NSC CLC427 Dual voltage feedback amplifier for single supply operation Datasheet

N
Comlinear CLC427
Dual Voltage Feedback Amplifier
for Single Supply Operation
General Description
Features
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 4.3Vpp 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.
■
■
■
■
■
■
Applications
■
■
■
■
■
■
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.
■
Video ADC driver
Desktop multimedia
Single supply cable driver
Instrumentation
Video cards
Wireless IF amplifiers
Telecommunications
Frequency Response vs. Vout
Av = +2V/V
Magnitude (1dB/div)
Each of the CLC427’s amplifiers provides high signal fidelity
with -74/-94dBc 2nd/3rd harmonics (1Vpp, 1MHz, RL=150Ω).
Combining this high fidelity performance with CLC427’s quick
46ns settling time to 0.1% makes it an excellent choice for ADC
buffering.
Single +5V supply
Input includes VEE
94MHz unity-gain bandwidth
-74/-94dBc HD2/HD3
60mA output current
7.5ns rise/fall time (1Vpp)
46ns settling time to 0.1%
1Vpp
2Vpp
4Vpp
1
10
Comlinear CLC427
Dual Voltage Feedback Amplifier for Single Supply Operation
August 1996
100
Frequency (MHz)
Single Supply Response
Typical Application
VCC
Single +5V Supply operation
0.1µF
6.8µF
+
+
1/2
CLC427
-
Vo
Output Voltage (V)
4
+5V
Vin
5
VEE
3
2
1
0
Time (100ns/div)
150Ω
50Ω
Pinout
250Ω
DIP & SOIC
250Ω
Printed in the U.S.A.
VCC
Vinv1
Vo2
Vnon-inv1
NOTE: Vin = 0.15V to 2.3V
© 1996 National Semiconductor Corporation
Vo1
VEE
Vinv2
Vnon-inv2
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Electrical Characteristics
PARAMETERS
(Vs = +5V1, Vcm = +2.5V, Av = +2, Rf = 250W, RL = 150W to GND; unless specified)
CONDITIONS
CLC427AJ
TYP
25°
25°
MIN/MAX RATINGS
0° to +70° -40° to +85°
UNITS
NOTES
B
FREQUENCY DOMAIN RESPONSE
-3dB bandwidth
Vo < 1.0Vpp
-3dB bandwidth
Vo < 3.0Vpp
-3dB bandwidth AV = +1V/V
Vo < 1.0Vpp
rolloff
<10MHz
peaking
DC to 200MHz
linear phase deviation
<15MHz
differential gain
NTSC, RL=150Ω
differential phase
NTSC, RL=150Ω
48
26
94
0.1
0
0.3
0.35
0.55
32
16
28
14
27
11
0.5
0.5
0.6
0.7
2
0.7
0.7
0.8
–
–
0.8
0.8
0.9
–
–
MHz
MHz
MHz
dB
dB
deg
%
deg
TIME DOMAIN RESPONSE
rise and fall time
settling time to 0.1%
overshoot
slew rate
AV = +2
7.5
46
5
150
13
70
13
90
14
–
–
83
16
–
–
65
ns
ns
%
V/µs
74
62
94
75
–
55
–
65
–
52
–
63
–
52
–
62
-dBc
-dBc
-dBc
-dBc
10
4
65
12.5
5
59
13.6
5.5
59
14
5.7
59
nV/√Hz
pA/√Hz
-dB
2
4
17
80
0.2
10
82
82
7
7
–
30
–
5
–
65
55
8.5
8
22
36
145
6
22
64
53
8.5
10
35
45
175
7.5
27
60
50
8.5
mV
µV/˚C
µA
nA/˚C
µA
nA/˚C
dB
dB
mA
1
700
0.07
3.7
0
4.5
0.35
4.8
0.45
60
36
2
500
0.15
3.45
0
4.35
0.5
4.6
0.65
50
20
7
4
2
450
0.24
3.25
0
4.3
0.5
4.55
0.7
40
16
7
4
2
360
0.7
3.15
0
4.2
0.55
4.45
0.75
34
10
7
4
pF
kΩ
Ω
V
V
V
V
V
V
mA
mA
V
V
1V step
1V step
1V step
2V step
DISTORTION AND NOISE RESPONSE
1Vpp, 1MHz
2nd harmonic distortion
1Vpp, 5MHz
3rd harmonic distortion
1Vpp, 1MHz
1Vpp, 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)
DC
DC
no load
MISCELLANEOUS PERFORMANCE
input capacitance
input resistance
output impedance
@DC
input voltage range, high
input voltage range, low
output voltage range, high
RL = 150Ω
output voltage range, low
RL = 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
B
B
2
2
B
B
A
A
B
A
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 (Vs)
Iout 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)
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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) Vs = VCC – VEE.
