OPA3832_07 Datasheet, PDF (18/32 Pages) Burr-Brown (TI) – Triple, Low-Power, High-Speed, Fixed-Gain Operational Amplifier

OPA3832
SBOS370 – DECEMBER 2006
www.ti.com
APPLICATION INFORMATION
WIDEBAND VOLTAGE-FEEDBACK
OPERATION
The OPA3832 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
OPA3832 is compensated to provide stable
operation with a wide range of resistive loads.
Figure 46 shows the ac-coupled, gain of +2V/V
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 46, 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. This parallel combination equals the dc
resistance at the inverting input R_F), reducing the dc
output offset resulting from input bias current.
V_S = +5V
6.8mF
+
505W
0.1mF
0.1mF
2V
V_IN
66.7W 332W
1/3
OPA3832
400W
+2V
400W
V_OUT
R_L
150W
+2V
Figure 46. AC-Coupled, G = +2, +5V
Single-Supply Specification and Test Circuit
Figure 47 shows the ac-coupled, gain of +2V/V
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
ground. Voltage swings reported in the Electrical
Characteristics are taken directly at the input and
output pins. For the circuit of Figure 47, 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. This parallel combination equals the dc
resistance at the inverting input R_F), reducing the dc
output offset arising from input bias current.
V_S = +3.3V
6.8mF
+
1.13kW
0.1mF
0.1mF _+0.75V
V_IN
66.5W 255W
1/3
OPA3832
+0.75
400W
400W
V_OUT
R_L
150W
0.75V
Figure 47. AC-Coupled, G = +2, +3.3V
Single-Supply Specification and Test Circuit
Figure 48 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 48, the total
effective load will be 150Ω || 800Ω. Two optional
components are included in Figure 48. 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 configuration 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 printed circuit
board (PCB) board layouts, this optional capacitor
will typically improve the 2nd-harmonic distortion
performance by 3dB to 6dB.
18
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