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CLC449
1.1GHz Ultra Wideband Monolithic Op Amp
The CLC449 is an ultra high speed monolithic op amp, with a typical -3dB bandwidth of 1.1GHz at a gain
of +2. This wideband op amp supports rise and fall times less than 1ns, settling time of 6ns (to 0.2%) and
slew rate of 2500V/µs. The CLC449 achieves 2nd harmonic distortion of -68dBc at 5MHz at a low supply
current of only 12mA.
The DC to 1.2 GHz bandwidth of the CLC449 is suitable for many IF and RF applications as a versatile op
amp building block for replacement of AC coupled discrete designs. Operational amplifier functions such
as active filters, gain blocks, differentiation, addition, subtraction and other signal conditioning functions
take full advantage of the CLC449’s unity-gain stable closed-loop performance.
Rochester Electronics
Manufactured Components
Rochester branded components are
manufactured using either die/wafers
purchased from the original suppliers
or Rochester wafers recreated from the
original IP. All recreations are done with
the approval of the OCM.
Parts are tested using original factory
test programs or Rochester developed
test solutions to guarantee product
meets or exceeds the OCM data sheet.
Quality Overview
•
•
•
•
ISO-9001
AS9120 certification
Qualified Manufacturers List (QML) MIL-PRF-38535
• Class Q Military
• Class V Space Level
Qualified Suppliers List of Distributors (QSLD)
• Rochester is a critical supplier to DLA and
meets all industry and DLA standards.
Rochester Electronics, LLC is committed to supplying
products that satisfy customer expectations for
quality and are equal to those originally supplied by
industry manufacturers.
The original manufacturer’s datasheet accompanying this document reflects the performance
and specifications of the Rochester manufactured version of this device. Rochester Electronics
guarantees the performance of its semiconductor products to the original OEM specifications.
‘Typical’ values are for reference purposes only. Certain minimum or maximum ratings may be
based on product characterization, design, simulation, or sample testing.
© 2013 Rochester Electronics, LLC. All Rights Reserved 08282013
To learn more, please visit www.rocelec.com
CLC449
1.1GHz Ultra Wideband Monolithic Op Amp
General Description
Features
The CLC449 is an ultra high speed monolithic op amp, with
a typical −3dB bandwidth of 1.1GHz at a gain of +2. This
wideband op amp supports rise and fall times less than 1ns,
settling time of 6ns (to 0.2%) and slew rate of 2500V/µs. The
CLC449 achieves 2nd harmonic distortion of −68dBc at
5MHz at a low supply current of only 12mA. These
performance advantages have been achieved through
improvements in National’s proven current feedback
topology combined with a high speed complementary bipolar
process.
The DC to 1.2GHz bandwidth of the CLC449 is suitable for
many IF and RF applications as a versatile op amp building
block for replacement of AC coupled discrete designs.
Operational amplifier functions such as active filters, gain
blocks, differentiation, addition, subtraction and other signal
conditioning functions take full advantage of the CLC449’s
unity-gain stable closed-loop performance.
The CLC449 performance provides greater headroom for
lower frequency applications such as component video, high
resolution workstation graphics, and LCD displays. The
amplifier’s 0.1dB gain flatness to beyond 200MHz, plus
0.8ns (2V step) rise and fall times are ideal for improved time
domain performance. In addition, the 0.03%/0.02˚ differential
gain/phase performance allows system flexibility for handling
standard NTSC and PAL signals.
In applications using high speed flash A/D and D/A
converters, the CLC449 provides the necessary wide
bandwidth (1.1GHz), settling (6ns to 0.02%) and low
distortion into 50Ω loads to improve SFDR.
