The LOG300 comes with an internal offset correction loop (OCL) designed to correct for any small offset voltage errors due to external factors or due to the internal gain mismatch. The LOG300 internal gain blocks offer very high gain; therefore, any small error voltage is sufficient to saturate the respective gain block resulting in degradation of dynamic range.

The Offset_Cap (see Section 6) sets the time constant of the offset correction loop. Set the value of the OCL pole to less than the incoming signal frequency so that the OCL does not respond to the incoming signal. Use the following formula to calculate the value of Offset_Cap based on the frequency of the incoming signal.

Where

• Offset capacitor must never be less than 1nF. If the formula yields a value of C_{Offset_Cap} less than 1nF, use 1nF.
• Using a value of C_{Offset_Cap} greater than the calculated value using above equation is acceptable since the OCL loop is set to a lower frequency.