PTAT current source with variable slope

[analog_match]

I need to design a circuit that behaves like a PTAT current source but has capability where some parameter can be adjusted (like say trimming resistors etc) to change the slope.

I have attached a rough diagram for explanation.

Has anyone done this before or can point me to some literature to do more research on this I'll be very greatful.

Thanks

 

[kishore2k4]

IIRC, The resistance you use to tune the current in your typical PTAT circuit is doing this.

In the above equation you can see that the slope of I_ptat can be controlled by the resistor R, neglecting the tempco of the resistor.