OPA2830_08 Datasheet, PDF (28/41 Pages) Burr-Brown (TI) – Dual, Low-Power, Single-Supply, Wideband OPERATIONAL AMPLIFIER

OPA2830
SBOS309C – AUGUST 2004 – REVISED MARCH 2006
+V_S
+5V
374Ω
2.2nF 2.2nF
1/2
OPA2830
750Ω
2kΩ
1µF
V_I
V_S/2
V_O
2kΩ
750Ω
2.2nF 2.2nF
1/2
OPA2830
374Ω
Figure 81. 138kHz, 2nd-Order, High-Pass Filter
Results showing the frequency response for the
circuit of Figure 81 is shown in Figure 82.
3
0
−3
−6
−9
−12
0.01
0.1
1
10
Frequency (MHz)
Figure 82. Frequency Response for the Filter of
Figure 81
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compliance voltage other than ground for operation,
the appropriate voltage level may be applied to the
noninverting input of the OPA2830. The DC gain for
this circuit is equal to R_F. At high frequencies, the
DAC output capacitance (C_D in Figure 83) will
produce a zero in the noise gain for the OPA2830
that may cause peaking in the closed-loop frequency
response. C_F is added across R_F to compensate for
this noise gain peaking. To achieve a flat
transimpedance frequency response, the pole in
each feedback network should be set to:
Ǹ ¹
2pR_FC_F
+
GBP
4pR_FC_D
which will give a cutoff frequency f_–3dB of
approximately:
Ǹ f_*3dB +
GBP
2pR_FC_D
+5V
High−Speed
DAC
I_O
2.5kΩ
C_D1
2.5kΩ
1/2
OPA2830
R_F1
C_F1
R_F2
V_O = I_O R_F
C_D2
C_F2
− I_O
+5V
2.5kΩ
1/2
OPA2830
−V_O = −I_O R_F
2.5kΩ
GBP →Gain Bandwidth
Product (Hz) for the OPA2830
HIGH-PERFORMANCE DAC
TRANSIMPEDANCE AMPLIFIER
High-frequency video Digital-to-Analog Converters
(DACs) can sometimes benefit from a low distortion
output amplifier to retain their SFDR performance
into real-world loads. Figure 83 shows a differential
output drive implementation. The diagram shows the
signal output current(s) connected into the virtual
ground summing junction(s) of the OPA2830, which
is set up as a transimpedance stage or I-V converter.
If the DAC requires that its outputs terminate to a
Figure 83. High-Speed DAC—Differential
Transimpedance Amplifier
28
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