How does an Analog IC Tester test an OP-AMP?

[CMOS]

Can anyone tell me how does an Analog IC Tester test an OP-AMP? What parameter of op-amp does it check?

I want to build an op-amp tester using micro-controller. What I am thinking is to apply voltage at appropriate pins in comparator mode and read the analog values from output pins.

Is just checking the op-amp in comparator mode enough to prove that it is working or I have to set up some feedback loop and also test it in amplifier mode?

 

[runom]

op-amp tester

are u also taking care of open loop gain, ugb,cmrr?
i think measuring the bias current and offset voltage is also necessary, i hope u take care of those things also.

 

[sankudey]

Re: Analog IC Tester

In comparator mode openloop gain can be tested....what about frequency response and use in buffer mode....
some feedback config need to be tested...i guess....

sankudey

 

[yousafzai]

Re: Analog IC Tester

I think u should first implement a library in ur application and if the user selects a specific IC then functions related to that IC can be checked. For this purpose u need to have the required circuitry in ur tester to support the testing.

 

[CMOS]

Re: Analog IC Tester

I think u should first implement a library in ur application and if the user selects a specific IC then functions related to that IC can be checked. For this purpose u need to have the required circuitry in ur tester to support the testing.

Yeah, I understand that...I have already made a digital IC tester, so I know how to create test vectors. Checking in closed-loop will be difficult since I need to inter-connect IC pins electronically. I want my tester to be able to test several op-amps.

Any ideas on how to implement it?

 

[aryajur]

Re: Analog IC Tester

The kind of tests you should perform should be ideally based on the application you are testing the opamp for. There are lots of opamp specifications thatmay need to be tested.
You would definitely need to connect and disconnect the pins electronically. This can create problems like capacitively loading the pins and give you false readings for a say the Frequency response if you go to higher frequencies to get the whole plot for opamps. So this would need a very careful design accounting all the capacitances of the switches you use (maybe CMOS), and then you can know the limitations of doing the testing.
I think some of the features that can be tested and would be useful would be:
Open loop gain at DC, Phase margin for a known capacitive loading, offset voltage, linearity, Common Mode range, Common Mode Rejection Ratio, Power Supply Rejection Ratio, current sourcing capability.

 

[qutang]

Analog IC Tester

you can fisrt download a datasheet ,there are the data you can test.

 

[zenisle]

Analog IC Tester

Power Supply Rejection Ratio, current sourcing capability.

Added after 2 hours 28 minutes:

op gain, phase margin, psrr, cmrr, snr

 

[yousafzai]

Re: Analog IC Tester

Yeah, I understand that...I have already made a digital IC tester, so I know how to create test vectors. Checking in closed-loop will be difficult since I need to inter-connect IC pins electronically. I want my tester to be able to test several op-amps.

Any ideas on how to implement it?

I suggest implementing a switch network will do the job....Plz give me some time ....i have one analog IC tester with me but i have not yet openend me. Let me open it and figure out whats inside and then i can better update you....

 

[CMOS]

Re: Analog IC Tester

I suggest implementing a switch network will do the job....Plz give me some time ....i have one analog IC tester with me but i have not yet openend me. Let me open it and figure out whats inside and then i can better update you....

I was thinking on the same lines to implement a switch matrix using EPABX switch ICs like MT8816 to allow any pin to be connected to any other pin on the socket. This would be useful for testing op-amp in closed loop (unity gain buffer) configuration.

It would be of great help if you let me know whats inside your analog IC tester. I am eagelry waiting for your reply.

Thanks.

 

[CMOS]

Re: Analog IC Tester

I suggest implementing a switch network will do the job....Plz give me some time ....i have one analog IC tester with me but i have not yet openend me. Let me open it and figure out whats inside and then i can better update you....

I know its been a long time but did you had a chance to open up your analog IC tester?

 

[dick_freebird]

Re: Analog IC Tester

A general purpose tester may not be up to the job. Back when
I was doing those kinds of products the load boards always had
at least one op amp and a bunch of relays and resistors to make
a lot of the measurements practical. For example, how are you
going to measure AVOL=80dB (A=10K) on an op amp with a
+/-1V output swing, practically speaking? Do your tester
pin electronics have 0.1mV output accuracy including noise?
All kinds of fun. Even million dollar "big iron" ATE only gets
you so far.