|
|
PDF AD605 Data sheet ( Hoja de datos )
| Número de pieza | AD605 | |
| Descripción | Dual/ Low Noise/ Single-Supply Variable Gain Amplifier | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de AD605 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
|
No Preview Available !
www.DataSheet4U.com
a
FEATURES
Two Independent Linear-in-dB Channels
Input Noise at Maximum Gain: 1.8 nV/√Hz, 2.7 pA/√Hz
Bandwidth: 40 MHz (–3 dB)
Differential Input
Absolute Gain Range Programmable:
–14 dB to +34 dB (FBK Shorted to OUT) Through
0 dB to +48 dB (FBK Open)
Variable Gain Scaling: 20 dB/V Through 40 dB/V
Stable Gain with Temperature and Supply Variations
Single-Ended Unipolar Gain Control
Output Common-Mode Independently Set
Power Shutdown at Lower End of Gain Control
Single 5 V Supply
Low Power: 90 mW/Channel
Drives A/D Converters Directly
APPLICATIONS
Ultrasound and Sonar Time-Gain Control
High Performance AGC Systems
Signal Measurement
Dual, Low Noise, Single-Supply
Variable Gain Amplifier
AD605
FUNCTIONAL BLOCK DIAGRAM
VGN
VREF
GAIN
CONTROL
AND
SCALING
PRECISION PASSIVE
INPUT ATTENUATOR
+IN DIFFERENTIAL
ATTENUATOR
–IN 0 TO –48.4dB
FIXED GAIN
AMPLIFIER
+34.4dB
OUT
FBK
VOCM
AD605
GENERAL DESCRIPTION
The AD605 is a low noise, accurate, dual channel, linear-in-dB
variable gain amplifier, which is optimized for any application
requiring high performance, wide bandwidth variable gain con-
trol. Operating from a single 5 V supply, the AD605 provides
differential inputs and unipolar gain control for ease of use.
Added flexibility is achieved with a user-determined gain range
and an external reference input which provides user-determined
gain scaling (dB/V).
The high performance linear-in-dB response of the AD605 is
achieved with the differential input, single supply, exponential
amplifier (DSX-AMP) architecture. Each of the DSX-AMPs
comprise a variable attenuator of 0 dB to –48.4 dB followed by
a high speed fixed gain amplifier. The attenuator is based on a
7-stage R-1.5R ladder network. The attenuation between tap
points is 6.908 dB, and 48.360 dB for the entire ladder network.
The DSX-AMP architecture results in 1.8 nV/√Hz input noise
spectral density and will accept a ± 2.0 V input signal when
VOCM is biased at VP/2.
Each independent channel of the AD605 provides a gain range
of 48 dB which can be optimized for the application. Gain
ranges between –14 dB to +34 dB and 0 dB to +48 dB can be
selected by a single resistor between pins FBK and OUT. The
lower and upper gain ranges are determined by shorting pin
FBK to OUT, or leaving pin FBK unconnected, respectively.
The two channels of the AD605 can be cascaded to provide 96
dB of very accurate gain range in a monolithic package.
The gain control interface provides an input resistance of approxi-
mately 2 MΩ and scale factors from 20 dB/V to 30 dB/V for a
VREF input voltage of 2.5 V to 1.67 V, respectively. Note that
scale factors up to 40 dB/V are achievable with reduced accu-
racy for scales above 30 dB/V. The gain scales linearly in dB
with control voltages (VGN) of 0.4 V to 2.4 V for the 20 dB/V
scale and 0.20 V to 1.20 V for the 40 dB/V scale. When VGN
is <50 mV the amplifier is powered down to draw 1.9 mA.
Under normal operation, the quiescent supply current of each
amplifier channel is only 18 mA.
The AD605 is available in 16-lead PDIP and SOIC, and is
guaranteed for operation over the –40°C to +85°C tempera-
ture range.
REV. C
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
www.analog.com
Fax: 781/326-8703 © 2004 Analog Devices, Inc. All rights reserved.
1 page  
www.DataSheet4U.com
60
40
20
0
–20
–40
VGN = 2.9V (FBK = OPEN)
VGN = 2.9V (FBK = SHORT)
VGN = 1.5V (FBK = OPEN)
VGN = 1.5V (FBK = SHORT)
VGN = 0.1V (FBK = OPEN)
VGN = 0.1V (FBK = SHORT)
VGN = 0.0V
–60
100k
1M 10M
FREQUENCY (Hz)
100M
TPC 10. AC Response
1000
100
10
1
0.1 0.5 0.9 1.3 1.7 2.1 2.5 2.9
VGN (V)
TPC 13. Input Referred Noise vs.
