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LTC6240 gain bandwidth product

Category: Datasheet/Specs
Product Number: LTC6240

The spec sheet of this amplifier (https://www.analog.com/en/search.html?query=LTC6240) states in its title and in the tables that this OpAmp has a Gain Bandwidth product (GBW) of 18 MHz (typically) and 13 MHz minimum.

However:

- Why is that specified under the condition "Frequency = 20KHz"? Is the GBW dependent on frequency? Which frequency? And how?

- The graph in the middle of page 15 shows the open loop gain vs. frequency of the OpAmp, where the trace crosses the 0 dB line at 5 MHz (or 3 MHz for a 3 V total supply), that is nowhere near 18 MHz.
The simulation model concurs. In open loop the result is comparable to this graph, albeit the GBW is 5 MHz irrespective of supply voltage. In closed loop at various gains the traces also cross the 0 dB line at or near 5 MHz.

What's going on?

Parents
  • Hi LucMeson:   Linear Technology specified the Gain-Bandwidth-Product, being the product of the gain and the frequency at some specified frequency.  The true acronym should be GBWP but this was truncated to GBW.  The intent was to truly indicate the magnitude of the gain at mid-band frequencies.  To get a complete picture as to the frequency response of any amplifier, it is necessary to consult the Gain/Phase plot. 

Reply
  • Hi LucMeson:   Linear Technology specified the Gain-Bandwidth-Product, being the product of the gain and the frequency at some specified frequency.  The true acronym should be GBWP but this was truncated to GBW.  The intent was to truly indicate the magnitude of the gain at mid-band frequencies.  To get a complete picture as to the frequency response of any amplifier, it is necessary to consult the Gain/Phase plot. 

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