LM13700

SNOSBW2F – NOVEMBER 1999 – REVISED NOVEMBER 2015

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Feature Description (continued)

(5)

7.3.2 Linearizing Diodes

For differential voltages greater than a few millivolts, Equation 3 becomes less valid and the transconductance

becomes increasingly nonlinear. Figure 19 demonstrates how the internal diodes can linearize the transfer

function of the amplifier. For convenience assume the diodes are biased with current sources and the input

written as follows:

(6)

Since the diodes and the input transistors have identical geometries and are subject to similar voltages and

temperatures, the following is true:

(7)

Notice that in deriving Equation 7 no approximations have been made and there are no temperature-dependent

practice, replacing the current sources with resistors will generate insignificant errors.

7.4 Device Functional Modes

Use in single ended or dual supply systems requires minimal changes. The outputs can support a sustained

short to ground. Note that use of the LM13700 in ±5 V supply systems requires will reduce signal dynamic range;

7.4.1 Output Buffers

Each channel includes a separate output buffer which consists of a Darlington pair transistor that can drive up to

20mA.

10

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