Comlinear CLC427
Dual Voltage Feedback Amplifier for Single Supply Operation
August 1996
N
Comlinear CLC427
Dual Voltage Feedback Amplifier
for Single Supply Operation
General Description
The Comlinear CLC427 is a dual wideband voltage-feedback
operational amplifier that is uniquely designed to provide high
performance from a single power supply. This CLC427 provides
near rail-to-rail operation and the common-mode input range
includes the negative rail. Each of the CLC427’s amplifiers offers
plenty of headroom for single-supply applications as evidenced
by its 4.3V
pp
output voltage from a single 5V supply.
Fabricated with a high-speed complementary bipolar process,
the CLC427 delivers a wide 94MHz unity-gain bandwidth, 7.5ns
rise/fall time and 150V/µs slew rate. For single supply applications
such as video distribution or desktop multimedia, the CLC427
offers low 0.35%, 0.55° differential gain and phase errors.
Each of the CLC427’s amplifiers provides high signal fidelity
with -74/-94dBc 2nd/3rd harmonics (1V
pp
, 1MHz, R
L
=150Ω).
Combining this high fidelity performance with CLC427’s quick
46ns settling time to 0.1% makes it an excellent choice for ADC
buffering.
With its traditional voltage-feedback architecture and high-speed
performance, the CLC427 is the perfect choice for composite
signal conditioning circuit functions such as active filters,
integrators, differentiators, simple gain blocks and buffering.
Features
s
s
s
s
s
s
s
Single +5V supply
Input includes V
EE
94MHz unity-gain bandwidth
-74/-94dBc HD2/HD3
60mA output current
7.5ns rise/fall time (1V
pp
)
46ns settling time to 0.1%
Video ADC driver
Desktop multimedia
Single supply cable driver
Instrumentation
Video cards
Wireless IF amplifiers
Telecommunications
Frequency Response vs. V
out
A
v
= +2V/V
Applications
s
s
s
s
s
s
s
Magnitude (1dB/div)
1V
pp
2V
pp
4V
pp
1
10
100
Frequency (MHz)
Single Supply Response
Typical Application
Single +5V Supply operation
+5V
0.1µF
V
in
1/2
CLC427
V
CC
5
4
Output Voltage (V)
V
EE
3
2
1
0
6.8µF
+
V
o
+
-
Time (100ns/div)
150Ω
250Ω
50Ω
V
o1
V
CC
V
o2
V
inv2
V
non-inv2
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Pinout
DIP & SOIC
NOTE: V
in
= 0.15V to 2.3V
V
inv1
V
non-inv1
V
EE
250Ω
© 1996 National Semiconductor Corporation
Printed in the U.S.A.
Electrical Characteristics
PARAMETERS
(V
s
= +5V
1
, V
cm
= +2.5V, A
v
= +2, R
f
= 250
W,
R
L
= 150
W
to GND; unless specified)
TYP
25°
48
26
94
0.1
0
0.3
0.35
0.55
7.5
46
5
150
74
62
94
75
10
4
65
2
4
17
80
0.2
10
82
82
7
1
700
0.07
3.7
0
4.5
0.35
4.8
0.45
60
36
MIN/MAX RATINGS
25°
0° to +70° -40° to +85°
32
16
0.5
0.5
0.6
0.7
2
13
70
13
90
–
55
–
65
12.5
5
59
7
–
30
–
5
–
65
55
8.5
2
500
0.15
3.45
0
4.35
0.5
4.6
0.65
50
20
7
4
28
14
0.7
0.7
0.8
–
–
14
–
–
83
–
52
–
63
13.6
5.5
59
8
22
36
145
6
22
64
53
8.5
2
450
0.24
3.25
0
4.3
0.5
4.55
0.7
40
16
7
4
27
11
0.8
0.8
0.9
–
–
16
–
–
65
–
52
–
62
14
5.7
59
10
35
45
175
7.5
27
60
50
8.5
2
360
0.7
3.15
0
4.2
0.55
4.45
0.75
34
10
7
4
UNITS
NOTES
CONDITIONS
CLC427AJ
FREQUENCY DOMAIN RESPONSE
