TABLE OF CONTENTS We conclude this chapter with a brief mention of some miscellaneous functions which can be realized in translinear loop (TL) form or simply through dependence on the logarithmic V BE of the BJT, using what we have here called translinear networks (TN circuits).
Quite a large catalog of functions has been generated over the past twenty years, many of them being discovered rapidly in the late 60's and early 70's and left to gather dust. In this section we will only include those which are known to have practical utility. The reader is encouraged, however, to try out "what-if' experiments. We have said very little so far about the new possibilities opened up by the recently- available complementary processes, having PNP transistors which exhibit accurate translinear properties. A thorough discussion of these possibilities will have to wait until a later date, but this section will conclude with a brief mention of the topic.
Figure 2.52 shows one of the earliest extensions of the basic multiplier cells, which was called the "product/quotient" circuit [6] and the name stuck. It is readily shown that the current Io is not very important, as long as it is sufficient to support the output. The TL equation is
(1-a)Io Iu aIo = (1-a)Io Iy Ix
where a is a temporary variable in the range 0 The utility of this circuit lies in the fact that it can generate this output using only currents which sink toward the negative... 
