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OPA1656: High-Performance CMOS Audio Op Amp

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#61
tomchr said:
I especially enjoyed the change National made from LM (everything) to LME (audio), LMP (precision), LMX (frequency synthesizers), LMK (clocking - which somehow is different from frequency synthesizers), LMV (general purpose opamps), etc. I think it was a good move, even if the transition was a bit rough.

Tom
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There were LH right? Hybrid. M is monolithic right? And then LMH monolithic high speed.
 
#72
My good friend Carl put them on a DIP adapter for me, bass extends low, imaging and detail is very good. One of the best for sure, I like.
 

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#74
HpW said:
Will there also a single chip as OPA1655 available?

And how those compete against the LME49720 😀

Hp
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johnc124 said:
Last week TI put a preliminary datasheet online for the OPA1656, a low noise, very low distortion op amp targeting audio applications and fabricated in a CMOS process.

http://www.ti.com/product/OPA1656

I just checked and the sample button for the prototype devices is now active:

http://www.ti.com/product/OPA1656/samplebuy

I started this project in 2017 with the designer of the OPA1622, and although I had a change in my role at TI before the device was released to market, I'm still very proud of what was accomplished. The goals of the project were fairly straightforward:

1. Start with the OPA1688 architecture which gives very good distortion performance, even with low-impedance loads. Beef up the output

A quick snapshot of the OPA1656 performance specs:
  • 2.9nV/rtHz broadband voltage noise
  • 6 fa/rtHz broadband current noise
  • -131 dB THD+N at 1kHz, 600 ohm load, 3.5Vrms signal, 80-kHz measurement bandwidth
  • 53 MHz gain bandwidth product, 24V/us slew rate
  • >100mA output current
  • 4.0mA typical supply current, 4.5mA max

I'm looking forward to seeing what people think of the device, and hopefully it finds its way into a few projects on here!
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Any comment on single opamp ???
 
#76
tomchr said:
±20 V, 100 mA, THD ~-130 dB @ 2 kΩ load. $1-something @ QTY 1k. What's not to like? 🙂

It looks like this one has the phase kink (lead/lag compensation) towards UGBW as well. That's the only drawback I can see. It makes it a little harder to use this opamp in a composite amp. That's not a show stopper, though. I'll just have to work harder to get around it.

Nice work John (et al.)

Tom
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Sorry, I am new to these. I wanted to know why phase kink towards UGBW is a drawback ?
 
#80
That's good to know; I suspected as much when I saw the 100 mA drive current capability. But I was concerned because the datasheet doesn't show any graphs for distortion with loads < 600Ω, and shows an application note depicting the use of an additional BUF 634 for driving headphones---perhaps this is only necessary for 8/16Ω loads? Also, I noticed that the distortion rises somewhat @ 10-20K Hz when driving the 600Ω load as compared to the 2KΩ load. Is it then good to go for 32Ω phones? If so, it's a pretty amazing feat for a 8-pin SOIC chip, indeed!
 
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