The production process is also varying. You have two ways to accomplish a dual jfet
1. two dies, one package
2. one die, one package (monolithic)
In case one you need to check every die and combine them by matching values. But two dies in one package might be more expensive and you need to measure every jfet ...sort etc. not sure if a company might do this for a cheap price. And thermal coupling is not really good compared to monolithic.
In the second case both jfets are on one die. It is possible to adjust production parameters so tightly that one can say that they are closely matched. But you will never get that close as mentioned in the case before. Or you have to throw away a lot of dies. But lower wafer cuts, easier to pack, just a few spot checks (eg 1 in 100 or 1 in 1000) to assume if the fets are in the production range (eg.: Idss matching Toshiba duals around 3% and Linear Systems around 10%)
If you do matching by hand you will have more or less case 1. For instance, you buy a batch of 100 parts and you will most probably find 1 pair idss matched below 1% (2sk170bl).
Keep in mind dual jfets are no "massproduct" if you compare them with other semiconductors so the price is higher anyway. Throwing away dies would drive the prices a lot more.
1. two dies, one package
2. one die, one package (monolithic)
In case one you need to check every die and combine them by matching values. But two dies in one package might be more expensive and you need to measure every jfet ...sort etc. not sure if a company might do this for a cheap price. And thermal coupling is not really good compared to monolithic.
In the second case both jfets are on one die. It is possible to adjust production parameters so tightly that one can say that they are closely matched. But you will never get that close as mentioned in the case before. Or you have to throw away a lot of dies. But lower wafer cuts, easier to pack, just a few spot checks (eg 1 in 100 or 1 in 1000) to assume if the fets are in the production range (eg.: Idss matching Toshiba duals around 3% and Linear Systems around 10%)
If you do matching by hand you will have more or less case 1. For instance, you buy a batch of 100 parts and you will most probably find 1 pair idss matched below 1% (2sk170bl).
Keep in mind dual jfets are no "massproduct" if you compare them with other semiconductors so the price is higher anyway. Throwing away dies would drive the prices a lot more.
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