Gilbert Multiplier cell:
The Gilbert multiplier cell is a modification of the emitter coupled cell and this allows four – quadrant multiplication. Therefore, it forms the basis of most of the integrated circuit balanced Multipliers. Two cross- coupled emitter- coupled pairs in series connection with an emitter coupled pair form the structure of the Gilbert multiplier cell.
The collector current of Q3 and Q4 are given by
Similarly, the collector current of Q5 and Q6 are given by
collector current IC1 and IC2
of transistors Q1 and Q2 can be expressed as
Substituting the above equation in IC3 and IC4, we get
Similarly substituting Ic2= in Ic5 and IC6 , we get,
The differential output current I is given by
∆I =IL1 - IL2
= (IC3 +IC5) - ( IC4+IC6)
=IC3 - IC6)-(IC4 - IC5)
∆I=IEE tanh( V1/2VT) tanh(V2/2VT)
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