-3dB bandwidth
V
o
< 1.0V
pp
-3dB bandwidth
V
o
< 3.0V
pp
-3dB bandwidth A
V
= +1V/V
V
o
< 1.0V
pp
rolloff
<10MHz
peaking
DC to 200MHz
linear phase deviation
<15MHz
differential gain
NTSC, R
L
=150Ω
differential phase
NTSC, R
L
=150Ω
TIME DOMAIN RESPONSE
rise and fall time
settling time to 0.1%
overshoot
slew rate
A
V
= +2
1V step
1V step
1V step
2V step
MHz
MHz
MHz
dB
dB
deg
%
deg
ns
ns
%
V/µs
-dBc
-dBc
-dBc
-dBc
nV/√Hz
pA/√Hz
-dB
mV
µV/˚C
µA
nA/˚C
µA
nA/˚C
dB
dB
mA
pF
kΩ
Ω
V
V
V
V
V
V
mA
mA
V
V
B
B
B
2
2
DISTORTION AND NOISE RESPONSE
1V
pp
, 1MHz
2
nd
harmonic distortion
1V
pp
, 5MHz
3
rd
harmonic distortion
1V
pp
, 1MHz
1V
pp
, 5MHz
equivalent input noise
voltage
>1MHz
current
>1MHz
crosstalk, input referred
10MHz
STATIC DC PERFORMANCE
input offset voltage
average drift
input bias current
average drift
input offset current
average drift
power supply rejection ratio
common-mode rejection ratio
supply current (per amplifier)
B
B
A
A
DC
DC
no load
B
A
MISCELLANEOUS PERFORMANCE
input capacitance
input resistance
output impedance
@DC
input voltage range, high
input voltage range, low
output voltage range, high
R
L
= 150Ω
output voltage range, low
R
L
= 150Ω
output voltage range, high
no load
output voltage range, low
no load
output current
source
output current
sink
supply voltage, maximum
supply voltage, minimum
1
1
transistor count = 124
Min/max ratings are based on product characterization and simulation. Individual parameters are tested as noted. Outgoing quality levels are
determined from tested parameters.
Absolute Maximum Ratings
supply voltage (V
s
)
I
out
is short circuit protected to ground
common-mode input voltage
maximum junction temperature
storage temperature range
lead temperature (soldering 10 sec)
differential input voltage
ESD tolerance (Note 3)
+7V
V
EE
to V
CC
+175˚C
-65˚C to +150˚C
+260˚C
±2V
2000V
Notes
A) J-level: spec is 100% tested at 25°C, sample tested at 85°C.
B) J-level: spec is sample tested at 25°C.
1) V
s
= V
CC
– V
EE
.
2) Tested with R
L
tied to +2.5V.
3) Human body model, 1.5kΩ in series with 100pF.
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2
Typical Performance Characteristics
(V
s
= +5V
1
, V
cm
= +2.5V, A
v
= +2, R
f
= 250
Non-Inverting Frequency Response
V
o
= 0.25V
pp
A
v
= 1
R
f
= 0
W,
R
L
= 150
W
to GND; unless specified)
225
Inverting Frequency Response
V
o
= 0.25V
pp
Frequency Response vs. R
L
V
o
= 0.25V
pp
A
v
= -1
R
L
= 1kΩ
R
L
= 150Ω
R
L
= 75Ω
R
L
= 1kΩ
180
135
90
45
0
-45
-90
Magnitude (1dB/div)
Magnitude (1dB/div)
Magnitude (1dB/div)
A
v
= 4
A
v
= 2
A
v
= -5
A
v
= -2
Phase (deg)
Phase (deg)
Phase (deg)
A
v
= 10
A
v
= 10
A
v
= 1
A
v
= -10
A
v
= -1
A
v
= -10
A
v
= -5
A
v
= -2
0
-45
A
v
= 2
A
v
= 4
180
135
90
45
0
-45
-90
-135
-180
-225
R
L
= 75Ω
R
L
= 150Ω
-135
-180
-225
1
10
100
1
10
100
0
10
100
Frequency (MHz)
Frequency Response vs. V
out
Frequency (MHz)
Frequency Response vs. C
L
C
L
= 100pF
R
s
= 54.9Ω
C
L
= 1000pF
R
s
= 22Ω
C
L
= 10pF
R
s
= 249Ω
Frequency (MHz)
Open Loop Gain & Phase
100
0
-20
Gain
V
o
= 0.25V
pp
Open Loop Gain (dB)
