Datasheet

10Maxim Integrated
MAX44259/MAX44260/MAX44261/MAX44263
1.8V, 15MHz Low-Offset,
Low-Power, Rail-to-Rail I/O Op Amps
Figure 1. Comparing the Input Structure of the MAX44260 to Standard Op-Amp Inputs
Figure 2. Crossover Distortion of Typical Amplifiers
Detailed Description
The MAX44259/MAX44260/MAX44261/MAX44263 are
high-speed low-power op amps ideal for signal process-
ing applications due to the device’s high precision and
low-noise CMOS inputs. The devices self-calibrate on
power-up to eliminate effects of temperature and power-
supply variation.
The MAX44260 also features a low-power shutdown
mode that greatly reduces quiescent current while the
device is not operational and recovers in 30µs.
The MAX44261 features a user-selectable self-calibration
input that shuts down the device and allows it to be reca-
librated at any time. The calibration routine takes 10ms.
Crossover Distortion
These op amps feature a low-noise integrated charge
pump that creates an internal voltage rail 1V above
V
DD,
which is used to power the input differential
pair of PMOS transistors as shown in Figure 1. Such
a unique architecture eliminates crossover distor-
tion common in traditional CMOS input architecture
(Figure 2), especially when used in a noninverting
configuration, such as for Sallen-Key filters.
The charge pump’s operating frequency lies well above
the unity-gain frequency of the amplifier. Thanks to its high-
frequency operation and ultra-quiet circuitry, the charge
pump generates little noise, does not require external
components, and is entirely transparent to the user.
STANDARD INPUT STRUCTURE
MAX44260 INPUTS STRUCTURE
INTERNAL
CHARGE
PUMP
CROSSOVER
DISTORTION
MAX44261
TIME
AMPLIFIER OUTPUT