ISL28134 Datasheet, PDF (16/20 Pages) Intersil Corporation – 5V Ultra Low Noise, Zero Drift Rail-to-Rail Precision Op Amp

ISL28134
In addition to the high gain and bandwidth, it is important that
the amplifier have low V_OS and temperature drift along with a
low input noise voltage. For example, an amplifier with 100µV
offset voltage and 0.5uV/°C offset drift configured in a closed loop
gain of 10,000V/V would produce an output error of 1V and a
5mV/°C temperature dependent error. Unless offset trimming and
temperature compensation techniques are used, this error makes it
difficult to resolve the input voltages needed in the precision
application.
The ISL28134 features a low V_OS of ±4µV max and a very stable
10nV/°C max temperature drift, which produces an output error of
only ±40mV and a temperature error of 0.1mV/°C. With an ultra
low input noise of 210nV_P-P (0.1Hz to 10Hz) and no 1/f corner
frequency, the ISL28134 is capable of amplifying signals in the µV
range with high accuracy. For even further DC precision, some
feedback filtering C_F (see Figure 49) to reduce the noise can be
implemented as a total signal stage amplifier. As a method of best
practice, the ISL28134 should be impedance matched at the two
input terminals. A balancing capacitor of the same value at the
non-inverting terminal will result in the amplifier input impedances
tracking across frequency.
100Ω
C_F
1MΩ
+2.5V
100Ω
V_IN
1MΩ
-
+
C_F
-2.5V
A_CL = 10kV/V
V_OUT
R_L
FIGURE 49. HIGH GAIN, PRECISION DC-COUPLED AMPLIFIER
16
FN6957.1
June 8, 2011