Magnitude (1dB/div)
Magnitude (1dB/div)
80
60
40
20
0
-20
0.001
-40
-60
-80
Phase (deg)
Phase
V
o
= 4V
pp
V
o
= 2V
pp
V
o
= 1V
pp
R
s
C
L
250Ω
250Ω
1k
-100
-120
0.01
0.1
1
10
100
1
10
100
1
10
100
Frequency (MHz)
Harmonic Distortion vs. Frequency
-50
V
o
= 1V
pp
2nd
R
L
= 150Ω
Frequency (MHz)
2nd Harmonic Distortion vs. V
out
-30
R
L
= 150Ω
Frequency (MHz)
3rd Harmonic Distortion vs. V
out
-30
R
L
= 150Ω
-60
-40
10MHz
-40
Distortion (dBc)
Distortion (dBc)
Distortion (dBc)
-70
-80
-90
2nd
R
L
= 1kΩ
-50
-60
-70
-80
-90
5MHz
2MHz
-50
-60
-70
-80
-90
2MHz
5MHz
10MHz
3rd
R
L
= 1kΩ
3rd
R
L
= 150Ω
1MHz
0.1MHz
1MHz
0.1MHz
-100
0.1
1
10
-100
0
1
2
3
4
0
1
2
3
4
Frequency (MHz)
Small Signal Pulse Response
Output Voltage (0.05V/div)
Output Voltage (0.5V/div)
Output Amplitude (V
pp
)
Large Signal Pulse Response
100
Output Amplitude (V
pp
)
Equivalent Input Noise
100
Voltage Noise (nV/Hz)
Current Noise (pA/Hz)
10
Voltage = 9.5nV/√Hz
10
Current = 3.2pA/√Hz
Time (20ns/div)
I
B
, V
IO
, vs. Temperature
1.7
1.5
1.3
V
IO
Time (20ns/div)
Differential Gain and Phase (3.58MHz)
-10
-12
-14
2.5
R
L
tied to +2.5V
1
0.001
1
0.01
0.1
1
10
Frequency (MHz)
PSRR, CMRR & Linear R
out
vs. Frequency
2.5
2
100
80
60
40
20
R
out
PSRR
25
Output Resistance (Ω)
PSRR, CMRR (dB)
2
CMRR
20
15
10
5
0
Phase (deg)
Gain (%)
V
IO
(mV)
1.5
1
Phase Neg Sync
1.5
1
Gain Neg Sync
I
B
(µA)
1.1
0.9
0.7
0.5
-40
-20
0
20
I
B
-16
-18
-20
-22
40
60
80
0.5
0
1
2
3
4
0.5
0
0
0.001
0.01
0.1
1
10
Temperature (°C)
Number of 150Ω Loads
Frequency (MHz)
3
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CLC427 OPERATIONS
Description
The CLC427 contains two single supply voltage-feed-
back amplifiers. The CLC427 is a dual version of the
CLC423 with the following features:
• Operates from a single +5V supply
• Maintains near rail-to-rail performance
• Includes the negative rail (0V) in the Common
Mode Input Range (CMIR)
• Offers low -74/-94dBc 2nd and 3rd harmonic
distortion
• Provides BW > 20MHz and 1MHz distortion
< -50dBc at V
o
= 4V
pp
Single Supply Operation (V
CC
= +5V, V
EE
= GND)
The CLC427 is designed to operate from 0 and 5V
supplies. The specifications given in the
Electrical
Characteristics
table are measured with a common
mode voltage (V
cm
) of 2.5V. V
cm
is the voltage around
which the inputs are applied and the output voltages are
specified.
Operating from a single +5V supply, the CMIR of the
CLC427 is typically 0V to +3.7V. The typical output range
with R
L
= 150Ω is +0.35V to +4.5V.
For simple single supply operation, it is recommended
that input signal levels remain above ground. For input
signals that drop below ground, AC coupling and level
shifting the signal are possible remedies. For input
signals that remain above ground, no adjustments need
to be made. The non-inverting and inverting
configurations for both input conditions are illustrated in
the following 2 sections.
Standard Single Supply Operation
Figures 1 and 2 show the recommended non-inverting
and inverting configurations for purely positive input
signals.