n
n
n
n
n
n
n
n
1.1GHz small-signal bandwidth (Av =+2)
2500V/µs slew rate
0.03%, 0.02˚ DG, DΦ
6ns settling time to 0.2%
3rd order intercept, 30dBm @ 70MHz
Dual ± 5V or single 10V supply
High output current: 80mA
2.5dB noise figure
Applications
n
n
n
n
n
n
n
High performance RGB video
RF/IF amplifier
Instrumentation
Medical electronics
Active filters
High speed A/D driver
High speed D/A buffer
Frequency Response (AV = +2V/V)
DS012715-1
Connection Diagram
DS012715-3
Pinout
DIP & SOIC
© 2001 National Semiconductor Corporation
DS012715
www.national.com
CLC449 1.1GHz Ultra Wideband Monolithic Op Amp
February 2001
CLC449
Typical Application
DS012715-2
120MSPS High Speed Flash ADC Driver
Ordering Information
Package
Temperature Range
Industrial
Part Number
Package Marking
NSC Drawing
8-pin plastic DIP
−40˚C to +85˚C
CLC449AJP
CLC449AJP
N08E
8-pin plastic SOIC
−40˚C to +85˚C
CLC449AJE
CLC449AJE
M08A
www.national.com
2
Storage Temperature Range
Lead Solder Duration (+300˚C)
ESD (human body model)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage (VCC)
IOUT is short circuit protected to
ground
Common Mode Input Voltage
Maximum Junction Temperature
Operating Temperature Range
−65˚C to +150˚C
10 sec
500V
Operating Ratings
± 6V
Thermal Resistance
Package
MDIP
SOIC
± VCC
+150˚C
−40˚C to +85˚C
(θJC)
90˚C/W
110˚C/W
(θJA)
105˚C/W
130˚C/W
Electrical Characteristics
AV = +2, VCC = ± 5V, RL = 100Ω, Rf = 250Ω; unless specified
Symbol
Parameter
Ambient Temperature
Conditions
Typ
CLC449AJ
+25˚C
< 0.2VPP
< 2.0VPP
< 2.0VPP
1100
Min/Max (Note 2)
Units
+25˚C
0 to
70˚C
−40 to
+85˚C
380
380
360
Frequency Domain Response
-3dB Bandwidth
Small Signal
Large Signal
± 0.1 dB Bandwidth
500
MHz
200
MHz
MHz
Gain Glatness
Peaking
DC to 200MHz
0
Rolloff
DC to 200MHz
0.1
dB
Linear Phase Deviation
< 200MHz
0.8
Differential Gain
RL = 150Ω,
4.43MHz
0.03
0.05
0.05
0.05
%
Differential Phase
RL = 150Ω,
4.43MHz
0.02
0.02
0.05
0.05
deg
Rise and Fall Time
2V Step
0.8
1.1
1.1
1.1
Settling Time to ± 0.2%
2V Step
6
0.5
0.5
0.5
dB
deg
Time Domain Response
ns
ns
Settling Time to ± 0.1%
2V Step
11
Overshoot
2V Step
10
18
18
18
%
Slew Rate
4V Step
2500
2000
2000
2000
V/µs
ns
Distortion And Noise Response
2nd Harmonic Distortion
3rd Harmonic Distortion
3rd Order Intercept
2VPP, 5MHz
−63
−59
−59
−59
dBc
2VPP, 20MHz
−52
−48
−48
−48
dBc
2VPP, 50MHz
−44
−40
−40
−40
dBc
2VPP, 5MHz
−84
−77
−75
−75
dBc
2VPP, 20MHz
−73
−66
−64
−64
dBc
2VPP, 50MHz
−62
−55
−53
−53
dBc
70MHz
1dB Gain Compression @ 50MHz
30
dBm
16
dBm
Equivalent Input Noise
Non-Inverting Voltage
1MHz
2.2
2.9
nV/
Inverting Current
1MHz
15
20.0
pA/
Non-Inverting Current
1MHz
3
5.0
pA/
3
7
Static, DC Performance
Input Offset Voltage (Note 3)
3
9
9
mV
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CLC449
Absolute Maximum Ratings (Note 1)
CLC449
Electrical Characteristics
(Continued)
AV = +2, VCC = ± 5V, RL = 100Ω, Rf = 250Ω; unless specified
Symbol
Parameter
Conditions
Typ
Min/Max (Note 2)
Units
Static, DC Performance
Average Drift
Input Bias Current (Note 3)
25
Non-Inverting
6
Average Drift
Input Bias Current (Note 3)
µV/C˚
30
45
60
50
Inverting
2
Average Drift
µA
nA/˚C
20
25
40
25
µA
nA/C˚
Power Supply Rejection Ratio
DC
48
43
41
41
Common Mode Rejection Ratio
DC
47
44
45
46
dB
dB
Supply Current (Note 3)
RL = ∞
12
13.5
14
14
mA
Input Resistance
Non-Inverting
400
200
200
150
KΩ
Input Capacitance
Non-Inverting
1.3
Output Resistance
Closed Loop
0.1
0.15
0.15
0.25
Output Voltage Range
RL = ∞
3.3
3.1
3.1
3.1
V
RL = 100Ω
2.9
2.8
2.8
2.8
V
Common-Mode
2.4
2.2
2.1
1.9
V
80
60
50
40
mA
Miscellaneous Performance
Input Voltage Range
Output Current
pF
Ω
Note 1: “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. They are not meant to imply that the devices
should be operated at these limits. The table of “Electrical Characteristics” specifies conditions of device operation.
