Suppose op amp is ideal and diode is exponential form Using

Suppose op amp is ideal and diode is exponential form. Using additional op amp, design a new circuit that can make Vx*Vy

(hint: log(A)+log(B)=log(A*B).

sorry. my translation is awful.

Solution

vo - v1 = io * R1

= I (e^V/nVt - 1)* R1

log( vo -v1 ) = log(I (e^V/nVt - 1)* R1)

= log(I*R1) + V/nVt