I was looking at using the OPA860 for a voltage controlled load. Reading in the OPA860 datasheet it says:
The OPA860 combines a high-performance buffer with a transconductance
section. This transconductance section is discussed in the OTA The
buffer section of the OPA860 is an 1600MHz, (Operational
Transconductance Amplifier) section of 4000V/μs closed-loop buffer
that can be used as a this data sheet. Over the years and depending on
the building block for AGC amplifiers, LED driver circuit, writer, the
OTA section of an op amp has been integrator for fast pulse, fast
control loop amplifiers, referred to as a Diamond Transistor, and
control amplifiers for capacitive sensors and Voltage-Controlled
Current source, Transconductor, active filters.
Are they achieving the transconductance with regular boring silicon tech (which is probably the case) or something else?
My main reason for asking the question is because its a cool part (low noise and transconductance), and because even though I suspect there is no secret sauce maybe there is, it also says ±1.2V differential input which I thought was interesting.
Best Answer
It's a particular complementary BJT circuit arrangement as so:
Which behaves similarly to transistor that does not have a Vbe offset and biasing issues, as explained in the link which @user3528438 also provided in a comment.
It's made with Burr-Brown/TI's high performance silicon analog IC process, not carbon-based.