AD797BRZ-REEL Analog Devices Inc, AD797BRZ-REEL Datasheet - Page 17

• Manufacturer Part Number: AD797BRZ-REEL
• Description: IC,Operational Amplifier,SINGLE,BIPOLAR,SOP,8PIN,PLASTIC
• Manufacturer: Analog Devices Inc

Specifications of AD797BRZ-REEL

• Amplifier Type: General Purpose
• Number Of Circuits: 1
• Slew Rate: 20 V/µs
• Gain Bandwidth Product: 110MHz
• -3db Bandwidth: 8MHz
• Current - Input Bias: 250nA
• Voltage - Input Offset: 10µV
• Current - Supply: 8.2mA
• Current - Output / Channel: 50mA
• Voltage - Supply, Single/dual (±): ±5 V ~ 15 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Ultrasound/Sonar Imaging Preamp
The AD600 variable gain amplifier provides the time-controlled
gain (TCG) function necessary for very wide dynamic range
sonar and low frequency ultrasound applications. Under some
circumstances, it is necessary to buffer the input of the AD600
to preserve its low noise performance. To optimize dynamic
range, this buffer should have a maximum of 6 dB of gain. The
combination of low noise and low gain is difficult to achieve.
The input buffer circuit shown in Figure 50 provides 1 nV/√Hz
noise performance at a gain of 2 (dc to 1 MHz) by using
26.1 Ω resistors in its feedback path. Distortion is only −50 dBc
at 1 MHz for a 2 V p-p output level and drops rapidly to better
than −70 dBc at an output level of 200 mV p-p.
Amorphous (Photodiode) Detector
Large area photodiodes (C
detectors (amorphous Si) have optimum performance when used
in conjunction with amplifiers with very low voltage (rather than
very low current noise). Figure 51 shows the AD797 used with
an amorphous Si (C
for flatness using capacitor C
voltage noise amplified by the ac noise gain. The AD797’s excellent
input noise performance gives 27 μV rms total noise in a 1 MHz
bandwidth, as shown by Figure 52.
V
*USE THE POWER SUPPLY BYPASSING SHOWN IN FIGURE 35.
IN
26.1Ω
*USE THE POWER SUPPLY BYPASSING SHOWN IN FIGURE 35.
I
S
Figure 50. An Ultrasound Preamplifier Circuit
Figure 51. Amorphous Detector Preamp
C
1000pF
2
3
S
26.1Ω
S
AD797
= 1000 pF) detector. The response is adjusted
+V
–V
7
4
S
S
2
3
S
≥ 500 pF) and certain image
AD797
100Ω
L
, and the noise is dominated by
*
*
6
10kΩ
+V
–V
7
4
S
S
50pF
C
L
V
S
= ±6Vdc
*
6
*
AD600
*
*
V
OUT
V
OUT
Rev. H | Page 17 of 20
Professional Audio Signal Processing—DAC Buffers
The low noise and low distortion of the AD797 make it an ideal
choice for professional audio signal processing. An ideal I-to-V
converter for a current output DAC would simply be a resistor
to ground, were it not for the fact that most DACs do not operate
linearly with voltage on their output. Standard practice is to
operate an op amp as an I-to-V converter, creating a virtual
ground at its inverting input. Normally, clock energy and current
steps must be absorbed by the op amp output stage. However, in
the configuration shown in Figure 53, Capacitor C
frequency energy to ground while correctly reproducing the
desired output with extremely low THD and IMD.
–30
–40
–50
–60
–70
–80
100
*USE THE POWER SUPPLY BYPASSING SHOWN IN FIGURE 35.
AD1862
DAC
Figure 52. Total Integrated Voltage Noise and V
Figure 53. A Professional Audio DAC Buffer
–IN
+IN
1k
2000pF
Figure 54. Offset Null Configuration
C1
of Amorphous Detector Preamp
10k
2
3
–V
FREQUENCY (Hz)
V
AD797
2
3
4
OUT
82pF
S
C
AD797
F
1
+V
100k
7
S
3kΩ
+V
–V
20kΩ
5
7
4
S
S
100Ω
6
V
1M
OS
*
*
6
ADJUST
V
OUT
NOISE
10M
V
F
OUT
OUT
shunts high
100M
AD797
100
80
60
20
0
40