OPA2832 Datasheet, PDF (20/37 Pages) National Semiconductor (TI) – Dual, Low-Power, High-Speed, Fixed-Gain Operational Amplifier

OPA2832
SBOS327C – FEBRUARY 2005 – REVISED AUGUST 2008 ............................................................................................................................................. www.ti.com
APPLICATIONS INFORMATION
WIDEBAND VOLTAGE-FEEDBACK
OPERATION
The OPA2832 is a unity-gain stable, very high-speed
voltage-feedback op amp designed for single-supply
operation (+3V to +11V). The input stage supports
input voltages below ground and to within 1.7V of the
positive supply. The complementary common-emitter
output stage provides an output swing to within 25mV
of ground and the positive supply. The OPA2832 is
compensated to provide stable operation with a wide
range of resistive loads.
Figure 61 shows the AC-coupled, gain of +2
configuration used for the +5V Specifications and
Typical Characteristic Curves. For test purposes, the
input impedance is set to 50Ω with the 66.7Ω resistor
to ground in parallel with the 200Ω bias network.
Voltage swings reported in the Electrical
Characteristics are taken directly at the input and
output pins. For the circuit of Figure 61, the total
effective load on the output at high frequencies is
150Ω || 800Ω. The 332Ω and 505Ω resistors at the
noninverting input provide the common-mode bias
voltage. Their parallel combination equals the DC
resistance at the inverting input R_F), reducing the DC
output offset due to input bias current.
ground. Voltage swings reported in the Electrical
Characteristics are taken directly at the input and
output pins. For the circuit of Figure 62, the total
effective load on the output at high frequencies is
150Ω || 800Ω. The 255Ω and 1.13kΩ resistors at the
noninverting input provide the common-mode bias
voltage. Their parallel combination equals the DC
resistance at the inverting input R_F), reducing the DC
output offset due to input bias current.
V_S = +3.3V
6.8µF
+
1.13kΩ
0.1µF
0.1µF _+0.75V
V_IN
66.5Ω 255Ω
1/2
OPA2832
+0.75
400Ω
400Ω
V_OUT
R_L
150Ω
0.75V
Figure 62. AC-Coupled, G = +2, +3V Single-Supply
Specification and Test Circuit
V_S = +5V
6.8µF
+
505Ω
0.1µF
0.1µF
2V
V_IN
66.7Ω 332Ω
1/2
OPA2832
+V_S/2
400Ω
400Ω
V_OUT
R_L
150Ω
+V_S
2
Figure 61. AC-Coupled, G = +2, +5V Single-Supply
Specification and Test Circuit
Figure 62 shows the AC-coupled, gain of +2
configuration used for the +3.3V Specifications and
Typical Characteristic Curves. For test purposes, the
input impedance is set to 66.5Ω with a resistor to
Figure 63 shows the DC-coupled, gain of +2, dual
power-supply circuit configuration used as the basis
of the ±5V Electrical Characteristics and Typical
Characteristics. For test purposes, the input
impedance is set to 50Ω with a resistor to ground and
the output impedance is set to 150Ω with a series
output resistor. Voltage swings reported in the
specifications are taken directly at the input and
output pins. For the circuit of Figure 63, the total
effective load will be 150Ω || 800Ω. Two optional
components are included in Figure 63. An additional
resistor (175Ω) is included in series with the
noninverting input. Combined with the 25Ω DC
source resistance looking back towards the signal
generator, this gives an input bias current cancelling
resistance that matches the 200Ω source resistance
seen at the inverting input (see the DC Accuracy and
Offset Control section). In addition to the usual
power-supply decoupling capacitors to ground, a
0.01µF capacitor is included between the two
power-supply pins. In practical PC board layouts, this
optional capacitor will typically improve the
2nd-harmonic distortion performance by 3dB to 6dB.
20
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