Note 2: Min/max ratings are based on product characterization and simulation. Individual parameters are tested as noted. Outgoing quality levels are determined
from tested parameters.
Note 3: AJ-level: spec. is 100% tested at +25˚C.
Typical Performance Characteristics
Non-Inverting Frequency Response
Inverting Frequency Response
DS012715-4
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DS012715-5
4
(Continued)
Frequency Response vs. Load
Open Loop Transimpedance, Z(s)
DS012715-6
Harmonic Distortion vs. Frequency
CLC449
Typical Performance Characteristics
DS012715-7
2-Tone, 3rd Order Intermodulation Intercept
DS012715-8
2nd Harmonic Distortion vs. Pout
DS012715-9
3rd Harmonic Distortion vs. Pout
DS012715-10
DS012715-11
5
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Gain Flatness and Linear Phase
Equivalent Input Noise
Phase (1deg/div)
Noise Voltage (nV/√Hz), Current (pA/√Hz)
(Continued)
Magnitude (0.1dB/div)
CLC449
Typical Performance Characteristics
DS012715-12
0.1k
1k
10k
100k
1M
Frequency (Hz)
10M
100M
DS012715-13
Single Supply −3dB Bandwidth
Differential Gain and Phase
DS012715-14
PSRR, CMRR, and Closed Loop ROUT
DS012715-15
Small Signal Pulse Response
DS012715-17
DS012715-16
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6
(Continued)
Large Signal Pulse Response
Gain Compression
CLC449
Typical Performance Characteristics
DS012715-18
DS012715-19
RS and Settling Time vs. CL
Input Bias Current, IBI, IBN (µA)
Input Offset Voltage, VIO (mV)
Typical IBI, IBN, VIO vs. Temperature
DS012715-20
DS012715-21
Input VSWR
Output VSWR
DS012715-22
DS012715-23
7
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(Continued)
Reverse Isolation (S12)
-10
-20
-30
-40
|S12| (dB)
CLC449
Typical Performance Characteristics
-50
-60
-70
-80
-90
-100
0
100M
200M
300M
Frequency (Hz)
400M
500M
DS012715-24
Rf ) 340 − AV x Ri where Ri = 45Ω. For AV > 5, the minimum
recommended Rf is 100Ω.
Select Rg to set the DC gain:
Application Division
CLC449 Operation
CLC449 Extended Application Information
The following design and application topics will supply you
with:
•
A comprehensive set of design parameters and design
parameter adjustment techniques.
•
A set of formulas that support design parameter change
prediction
•
A series of common applications that the CLC449
supports.
Accuracy of DC gain is usually limited by the tolerance of Rf
and Rg.
DC Gain (unity gain buffer)
Unity gain buffers are easily designed with a
current-feedback amplifier as long as the recommended
feedback resistor Rf = 402Ω is used and Rg = ∞, i.e., open.
Parasitic capacitance at the inverting node may require a
slight increase of Rf to maintain a flat frequency response.
DC Gain (inverting)
The inverting DC voltage gain for the configuration shown in
Figure 2 is
• A set of easy to use design guidelines for the CLC449.
Additional design applications are possible with the CLC449.
If you have application questions, call 1-800-272-9959 in the
U.S. to contact a technical staff member.
DC Gain (Non-inverting)
The non-inverting DC voltage gain for the configuration
shown in is:
DS012715-25
FIGURE 1. Non-Inverting Gain
The normalized gain plots in the Typical Performance
Characteristics section show different feedback resistors,
Rf, for different gains. These values of Rf are recommended
for obtaining the highest bandwidth with minimal peaking.
The resistor t in Figure 1 provides DC bias for the
non-inverting input.
For Av ≤5, calculate the recommended Rf as follows:
www.national.com
DS012715-28
FIGURE 2. Inverting Gain
8
CLC449
Application Division
(Continued)
Req1
The normalized gain plots in the Typical Performance
Characteristics section show different feedback resistors Rf
for different gains. These values of Rf are recommended for
obtaining the highest bandwidth with minimal peaking. The
resistor Rt in Figure 2 provides DC bias for the non-inverting
input.
