To the non-analog designer, the vast number of op-amps available from any single top-tier vendor can be overwhelming. Sure, there are selection guides and other tools, but you still have to admire it (and perhaps be just a little scared) when you see literally hundreds of distinct devices — and that's not counting their various temperature and performance grades. Frankly, it can even be a little intimidating to those who know and resonate with all the vagaries and subtle parameters of this basic building block of the analog world.
The interesting thing is that, even with so many pretty good, very good, and quite excellent op-amps already on the market, there seems to always be a need for new and better ones. Of course, “better” is the key word in this situation. What makes one op-amp better than another is not necessarily improved specifications. Instead, it may have a better combination of specs that hits a sweeter spot in the eternal struggle to balance the many tradeoffs and compromises inherent in the analog world.
Several recent introductions substantiate my feelings, as you'll see from these extracts from vendor press releases. (This is an unscientific, somewhat randomly chosen selection.)
“Linear Technology introduces the LTC2057HV, a zero-drift amplifier featuring self-calibrating circuitry that provides high DC precision and stability over changes in temperature, time, input range and supply voltage. With 5μV input offset voltage, 0.025μV/°C offset drift and 220nVP-P low-frequency noise with no 1/f noise, the LTC2057HV offers more than 140dB dynamic range while operating on a 60V (±30V) supply.”
“Texas Instruments… today introduced a fully differential, zero-drift, 36-V programmable gain amplifier (PGA). At 5μV, the PGA281 offers the lowest offset voltage in its class to improve accuracy and long-term stability… Designers can use the PGA281 in industrial signal acquisition applications, including test and measurement, strain gauges, bridge amplifiers, and medical instrumentation… [It has] an offset voltage of 25μV and an offset voltage drift of 174nV/°C with a maximum gain of 128… CMRR [is] more than 140dB.”
“Linear Technology introduces the LT6015 single Over-the-Top operational amplifier with outstanding precision over a 0V to 76V input common-mode voltage range. It incorporates multiple built-in fault tolerant features, resulting in no-compromise performance over wide operating supply and temperature ranges. Over-the-Top inputs provide true operation well beyond the V rail. The LT6015 functions normally with its inputs up to 76V above V-, independent of whether V+ is 3V or 50V. Input offset voltage is 80μV max, input bias current is 5nA and low frequency noise is 0.5μVP-P … Fault protection modes guard against negative transients, reverse battery and other conditions… for applications where the amplifier is at the analog interface to another board, and for high-side and low-side current sensing.”
So there you have it. Op-amps encompass a wide array of performance tradeoffs, ranging from being very, very good in one or two parameters but just so-so in others (for example, speed versus power, or accuracy versus cost) to being pretty good in most areas but not outstanding in any one. Making the right decision is all about making choices among the various tradeoffs — and hey, isn't that what engineering is all about? And many times, spending a little more time (or money) for a better-fitting op-amp can save you effort in avoiding calibration, temperature compensation, and many other nasty real-world issues.
Have you ever been flustered or overwhelmed by too many choices for op-amps or some other components? Or do you like having this many parts and options to evaluate, so you can drill down to find one which is even just a slightly better match for your needs?