OPA320-Q1 Datasheet, PDF (20/34 Pages) Texas Instruments – Precision, 20-MHz, 0.9-pA, Low-Noise, RRIO, CMOS Operational Amplifier

OPA320-Q1, OPA2320-Q1
SLOS884A – SEPTEMBER 2014 – REVISED DECEMBER 2016
www.ti.com
8.2.3 Driving ADCs
The OPAx320-Q1 device series op amps are well-suited for driving sampling analog-to-digital converters (ADCs)
with sampling speeds up to 1 MSPS. The zero-crossover distortion input stage topology allows the OPAx320-Q1
device to drive ADCs without degradation of differential linearity and THD.
The OPAx320-Q1 device can be used to buffer the ADC switched input capacitance and resulting charge
injection while providing signal gain. Figure 42 shows the OPAx320-Q1 device configured to drive the ADS8326.
5V
50 kΩ
(2.5 V)
8
REF1004-2.5
4
5V
R1
100 kΩ
R_(G)
R2
25 kΩ
5V
½
OPA2320-Q1
R3
25 kΩ
R4
100 kΩ
½
OPA2320-Q1
G = 5 + ^{200 kΩ}
R_(G)
V_O
R_(L)
10 kΩ
Figure 41. Two Op-Amp Instrumentation Amplifier With Improved High-Frequency Common-Mode
Rejection
5V
V_I
0 to 4.096 V
C1
100 nF
V_(V+)
OPA320-Q1
V_(V–)
R1⁽¹⁾
100 Ω
C3⁽¹⁾
1 nF
–5 V
R2
50 kΩ
Optional⁽²⁾
SD1
BAS40
C2
100 nF
5V
REF3240
4.096V
5V
+INx
–INx
ADS8326
16-Bit
250kSPS
REF IN
C4
100 nF
(1) Suggested value; may require adjustment based on specific application.
(2) Single-supply applications lose a small number of ADC codes near ground as a result of op amp output swing limitation. If a negative
power supply is available, this simple circuit creates a –0.3-V supply to allow output swing to true ground potential.
Figure 42. Driving the ADS8326
20
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