For |Av|≤4, calculate the recommended Rf as follows:
Vin
Req2
Vref
Rref
+
Vo
CLC449
Rf
DS012715-31
FIGURE 3. Level Shifting Circuit
Rf ) 295 − |AV| x Ri where Ri = 45Ω. For |AV| > 4, the
minimum recommended Rf is 100Ω.
DC Design (Single Supply)
Figure 4 is a typical single-supply circuit. Resistors R1 and
R2 form a voltage divider that sets the non-inverting input DC
voltage. This circuit has a DC gain of 1. The coupling
capacitor C1 isolates the DC bias point from the previous
stage. Both capacitors make a high pass response; the high
frequency gain is determined by Rf and Rg.
Select Rg to set the DC gain:
At large gains, Rg becomes small and will load the previous
stage. This situation is resolved by driving Rg with a low
impedance buffer like the CLC111, or increasing Rf and Rg
see the Bandwidth (Small Signal) sub-section for the
tradeoffs).
Accurate DC gain is usually limited by the tolerance of the
external resistors Rf and Rg.
Bandwidth (Small Signal)
The CLC449 current-feedback amplifier bandwidth is a
function of the feedback resistor (Rf), not of the DC voltage
gain (Av). The bandwidth is approximately proportional to
1/Rf. As a rule, if Rf doubles, the bandwidth is cut in half.
Other AC specifications will also be degraded. Decreasing
Rf from the recommended value increases peaking and
for very small values of Rf oscillation will occur.
With an inverting amplifier design, peaking is sometimes
observed. This is often the result of layout parasitics caused
by inadequate ground planes or long traces. If this is
observed, placing a 50 to 200Ω resistor between the
non-inverting pin and ground will usually reduce the peaking.
Bandwidth (Minimum Slew Rate)
Slew rate influences the bandwidth for large signal
sinusoids. To determine an approximate value of slew rate,
necessary to support large sinusoids use the following
equation:
SR)5 x f x Vpeak
Vcc
Vcc
R1
Vin
+
C1
Vo
CLC449
R2
Rf
Rg
C2
DS012715-32
FIGURE 4. Single Supply Circuit
The complete gain equation for the circuit in Figure 4 is
 R 
1 + sτ 2 ⋅ 1 + f 
 Rg 
sτ1
Vo
=
⋅
Vin 1 + sτ1
1 + sτ 2
Vpeak is the peak output sinusoid voltage, f is the frequency
of the sinusoid.
The slew rate of the CLC449 in inverting gains is always
higher than in non-inverting gains.
DC Design (Level Shifting)
where s = jω, τ1 = (R1\R2) x C1, and τ2 = RgC2.
DC Design (DC Offsets)
The DC offset model shown in Figure 5 is used to calculate
the output offset voltage. The equation for output offset
voltage is:
Figure 3 shows a DC level shifting circuit for inverting gain
configurations. Vref produces a DC output level shift of

Rf 
Vo = − Vos + IBN ⋅ Req1 ⋅ 1 +
 + (IBI ⋅ R f )
 Req2 
(
)
The current offset terms, IBN and IBI, do not track each
other. The specifications are stated in terms of magnitude
only. Therefore, the terms VOS, IBN, and IBI may have either
positive or negative polarity. Matching the equivalent
resistance seen at both input pins does not reduce the
output offset voltage.
which is independent of the DC output produced by Vin.
9
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CLC449
Application Division
Thermal Design
(Continued)
To calculate the power dissipation for the CLC449, follow
these steps:
IBN
+
Req1
+
Vos CLC449
IBI
Rf
1. Calculate the no-load op amp power:
Pamp = Icc (Vcc−VEE)
2. Calculate the output stage’s RMS power:
Vo
Po = (Vcc − Vload) Iload, where Vload and Iload are the RMS
voltage and current across the external load.
3. Calculate the total op amp RMS power:
Pt = Pamp + Po
RL
Req2
To calculate the maximum allowable ambient temperature,
solve the following equation: Tamb = 150 − Pt x θJA where θJA
is the thermal resistance from junction to ambient in ˚C/W,
and Tamb is in ˚C. The Package Thermal Resistance
section contains the thermal resistance for various
packages.
Dynamic Range (input/output protection)
Input ESD diodes are present on all connected pins for
protection from static voltage damage. For a signal that may
exceed the supply voltages, we recommend using diode
clamps at the amplifier’s input to limit the signals to less than
the supply voltages.
