OPA2652 Datasheet, PDF (11/23 Pages) Burr-Brown (TI) – Dual, 700MHz, Voltage-Feedback OPERATIONAL AMPLIFIER

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Differential ADC Driver
The circuit on the front page shows an OPA2652
driving the ADS807 analog-to-digital converter (ADC)
differentially, at a gain of +2V/V. The outputs are
AC-coupled to the converter to adjust for the
difference in supply voltages. The 133Ω resistors at
the noninverting inputs minimize DC offset errors.
The differential topology minimizes even-order
distortion products, such as second-harmonic
distortion.
Bandpass Filter
Figure 31 shows a single OPA2652 implementing a
sixth-order bandpass filter. This filter cascades two
second-order Sallen-Key sections with transmission
zeros, and a double real pole section. It has 0.3dB of
ripple, –3dB frequencies of 450kHz and 11MHz, and
–23dB frequencies of 315kHz and 16MHz. The
20.0Ω resistor isolates the first OPA2652 output from
capacitive loading. This configuration improves
stability with minimal impact on the filter response.
Figure 30 shows the nominal response simulated by
SPICE.
OPA2652
SBOS125A – JUNE 2000 – REVISED MAY 2006
0
-5
-10
-15
-20
-25
-30
-35
-40
10k
100k
1M
10M
Frequency (Hz)
100M
Figure 30. Nominal Filter Response
2.2nF
140W
2.10kW
V_IN
1.30kW
1.0nF
1.0nF
1% Resistors
5% Capacitors
+5V
1/2
OPA2652
V_OUT
143W
200W
100pF
2.7nF
100W
+5V
1/2
OPA2652
-5V
24.9W
-5V _24.9W
180pF
225W
158W
18pF
20.0W ^12pF
150pF
107W
Figure 31. Bandpass Filter
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