How to use a current source with current control pin of LM13700
The circuit you show is a current sink. For the LM13700 Iabc input you need a current source. 

The above circuit just needs to be 'flipped'. Use a PNP transistor. The voltage source is relative to Vcc now, so you might use a shunt reference such as an LM4040 or TL431 if the power supply is deemed not accurate enough.

Be sure to respect the common mode voltage range of the op-amp and don't use too low a reference voltage.  







simulate this circuit &ndash; Schematic created using CircuitLab