XR1008 Datasheet, PDF (10/17 Pages) Exar Corporation – 0.5mA, 75MHz Rail-to-Rail Amplifiers

XR1008, XR2008
Application Information
General Description
The XR1008 family are a single supply, general purpose,
voltage-feedback ampli ers fabricated on a complementary
bipolar process. The XR1008 offers 75MHz unity gain
bandwidth, 50V/μs slew rate, and only 505μA supply current.
It features a rail-to-rail output stage and is unity gain stable.
Figures 1, 2, and 3 illustrate typical circuit con gurations for
non-inverting, inverting, and unity gain topologies for dual
supply applications. They show the recommended bypass
capacitor values and overall closed loop gain equations.
Figure 4 shows the typical non-inverting gain circuit for
single supply applications.
The common mode input range extends to 300mV below
ground in single supply operation. Exceeding these values
will not cause phase reversal. However, if the input voltage
exceeds the rails by more than 0.5V, the input ESD devices
will begin to conduct.
The design uses a Darlington output stage. The output
stage is short circuit protected and offers “soft” saturation
protection that improves recovery time.
+Vs
6.8μF
+Vs
6.8μF
Input
+
0.1μF
-
0.1μF
Output
RL
6.8μF
-Vs
G=1
Figure 3: Unity Gain Circuit
+V_s
6.8μF
+
In
0.1μF
+
Out
-
R_f
R_g
Input
+
0.1μF
-
0.1μF
Rf
Output
RL
Rg
6.8μF
-Vs
G = 1 + (Rf/Rg)
Figure 1: Typical Non-Inverting Gain Circuit
+Vs
6.8μF
Figure 4: Single Supply Non-Inverting Gain Circuit
For optimum response at a gain of +2, a feedback resistor
of 1kΩ is recommended. Figure 5 illustrates the XR1008
frequency response with both 1kΩ and 2kΩ feedback
resistors.
G=2
R_L = 1kΩ
R_f = 2kΩ
R_f = 1kΩ
Input
R1
+
Rg
-
0.1μF
0.1μF
Rf
Output
RL
6.8μF
-Vs
G = - (Rf/Rg)
For optimum input offset
voltage set R1 = Rf || Rg
Figure 2: Typical Inverting Gain Circuit
© 2014 Exar Corporation
10 / 17
0.1
1
10
100
Frequency (MHz)
Figure 5: Frequency Response vs. R_f
exar.com/XR1008
Rev 1B