MIC864 MICREL [Micrel Semiconductor], MIC864 Datasheet - Page 7

• Manufacturer Part Number: MIC864
• Description: Dual 350kHz Rail-to-Rail Operational Amplifier
• Manufacturer: MICREL [Micrel Semiconductor]

Functional Description
The MIC864 is a dual-operational amplifier with an input
range 0.2V greater than the supply rails and an output
range to within 15mV of the supply rails (100kΩ load).
The MIC864 can be operated from a single from 2.5V to
5.5V supply or a dual ±1.25V to ±2.75V supply. It
features a low 33µA quiescent current per channel with
a gain bandwidth product of 350kHz.
Compared with other operational amplifiers in its class,
the MIC864 offers dependable CMRR and PSRR. This is
achieved through transconductance normalization, which
ensures consistent performance across the entire input
voltage range. This feature eliminates a region of the
input voltage range where some earlier operational
amplifiers were subject to degraded CMRR and PSRR.
Input Stage
The MIC864 uses parallel NFET and PFET differential
input transistor pairs for a common-mode input voltage
range beyond the supply rails. When input voltages are
high, the NFET differential input pair operates. When
input voltages are low, the PFET differential input pair
operates.
Functional Diagram
Micrel, Inc.
March 2012
MIC864 Block Diagram
7
Transconductance Normalization
Hand-off between the NFET and PFET differential pairs
is managed by the transconductance normalization
circuit block. As the common-mode input voltage
transitions between high and low voltages, this circuit
block ensures smooth, consistent, and continuous
operation.
Class AB Output Stage
Low output impedance is achieved by driving the
common-emitter output stage with a class AB control
circuit. In contrast with the common collector output
stages of earlier operational amplifiers, this allows an
output range very close to the supply rails.
M9999-032612-A
MIC864