I1$ and $I_{2}$
Output: Correlation between $I1$ and $I_{2}$
Settings:
Notes: For it to work all must be in Regimes > Subthreshold Regime. $M_{1}$ is in ohmic region, $M_{2}$ is in saturation. $V_{s}$ is = 0V
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The current correlator measures the correlation between unidirectional input currents.
Mead recognized that in subthreshold operation, the current-correlator circuit in Fig. 6.12 computes a measure of the correlation between its two input currents.
$I_{out} = \frac{I_{1}I_{2}}{(I_{1}+I_{2})}$
(exprimer $e^{Vs}$ pour trouver)
The n-input current correlator computes the parallel combination of the
input currents. The maximum number of inputs can be large, because the
only requirement for correct circuit operation is that the top transistor in the
correlator be saturated. However, the output current scales as $\frac{1}{n}$.
Strength ratio:
(the scaling factor)
