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www.fairchildsemi.com
Features
Very low noise
Spectral noise density – 3.8 nV/
Hz
1/F noise corner frequency – 2.7 Hz
Very low VOS drift – 0.3
m
V/Mo; 0.3
m
V/C
High gain – 500 V/mV
High output drive capability –
±
10V into 1K load
High slew rate – 2.7 V/
m
S
Wide gain bandwidth product – 8 MHz
High common mode rejection ratio – 104 dB
Low input offset voltage – 75
m
V
Low frequency noise – 0.08
m
V
p-p
(0.1 Hz to 10 Hz)
Low input offset current – 2.5 nA
Industry standard pinout
8-Lead DIP
Description
The RC4227, a dual version of the OP-27, is designed for
instrumentation grade signal conditioning where low noise
(both spectral density and burst), wide bandwidth, and high
slew rate are required along with low input offset voltage,
low input offset temperature coefficient, and low input bias
currents. These features are all available in a device which is
internally compensated for excellent phase margin (70) in a
unity gain configuration. Digital nulling techniques
performed at wafer sort make it feasible to guarantee temper-
ature stable input offset voltages as low as 75
m
V max.
Input bias current cancellation techniques are used to obtain
±
45 nA max. input bias currents.
In addition to providing superior performance for audio fre-
quency range applications, the RC4227 design uniquely
addresses the needs of the instrumentation designer.
Power supply rejection and common mode rejection are both
in excess of 100 dB. A phase margin of 70 at unity gain
guards against peaking (and ringing) in low gain feedback
circuits. Stable operation can be obtained with capacitive
loads up to 2000 pF
1
. The drift performance is, in fact, so
good that the system designer must be cautioned that stray
thermoelectric voltages generated by dissimilar metals at the
contacts to the input terminals are enough to degrade its per-
formance. For this reason it is also important to keep both
input terminals at the same relative temperature.
The performance of the RC4227 is achieved using precision
amplifier design techniques coupled with a process that
combines nitride transistors and capacitors with precision
thin-film resistors. The die size savings of nitride capacitors
and thin film resistors allow the RC4227 to be offered in an
8-pin mini-dip package and fit the industry standard dual op
amp pinout.
Note:
1. By decoupling the load capacitance with a series resistor
of 50
W
or more, load capacitances larger than 2000 pF can
be accommodated.
Block Diagram
A
B
65-3468-01
Output A
–Input A
+Input A
–VS
+VS
Output B
–Input B
+Input B
RC4227
Dual Prec ision Operational Amplifier
Rev. 1.0.0