Dynamic Range (input/output levels) The Electrical
Characteristics section specifies the Common-Mode Input
Range and Output Voltage Range; these voltage ranges
scale with the supplies. Output Current also specified in the
Electrical Characteristics section.
Unity gain applications are limited by the Common-Mode
Input Range. At greater non-inverting gains, the Output
Voltage Range becomes the limiting factor. Inverting gain
applications are limited by the Output Voltage Range.
For transimpedance or inverting gain applications, the
current (Iinv) injected at the inverting input of the op amp
needs to be:
DS012715-35
FIGURE 5. DC Offset Model
DC Design (Output Loading)
RL, Rf, and Rg load the op amp output. The equivalent
closed-loop load impedance seen by the output in Figure 5
is:
RL_eq = RL\ (Rf+Req2), non-inverting gain
RL_eq = RL\ Rf inverting gain
RL_eq needs to be kept large enough so that the minimum
available output current can produce the required output
voltage swing.
Capacitive Loads
Capacitive loads, such as found in A/D converters, require a
series resistor (Rs in the output to improve settling
performance. The Rs and Settling Time vs. CL plot in the
Typical Performance Characteristics section provides the
information for selecting this resistor.
Also, use a series resistor to reduce the effects of reactive
loads on amplifier loop dynamics. For instance, driving
coaxial cables without an output series resistor may cause
peaking or oscillation.
Transmission Line Matching
One method for matching the characteristic impedance of a
transmission line is to place the appropriate resistor at the
input or output of the amplifier. Figure 6 shows the typical
circuit configurations for matching transmission lines.
In non-inverting gain applications, Rg is connected directly to
ground. The resistors R1, R2, R6, and R7 are equal to the
characteristic impedance
DS012715-36
FIGURE 6. Transmission Line Matching
where:
In inverting gain applications, R3 is connected directly to
ground. The resistor R4, R6, and R7 are equal to Z0. The
parallel combination of R5 and Rg is also equal to Z0.
•
•
•
The input and output matching resistors attenuate the signal
by a factor of 2, therefore additional gain is needed. Use C6
to match the output transmission line over a greater
frequency range. It compensates for the increase of the op
amp’s output impedance with frequency.
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where Vmax is the Output Voltage Range .
The voltage ranges discussed above are achieved as long
as the equivalent output load is large enough so that the
output current can produce the required output voltage
swing. See the DC Design (output loading ) sub-section for
details.
Dynamic Range (Intermods)
In RF applications, the CLC449 specifies a third order
intercept of 30dBm at 70MHz and PO = 10dBm.at a gain of
10. A2-Tone, 3rd Order IMD Intercept plot is found in the
Typical Performance Characteristics section. The output
power level is taken at the load. Third-order harmonic
distortion is calculated with the formula:
HD3rd = 2 x (IP3O − PO)
10
IP3O =Third-order output intercept, dBm at the load.
PO = output power level, dBm at the load.
HD3rd = Third-order distortion from the fundamental,
−dBc.
(Continued)
• dBm is the power in mW, at the load, expressed in dB.
Realized third-order output distortion is highly dependent
upon the external circuit. Some of the common external
circuit choices that improve 3rd order distortion are:
• short and equal return paths from the load to the
supplies.
• de-coupling capacitors of the correct value.
• higher load resistance
• a lower ratio of the output swing to the power supply
voltage.
Dynamic Range (Noise)
In RF applications, noise is frequently specified as Noise
Figure (NF). Figure 7 plots NF for the CLC449 at a gain of
10, with a feedback resistor Rf of 100Ω, and with no input
matching resistor. The minimum Noise Figure (2.5dB) for
these conditions occurs when the source resistance equals
700Ω.
Noise Figure (dB)
There is no matching resistor from the input to ground.
•
•
4kT = 16 x 10−21J, T= 290˚K.
•
•
•
Use a ground plane
•
tantalum capacitors of about 6.8µF for large signal
current swings or improved power supply noise rejection;
we recommend a minimum of 2.2 µF for any circuit
•
Minimize trace and lead lengths for components between
the inverting and output pins
•
Remove ground plane underneath the amplifier package
and 0.1” (3mm) from all input/output pads
eni, ibn, ibi are the voltage and current noise density terms
(see in the Distortion and Noise Response sub-section
of the Electrical Characteristics section).
Rf is the feedback resistor and Rg is the gain setting
resistor.