+5V
6.8µF
+
+5V
6.8µF
+
3(5)
R
b
V
in
R
t
R
g
2(6)
1/2
CLC427
+
8
0.1µF
1(7)
V
o
-
4
R
f
R
V
o
=−
f
V
in
R
g
Select R
t
to yield
desired R
in
=
R
t
|| R
g
Figure 2: Inverting Configuration
Single Supply Operation for Inputs that go below 0V
Figures 3 and 4 show possible non-inverting and invert-
ing configurations for input signals that go below ground.
The input is AC coupled to prevent the need for level
shifting the input signal at the source. The resistive volt-
age divider biases the non-inverting input to V
CC
÷ 2 =
2.5V.
+5V
6.8µF
+
V
in
C
c
2.5V
R
3(5)
R
2(6)
1/2
CLC427
+
8
0.1µF
1(7)
V
o
-
4
R
f
R
V
o
=
V
in
1
+
f
+
2.5
R
g
low frequency cutoff
=
R
g
C
1
R
, where: R
in
=
2
π
R
in
C
c
2
R
g
C
>>
RC
c
R >> R
source
Figure 3: AC Coupled Non-inverting Configuration
+5V
6.8µF
+
2.5V
R
3(5)
2(6)
V
in
R
t
3(5)
2(6)
1/2
CLC427
+
8
0.1µF
1(7)
V
o
V
in
C
c
R
g
R
1/2
CLC427
+
8
0.1µF
1(7)
V
o
-
-
4
R
f
4
R
f
R
V
o
=
V
in
−
f
+
2.5
R
g
low frequency cutoff
=
R
g
R
V
o
=
1
+
f
V
in
R
g
1
2
π
R
g
C
c
Figure 1: Non-inverting Configuration
Figure 4: AC Coupled Inverting Configuration
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4
Crosstalk (dB)
Load Termination
Since the CLC427 design has been optimized for Single
Supply Operation, it is more capable of sourcing rather
than sinking current. For optimum performance, the load
should be tied to V
EE
. When the load is tied to V
EE
, the
output always sources current.
Output Overdrive Recovery
When the output range of an amplifier is exceeded, time
is required for the amplifier to recover from this over
driven condition. Figure 5 illustrates the overload
recovery of the CLC427 when the output is overdriven.
An input was applied in an attempt to drive the
output to twice the supply rails, V
CC
- V
EE
= 10V, but
the output limits. An inverting gain topology was used,
see Figure 2. As indicated, the CLC427 recovers within
25ns on the rising edge and within 10ns on the falling
edge.
Input
-40
-50
-60
-70
-80
-90
-100
1
10
100
Frequency (MHz)
Figure 7: Input Referred Crosstalk vs. Frequency
Output Channel B (20mV/div)
Output Channel A (1V/div)
Channel A
Output Voltage (2V/div)
Input Voltage (4V/div)
Channel B
Output
Time (50ns/div)
Figure 8: Pulsed crosstalk
Time (50ns/div)
Figure 5: Overdrive Recovery
Channel Matching
Channel matching and crosstalk rejection are largely
dependent on board layout. The layout of Comlinear’s
dual amplifier evaluation boards are designed to produce
optimum channel matching and isolation. Channel
matching for the CLC427 is shown in Figure 6.
Driving Cables and Capacitive Loads
When driving cables, double termination is used to
prevent reflections. For capacitive load applications, a
small series resistor at the output of the CLC427 will
improve stability. The
Frequency Response vs.
Capacitive Load
plot, in the typical performance
section, gives the recommended series resistance value
for optimum flatness at various capacitive loads.
Power Dissipation
The power dissipation of an amplifier can be described in
two conditions:
• Quiescent Power Dissipation -
P
Q
(No Load Condition)
• Total Power Dissipation -
P
T
(with Load Condition)
The following steps can be taken to determine the power
consumption for each CLC427 amplifier:
V
out
= 0.25V
pp
Magnitude (0.5dB/div)
Channel A
Channel B
1
10
Frequency (MHz)
Figure 6: Channel Matching
The CLC427’s channel-to-channel isolation is better than
-70dB for video frequencies of 4MHz. Input referred
crosstalk vs frequency is illustrated in Figure 7. Pulsed
crosstalk is shown in Figure 8.
1. Determine the quiescent power
P
Q
= I
CC
(V
CC
– V
EE
)
2. Determine the RMS power at the output stage
P
O
= (V
CC
– V
load
) (I
load
)
3. Determine the total RMS power
P
T
= P
Q
+ P
O
Add the total RMS powers for both channels to determine
the power dissipated by the dual.
5
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