Questions related to "EEVBlog 1436 - The TOP 5 Jellybean OPAMP's" - Page 1
Forum section: electronics / beginners

author: matrixofdynamism
author_rank: Regular Contributor
timestamp: July 16, 2023, 12:56:52 pm
content: I recently saw this video from eevblog "EEVBlog 1436 - The TOP 5 Jellybean OPAMP's". I am an FPGA/ASIC design and verification person and not analogue design engineer. But of course, FPGAs and ASICs could be interfacing with analogue electronics too so I am still interested to learn more about this.In this video Guru Dave talked about and recommended these parts for different applications:LM358 "Industry-Standard Dual Operational Amplifiers"TL071/72/74 "TL07xx Low-Noise FET-Input Operational Amplifiers"LMV358 "LMV3xx Low-Voltage Rail-to-Rail Output Operational Amplifier"LM324 "LMx24, LMx24x, LMx24xx, LM2902, LM2902x, LM2902xx, LM2902xxx Quadruple Operational Amplifiers"RC4558 "RC4558 Dual General-Purpose Operational Amplifier"NE5532 "NE5532x, SA5532x Dual Low-Noise Operational Amplifiers"OP07 "OP07x Precision Operational Amplifiers"I have a few questions about this topic.1. Since such robust parts exist that have passed the test the time and are still relevant, what is special about the latest in op-amp technology that these are not able to match?2. What could be a few examples of non-jelly bean op-amps that are used a lot?From my limited understanding, I believe that non-jelly bean op-amp would be aimed at specific applications which could be related to Space or perhaps Power electronics. It could be related to high reliability applications like Medical for example. Is this correct?

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 16, 2023, 01:15:41 pm
content: 1. Modern techmnology tends to low-voltage opamps, Rail-to-rail opamps, low-voltage RtoR opamps, low-consumption.Modern opamps typically don't have phase reversal effect (which some old jelly-bean have).2. Just filter or sort by price on any online shop site. You'll find a lot useful opamps. For example, my favorite ones are LM4562 (low-distortion), LM6172 (high speed, high output current).

author: Kleinstein
author_rank: Super Contributor
timestamp: July 16, 2023, 02:54:11 pm
content: A feature not found in the list is a rail to rail input OP amp. I would consider the MCP6001/2/4 as yellybean parts for this category. AFAIK it is already quite high in the list of most produced chips.Another class not in the list are auto zero OP-amps (may need separate one for low and high voltage types).New technologies provide especially better CMOS OP-amps for low voltage and AZ OP-amps. A general tendency is to get lower supply currents for a similar speed. Here it helps having finer structures.Another point is that many old processes has only poor quality lateral PNP transistors. Finer structures can improve on the quality of lateral PNP transistors.An OP-amp I have used quite a bit lately is the OPA202, as an upgrade to the OP07 with lower supply current, less bias and higher speed. It is still not a yelly bean part, as it is single source.

author: KE5FX
author_rank: Super Contributor
timestamp: July 16, 2023, 05:41:32 pm
content: QuoteWith the older parts, you often had to compromise one spec to optimize another. Want an ultra-high impedance input? It will be more expensive and/or slower and/or noisier. Want ultra-low drift? You'll need a chopper-stabilized part that will cost more and consume more power, and may have spurs or charge-injection problems. Need ultra-low noise? It will take a lot of power and cost a lot, it may require higher supply voltages to get the headroom you need, and it may have other undesirable traits like phase reversal at the rails. Need ultra-high bandwidth? You'll probably have to use a current-feedback amp to get that, which will have worse DC attributes, worse overrange recovery time, and won't work in some circuits at all. Etc., etc.Newer opamps tend to be better at combining the desirable attributes from multiple classes of older parts. Lots of newer parts can be treated as "jellybeans" with extremely good performance across multiple categories.

author: matrixofdynamism
author_rank: Regular Contributor
timestamp: July 16, 2023, 11:25:13 pm
content: From what I know, chopper means helicopter. So what is a chopper-stabilized Op Amp? I have not come across this term before.By the way, I was looking for top 5 jellybean switched mode PSU but did not find any such video from Guru Dave.

author: TimFox
author_rank: Super Contributor
timestamp: July 16, 2023, 11:36:05 pm
content: Chopper-stabilized DC amplifiers go back to before WWII.A chopper-stabilized op amp is one in which a switch is used to zero the voltage offset periodically.Historically, this was an electromechanical switch, but FET switches are used in monolithic devices now.A discussion from Analog Devices:https://www.analog.com/media/en/training-seminars/tutorials/MT-055.pdfThey are used when accurate DC voltages are needed, especially with small signal voltages.

author: David Hess
author_rank: Super Contributor
timestamp: July 17, 2023, 01:08:26 am
content: Modern parts can take advantage of complementary processes which have relatively matched NPN and PNP transistors, or CMOS, but this also makes them lower voltage. Finer design rules also make for smaller chips so they can fit inside smaller packages.Chopper stabilized parts are not a panacea for higher precision because of higher noise and bias current.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 17, 2023, 07:02:56 am
content: The chopper stabilized OP amps have there own problems with switching spikes that can cause unexpected effects (sensitivity to source impedance in the higher MHz range). The input bias is not that bad, compared to other precision OP-amps that are usually BJT based. The bias is just large compared to other CMOS OP-amps. They are still a nice solution to get low offset and low drift and by now they are often more cost effective than a classic precision OP-amp with very low offset. Usually they are seen as a class of zero dift OP-amps together with similar auto-zero OP-amps.As CMOS parts there is still quite some new improved (even if just lower costs) parts coming out from multiple sources. So far I don't see a part of these to qualify as a true yelly-bean part (common prototype part for a class of similar parts). Maybe the ICL7650 was close to this, but by now the external capacitors make it a bit outdated and an oddity.