By Jim Harrison
Our Product of the Month for October is one of the most useful devices any engineer can have — a very high-performance amplifier. The LT6018 op-amp from Linear Technology has numerous great specifications. The amp will be excellent for precision signal processing, data acquisition, and professional audio.
This op-amp has two considerable advantages. First, an op-amp with great specs allow an EE to do things more easily and more reliably. You don’t have to worry about the offset drift, the gain, or almost anything else — they are rock solid. And second, great amps allow the EE to do things they could not even do before.
The chip’s input noise voltage over 0.1 Hz to 10 Hz is just 0.03 µVp-p, and input noise voltage density at 1 KHz is 1.2 nV/√Hz. These figures are just about the best you can get and make the part well suited for signal conditioning for a precision A/D used for IoT sensor input applications.
But there’s more. Input offset voltage is typically only ±7 µV and over-temperature is just ±75 µV. Total harmonic distortion at RL = 600 Ω, f = 10 kHz is –104 dB. Open-loop gain is typically 142 dB, enabling the part to achieve linearity better than 1 ppm. The common-mode rejection ratio (CMRR) is a minimum of 120 dB (133 dB typical) and the power supply rejection ratio (PSRR) is 128 dB minimum. Input bias current is 150 na maximum at room temperature. As precise as it is, it still yields a pretty fast 11-MHz gain-bandwidth product and slew rate is up to 30 V/µs.
The IC can use a supply voltage of up to 36 V. Supply current is 9 mA maximum over –40°C to 85°C. In low-power shutdown, supply current is 6.2 µA. The LT6018 comes in –40°C to 85°C or –40°C to 125°C temperature ranges and in plastic SO or DFN packages. Both packages have a metal plate to help get the heat out and keep a stable internal temperature.
To me, these specs mean it could be our standard amp — we could use it everywhere. However, it’s not the low-power champion, and you will have to come up with $3.25 ea/1,000 to buy the LT6018. Still, you can’t live without this one.
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