The Wheatstone bridge where antiparallel diodes are place be

The Wheatstone bridge where antiparallel diodes are place between nodes A and B. Can you find the small-signal voltage across nodes A and B? Assume the diodes have i_D = I_s (e^v/D/v^r - 1)

Solution

Here clearly it is wheatstone bridge.So voltage at point A and voltage at point B are same when bridge is balanced.

This bridge bbalance condition occurs when R1*R4 = R2*R3

so under this condition Va=Vb