Maxim > Design Support > Technical Documents > Application Notes > Amplifier and Comparator Circuits > APP 4295
Maxim > Design Support > Technical Documents > Application Notes > Automatic Test Equipment (ATE) > APP 4295
Maxim > Design Support > Technical Documents > Application Notes > Automotive > APP 4295
Keywords: linear amplifier response, feedback distortion, perfect-diode comparator, slew-rate, Op Amp,
frequency response, bias, gain, low pass filters, signal bandwidth
APPLICATION NOTE 4295
Small-Signal Bandwidth in a Big-Band Era
By: Bill Laumeister, Strategic Applications Engineer
Jun 24, 2011
Abstract: The popular music of several decades ago required many instruments, hence the name "big
band era." Today, bandwidth increase is again a sign of the times. The explosion of Internet usage,
network-capable cellular phones (3G, 4G, LTE, and Wi-Fi®), music players, and digital video cameras
has expanded consumers' expectations for bandwidth. We are on the cusp of wholesale data transfer to
all portable devices. Bandwidth has become king, and we are therefore again in a "big bandwidth era."
So, why discuss small-signal bandwidth?
A similar version of this article appeared in the April 8, 2011 issue of Planet Analog magazine.
Many operational amplifiers (op amps) include a specification of small-signal bandwidth in their data
sheets. (All op amps have a "sweet spot" for better bandwidth, even if it is not mentioned in the data
sheet.) This specification is typically based on a signal amplitude limited to about one-tenth of a volt, and
at first glance seems primarily for use in comparison and for "boasting rights" with other op-amp
companies.
Some applications, however, can take advantage of the small-signal bandwidth, which can be many
times greater than the large-signal bandwidth for an op amp. For example, the MAX4104 op amp has a
small-signal bandwidth (0.1V or less) of 625MHz, and a large-signal bandwidth (2V peak-to-peak) of
11MHz. Most applications make use of the large-signal bandwidth. Small-signal bandwidth is high
because the op amp is operating in its midrange sweet spot (Figure 1).
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