We intend to measure the open-loop gain (A_open) of an actual operational amplifier. The magnitude of A_open is in the range of 10^6 V/V. However, the signal generator in measurement setup can supply minimal voltage of 1 mV, and the oscilloscope used at amplifier output can measure maximal voltage level of 10 V. Can you design a simple measurement setup using this signal generator and oscilloscope, and accurately measure the A_open? Please describe your measurement design in detail.