Circuit Oscillation Analysis

I have the attached circuit as a Voltage Controlled (V_Control) Current Source (I-Load).

This circuit has an stability issue. When V_Control drops from 3.3 V to 0 volts the circuit works fine at room temperature. But when the temperature is reduced to -45 degrees, it starts to oscillate.

I cant figure out why? Possible causes are:

  1. Slamming on the rail of LT1013 cause the pole in its output stage move to left reduce phase margin
  2. OPAMP has multiple loop feedbacks and the delay on Q133, Q132, INA193A increases during transition.
  3. OPAMP is in the non linear mode acting as a comparator

Circuit is:

The output waveform (U89 is the LT1013) at room temperature is:

The output at -45 degree C is:


Please let me know if you can advise on the source of oscillation here.


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