Hi,
I want to design a 4-16 decoder implementing thermometric code.I would appreciate it if anyone tell me how to do this at transistor level.

 

CD4067 is a pretty old 5 Volts TTL integrated IC that decode 4 to 16 lines. You should find it using google.

Alberto

 

CD4067 is a pretty old 5 Volts TTL integrated IC that decode 4 to 16 lines. You should find it using google.

Alberto

CD4067 is CMOS not TTL.

Ken

 

I Googled " thermometric code " and found more than wished for, except for a definition . Another 4 line[ non thermo.. ] decoder is 24 pin CMOS ,4515.

 

Hey vikkie - can you help us out with a quickie definition of thermometric code?

 

Thermometric code is simply binary code where each digit has the same place value. If you have a string of comparators, such as in a flash a/d converter, what you get out is thermometric code.

Eric

 

Thermometric = unary

00 = 000
01 = 001
10 = 011
11 = 111

 

Thank you.

 

Thanx for the response.Actually i have to design it using CMOS transistors.I cannot use a built-in decoder.i want to know the design technique for this decoder

 

Are CMOS transistors available? Are CMOS inverters allowed, such as 74C04 & 4009 with open drain,ea. 6 per chip?

 

Using duffy's example I came up with this scheme. Uses home built negative nand gates and + nor gates. It would be slow as there is a lot of rippling down. The outputs are inverted.Page was not big enough for 12-15.

 

Wow, that's going to be well over a hundred transistors. Hope you have a good soldering iron, vickie.

 

Are CMOS transistors available?

The CD4007 has transistors that can be used directly. There are three matched complemetry pairs. One pair is wired as an inverter, but the other two pairs can be used as transitors for general purpose.

 

If a few pins are strapped together the 4007 gives three CMOS transistors, but how can they be converted into and gates?

 

If a few pins are strapped together the 4007 gives three CMOS transistors, but how can they be converted into and gates?

Who cares. Small error on print, gate 11 out should go to gate in nor's on 10. also ,all1's inputs are paralled,as with 2's 4's & 8's.