VGN
100
VGN = 2.9V
10
1 RSOURCE ALONE
0.1
1
10 100
Frequency (⍀)
1k
TPC 16. Input Referred Noise vs.
RSOURCE
2.525
VOCM = 2.50V
2.520
–40 C
2.515
2.510
2.505
+25 C
2.500
2.495
2.490
+85 C
2.485
2.480
2.475
0
0.5 1.0 1.5 2.0 2.5 3.0
VGN (V)
TPC 11. Output Offset vs. VGN
AD605
130
125
+85 C
120
115 +25 C
110
105 –40 C
100
95
90
0 0.5 1.0 1.5 2.0 2.5 3.0
VGN (V)
TPC 12. Output Referred Noise vs.
VGN
2.00
VGN = 2.9V
1.95
1.90
1.85
1.80
1.75
1.70
1.65
1.60
–40 –20
0 20 40 60
TEMPERATURE ( C)
80 90
TPC 14. Input Referred Noise vs.
Temperature
1.90
1.85
VGN = 2.9V
1.80
1.75
1.70
1.65
1.60
100k
1M
FREQUENCY (Hz)
10M
TPC 15. Input Referred Noise vs.
Frequency
30
VGN = 2.9V
25
20
15
10
5
1 10 100 1k
RSOURCE (⍀)
TPC 17. Noise TPC vs. RSOURCE
60
RS = 50⍀
50
40
30
20
10
0
0.1 0.5 0.9 1.3 1.7 2.1 2.5 2.9
VGN (V)
TPC 18. Noise TPC vs. VGN
REV. C
–5–
5 Page 
www.DataSheet4U.com
Two other easy combinations are possible to provide a gain
range of –14 dB to +82.8 dB: (1) make R1 a short and R2 an
open; or (2) make R1 an open and R2 a short. The bandwidth
for both of these cases will be dominated by the channel that is
set to the higher gain and will be about 8 MHz. From a noise
standpoint, the second choice is the best since by increasing the
gain of the first amplifier, the second amplifier’s noise will have
less of an impact on the total output noise. One further observa-
tion regarding noise is that by increasing the gain the output
noise will increase proportionally; therefore, there is no increase
in signal-to-noise ratio. It will actually stay fixed.
It should be noted that by selecting the appropriate values of R1
and R2, any gain range between –28 dB to +68.8 dB and 0 dB
to +96.8 dB can be achieved with the circuit in Figure 5. When
using any value other than shorts and opens for R1 and R2, the
final value of the gain range will depend on external resistors
matching on-chip resistors. Since the internal resistors can vary
by as much as ± 20%, the actual values for a particular gain have
to be determined empirically. Note that the two channels within
one part will match quite well; therefore, R1 will track R2 in
Figure 5.
C3 is not required since the common-mode voltage at Pin OUT1
should be identical to the one at Pins +IN2 and –IN2. However,
since only 1 mV of offset at the output of the first DSX will
introduce an offset of 53 mV when the second DSX is set to the
maximum gain of the lowest gain range (34.4 dB), and 263 mV
when set to the maximum gain of the highest gain range (48.4 dB),
it is important to include ac coupling to get the maximum dy-
namic range at the output of the cascaded amplifiers. C5 is
necessary if the output signal needs to be referenced to any
common-mode level other than half of the supply as is provided
by Pin OUT2.
Figure 6 shows the gain versus VGN for the circuit in Figure 5
at 1 MHz and the lowest gain range (–14 dB to +34.4 dB). Note
that the gain scaling is 40 dB/V, double the 20 dB/V of an indi-
vidual DSX; this is the result of the parallel connection of the
gain control inputs, VGN1 and VGN2. One could of course
also sequentially increase the gain by first increasing the gain of
Channel 1 and then Channel 2. In that case VGN1 and VGN2
will have to be driven from separate voltage sources, for instance
two separate DACs. Figure 7 shows the gain error of Figure 5.
AD605
80
70
f = 1MHz
60
50
40
30
20
10
0
–10
–20
–30
–40
0.1
0.5
0.9
THEORETICAL
ACTUAL
1.3 1.7 2.1 2.5 2.9
VGN (V)
Figure 6. Gain vs. VGN for the Circuit in Figure 5
4
f = 1MHz
3
2
1
0
–1
–2
–3
–4
0.2 0.7 1.2 1.7 2.2 2.7
VGN (V)
Figure 7. Gain Error vs. VGN for the Circuit in Figure 5
REV. C
–11–
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet AD605.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| AD600 | Dual/ Low Noise/ Wideband Variable Gain Amplifiers | Analog Devices |
| AD602 | Dual/ Low Noise/ Wideband Variable Gain Amplifiers | Analog Devices |
| AD6025GP | Fan |  ADDA |
| AD603 | Variable Gain Amplifier | Analog Devices |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |