DataSheet.es    


PDF CLC5523IN Data sheet ( Hoja de datos )

Número de pieza CLC5523IN
Descripción Low-Power/ Variable Gain Amplifier
Fabricantes National Semiconductor 
Logotipo National Semiconductor Logotipo



Hay una vista previa y un enlace de descarga de CLC5523IN (archivo pdf) en la parte inferior de esta página.


Total 12 Páginas

No Preview Available ! CLC5523IN Hoja de datos, Descripción, Manual

March 2000
CLC5523
Low-Power, Variable Gain Amplifier
General Descriptions
The CLC5523 is a low power, wideband, DC-coupled, voltage-
controlled gain amplifier. It provides a voltage-controlled gain
block coupled with a current feedback output amplifier. High
impedance inputs and minimum dependence of bandwidth on
gain make the CLC5523 easy to use in a wide range of
applications. This amplifier is suitable as a continuous gain
control element in a variety of electronic systems which benefit
from a wide bandwidth of 250MHz and high slew rate of
1800V/ms, with only 135mW of power dissipation.
Input impedances in the megaohm range on both the signal
and gain control inputs simplify driving the CLC5523 in any
application. The CLC5523 can be configured to use pin 3 as a
low impedance input making it an ideal interface for current
inputs. By using the CLC5523’s inverting configuration in which
RG is driven directly, inputs which exceed the device’s input
voltage range may be used.
The gain control input (VG), with a 0 to 2V input range, and a
linear-in-dB gain control, simplifies the implementation of AGC
circuits. The gain control circuit can adjust the gain as fast as
4dB/ns. Maximum gains from 2 to 100 are accurately and simply
set by two external resistors while attenuation of up to 80dB from
this gain can be achieved.
The extremely high slew rate of 1800V/ms and wide bandwidth
provides high speed rise and fall times of 2.0ns, with settling time
for a 2 volt step of only 22ns to 0.2%. In time domain applications
where linear phase is important with gain adjust, the internal cur-
rent mode circuitry maintains low deviation of delay over a wide
gain adjust range.
Features
s Low power: 135mW
s 250MHz, -3dB bandwidth
s Slew rate 1800V/ms
s Gain flatness 0.2dB @ 75MHz
s Rise & fall times 2.0ns
s Low input voltage noise 4nV/ÖHz
Applications
s Automatic gain control
s Voltage controlled filters
s Automatic signal leveling for A/D
s Amplitude modulation
s Variable gain transimpedance
Frequency Response with Changes in Vg
30
20
10
0
-10
-20
-30
-40
-50
1M
10M 100M
Frequency (Hz)
Typical Application
Variable Gain Amplifier
Circuit
Vin
Rg
VG
+5V
2
1
+
8
CLC5523 6
3-
4
7
5 Rf
25W -5V
Vo
RL
Pinout
DIP & SOIC
VG
VIN
Rg
GND
X1
-
+
+VCC
I-
VO
-VCC
© 2000 National Semiconductor Corporation
Printed in the U.S.A.
http://www.national.com

1 page




CLC5523IN pdf
CLC5523 Operation
The key features of the CLC5523 are:
s Low Power
s Broad voltage controlled gain and attenuation
range
s Bandwidth independent, resistor programmable
gain range
s Broad signal and gain control bandwidths
s Frequency response may be adjusted with Rf
s High Impedance signal and gain control Inputs
The CLC5523 combines a closed loop input buffer, a volt-
age controlled variable gain cell and an output amplifier.
The input buffer is a transconductance stage whose gain
is set by the gain setting resistor, Rg. The output amplifi-
er is a current feedback op amp and is configured as a
transimpedance stage whose gain is set by, and equal to,
the feedback resistor, Rf. The maximum gain, Avmax, of
the CLC5523 is defined by the ratio; Rf / Rg. As the
gain control input (VG) is adjusted over its 0 to 2V range,
the gain is adjusted over a range of 80dB relative to the
maximum set gain.
Setting the CLC5523 Maximum Gain
A vmax
=
Rf
Rg
Although the CLC5523 is specified at Avmax = 10, the
recommended Avmax varies between 2 and 100. Higher
gains are possible but usually impractical due to
output offsets, noise and distortion. When varying Avmax
several tradeoffs are made:
Rg: determines the input voltage range
Rf: determines overall bandwidth
The amount of current which the input buffer can source
into Rg is limited and is specified in the IRgmax spec. This
sets the maximum input voltage:
Vin (max) = IRgmax × Rg
The effects of maximum input range on harmonic distortion
are illustrated in the Input Harmonic Distortion plot.
Variations in Rg will also have an effect on the small
signal bandwidth due to its loading of the input buffer and
can be seen in Frequency Response vs. Rg. Changes in
Rf will have a more dramatic effect on the small signal
bandwidth. The output amplifier of the CLC5523 is a
current feedback amplifier(CFA) and its bandwidth is
determined by Rf. As with any CFA, doubling the feed-
back resistor will roughly cut the bandwidth of the device
in half (refer to the plot Frequency Response vs. Rf). For
more information covering CFA’s, there is
a basic tutorial, OA-20, Current Feedback Myths
Debunked or a more rigorous analysis, OA-13, Current
Feedback Amplifier Loop Gain Analysis and Performance
Enhancements.
Using the CLC5523 in AGC Applications
In AGC applications, the control loop forces the CLC5523
to have a fixed output amplitude. The input amplitude will
vary over a wide range and this can be the issue that
limits dynamic range. At high input amplitudes, the
distortion due to the input buffer driving Rg may exceed
that which is produced by the output amplifier driving the
load. In the plot, Harmonic Distortion vs. Gain, second
and third harmonic distortion are plotted over a gain
range of nearly 40dB for a fixed output amplitude
of 100mVpp in the specified configuration, Rf = 1k,
Rg = 100W. When the gain is adjusted to 0.1 (i.e. 40dB
down from Avmax), the input amplitude would be 1Vpp and
we can see the distortion is at its worst at this gain. If the
output amplitude of the AGC were to be raised above
100mV, the input amplitudes for gains 40dB down from
Avmax would be even higher and the distortion would
degrade further. It is for this reason that we recommend
lower output amplitudes if wide gain ranges are desired.
Using a post-amp like the CLC404 or CLC409 would be
the best way to preserve dynamic range and yield output
amplitudes much higher than 100mVpp.
Another way of addressing distortion performance and
its limitations on dynamic range, would be to raise the
value of Rg. Just like any other high-speed amplifier, by
increasing the load resistance, and therefore decreasing
the demanded load current, the distortion performance
will be improved in most cases. With an increased Rg, Rf
will also have to be increased to keep the same Avmax
and this will decrease the overall bandwidth.
Gain Partitioning
If high levels of gain are needed, gain partitioning should
be considered.
Vin
R1
+
CLC425
-
R2
VG
252 1
Rc CLC5523 6
3
4 7 Rf
Rg 25W
Vo
Figure 1: Gain Partitioning
The maximum gain range for this circuit is given by the
following equation:
maximum
gain
=
æ
èç1+
R2
R1
ö
ø÷
×
æ
èç
Rf
Rg
ö
ø÷
5 http://www.national.com

5 Page





CLC5523IN arduino
+5V Rc
2k Rb
Level Adj.
100W
100W
Ci
100pF
150W
-5V
Signal
21
R1
100W
Input
U1 6
CLC5523
37
50W
2.2mF
Rg1
100W
4 Rf1
1k
Output
25W 2 1
U2 6
Rg2
CLC5523
37
100W
4
Rf2
1k
Figure 12: Automatic Gain Control Circuit #2
11 http://www.national.com

11 Page







PáginasTotal 12 Páginas
PDF Descargar[ Datasheet CLC5523IN.PDF ]




Hoja de datos destacado

Número de piezaDescripciónFabricantes
CLC5523ILow-Power/ Variable Gain AmplifierNational Semiconductor
National Semiconductor
CLC5523IMLow-Power/ Variable Gain AmplifierNational Semiconductor
National Semiconductor
CLC5523IMXLow-Power/ Variable Gain AmplifierNational Semiconductor
National Semiconductor
CLC5523INLow-Power/ Variable Gain AmplifierNational Semiconductor
National Semiconductor

Número de piezaDescripciónFabricantes
SLA6805M

High Voltage 3 phase Motor Driver IC.

Sanken
Sanken
SDC1742

12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters.

Analog Devices
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,
permitiéndote verlos en linea o descargarlos en PDF.


DataSheet.es    |   2020   |  Privacy Policy  |  Contacto  |  Buscar