Printed Circuit Board Layout
High Frequency op amp performance is strongly dependent
on proper layout, proper resistive termination and adequate
power supply decoupling. The most important layout points
to follow are:
20
15
Bypass power supply pins with monolithic:
ceramic capacitors of about 0.1µF placed less than 0.1”
(3mm) from the pin
•
If parts must be socketed, always use flush-mounted
socket pins instead of high profile sockets.
Evaluation boards are available for proto-typing and
measurements. Additional layout information is available in
the evaluation board literature.
Low Noise Composite Amp With Input Matching
The composite circuit shown in Figure 9 eliminates the need
for a matching resistor to ground at the input. By connecting
two amplifiers in series, the first non-inverting and second
inverting, an overall inverting gain is realized. The feedback
resistor (Rf) connected from the output of the second
amplifier to the non-inverting input of the first amplifier closes
the loop, and generates a set input resistance (Rin) that can
be matched to Rs. This resistor generates less noise than a
matching resistor to ground at the input.
10
5
0
10
1000
100
10000
Source Resistance (Ω)
DS012715-38
FIGURE 7. Noise Figure Plot
en
Rs
Vs
•
•
+
-
Rf
+
*
*
CLC449
ibn
Vo
Rf2
Rin
Vs +-
-
+
Rs
-
-
CLC449
Rf1
Rf
Rg1
*
ibi
Vo
+
20Ω
Rg
DS012715-41
FIGURE 9. Composite Amplifier
The input resistance and DC voltage gain of the amplifier
are:
DS012715-39
FIGURE 8. CLC449 Noise Model
Rin =
The CLC449 noise model in Figure 8 is used to develop the
equation below.
The equation for Noise Figure (NF) is:
(
 e + i R 2 + 4kTR + i ⋅ R ||R
2
( bn s )
s
g
bi
f
NF = 10LOG  ni

4kTRs

)
2
 R  R 
Rf
, where G = 1+ f 1  ⋅  f2 
1+ G
 R g1   R g2 
 Rin 
Vo
= − G⋅

Vs
 Rin + R s 
+ 4kT ⋅ R f ||R g 



Match the source resistance by setting: Rin = Rs
Where:
•
Rg2
CLC449
Noise voltage produced by Rf, referred to the source Vs is:
Rs is the source resistance at the non-inverting input.
11
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CLC449
Application Division
CLC449
Application Division
(Continued)


Rs
e 2R = 4kTRs ⋅ 

f
 Rin ⋅ (1 + G) 
The noise of a simple input matching resistor connected to
ground can be calculated by setting G to 0 in this equation.
Thus, this circuit reduces the thermal noise power produced
by the matching resistor by a factor of (1+G).
Rectifier Circuit
Wide bandwidth rectifier circuits have many applications.
Figure 10 shows a 200MHz wideband full-wave rectifier
circuit using a CLC449 and a CLC522 amplifier. Schottky or
PIN diodes are used for D1 and D2. They produce an active
half-wave rectifier whose signals are taken at the feedback
diode connection. The CLC522 takes the difference of the
two half-wave rectified signals, producing a full-wave
rectifier. The CLC522 is used at a gain of 5 to achieve high
differential bandwidth. For best high frequency performance,
maintain low parasitic capacitance from the diodes D1 and
D2 to ground, and from the input of the CLC522 to ground.
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DS012715-44
FIGURE 10. Full-Wave Rectifier
Flash A/D Application
The Typical Application circuit on the front page shows the
CLC449 driving a flash A/D. Flash A/D’s require fast settling,
low distortion, low noise and wide bandwidth to achieve high
Effective Number of Bits and Spurious Free Dynamic Range
(SFDR).
This circuit connects a CLC449 to a TDA8716, 8-bit,
120MHz Flash Converter. The input capacitance for this
converter is typically 13pF plus layout capacitace. From the
Rs and Settling Time vs. CL plot in the Typical
Performance Characteristics section, select a series
resistor (Rs) of 55Ω. Place Rs in series with the output of the
CLC449 to achieve settling to 0.1% in approximately 11ns.
Keep the amplifier noise seen at the A/D input at least 3dB
lower than the A/D’s noise, to avoid degrading A/D noise
performace.
12
CLC449
Physical Dimensions
inches (millimeters) unless otherwise noted
8-Pin SOIC
NS Package Number M08A
8-Pin MDIP
NS Package Number N08E
13
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CLC449 1.1GHz Ultra Wideband Monolithic Op Amp
Notes
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