2) Tested with RL tied to +2.5V.
3) Human body model, 1.5kΩ in series with 100pF.
+7V
VEE to VCC
+175˚C
-65˚C to +150˚C
+260˚C
±2V
2000V
2
Typical Performance Characteristics (Vs = +5V1, Vcm = +2.5V, Av = +2, Rf = 250
W,
Inverting Frequency Response
Non-Inverting Frequency Response
RL = 150W to GND; unless specified)
Frequency Response vs. RL
225
0
Av = 10
-45
Av = 2
-90
Av = 4
-135
10
Av = -1
Av = -10
Av = -1
Av = -5
90
45
0
-225
-45
1
100
10
1
100
1k
-40
60
40
20
-80
0
-100
-20
0.001
100
-120
0.01
0.1
-80
3rd
RL = 1kΩ
3rd
RL = 150Ω
1
10
100
Frequency (MHz)
3rd Harmonic Distortion vs. Vout
-30
RL = 150Ω
-40
10MHz
-50
5MHz
-40
2MHz
-60
-70
1MHz
-80
0.1MHz
-50
Distortion (dBc)
Distortion (dBc)
2nd
RL = 1kΩ
-60
Phase
RL = 150Ω
-60
10MHz
5MHz
-60
2MHz
-70
-80
1MHz
-90
0.1MHz
-90
-100
0.1
-20
Gain
-30
-90
0
Frequency (MHz)
2nd
RL = 150Ω
100
80
2nd Harmonic Distortion vs. Vout
-50
-70
10
Open Loop Gain & Phase
10
Frequency (MHz)
Harmonic Distortion vs. Frequency
-135
100
CL = 10pF
Rs = 249Ω
250Ω
250Ω
10
-90
Frequency (MHz)
Rs
Vo = 1Vpp
Vo = 1Vpp
-45
RL = 150Ω
-225
CL = 1000pF
Rs = 22Ω
CL
0
RL = 75Ω
0
100
CL = 100pF
Rs = 54.9Ω
Magnitude (1dB/div)
Vo = 2Vpp
45
-180
Frequency Response vs. CL
Vo = 4Vpp
135
90
RL = 75Ω
RL = 1kΩ
Frequency (MHz)
Vo = 0.25Vpp
180
Phase (deg)
Magnitude (1dB/div)
135
-180
Frequency Response vs. Vout
Distortion (dBc)
180
Av = -2
Av = -10
Frequency (MHz)
1
Av = -2
Open Loop Gain (dB)
1
Magnitude (1dB/div)
Av = 10
Av = -5
RL = 1kΩ
RL = 150Ω
Phase (deg)
Av = 1
Vo = 0.25Vpp
Phase (deg)
Phase (deg)
Magnitude (1dB/div)
Av = 1
Rf = 0
Av = 2
Av = 4
Vo = 0.25Vpp
Magnitude (1dB/div)
Vo = 0.25Vpp
1
-100
0
10
1
2
3
4
0
Output Amplitude (Vpp)
Frequency (MHz)
Small Signal Pulse Response
1
2
3
4
Output Amplitude (Vpp)
Large Signal Pulse Response
Equivalent Input Noise
100
Voltage Noise (nV/Hz)
Output Voltage (0.5V/div)
Time (20ns/div)
Voltage = 9.5nV/√Hz
10
Current = 3.2pA/√Hz
1
0.001
Time (20ns/div)
10
Current Noise (pA/Hz)
Output Voltage (0.05V/div)
100
1
0.01
1
0.1
10
Frequency (MHz)
Differential Gain and Phase (3.58MHz)
IB, VIO, vs. Temperature
-10
1.7
PSRR, CMRR & Linear Rout vs. Frequency
2.5
2.5
25
100
-12
VIO
-16
0.9
-18
0.7
-20
Gain (%)
1.1
IB (µA)
IB
Phase Neg Sync
1.5
1.5
1
1
Gain Neg Sync
0.5
0.5
Phase (deg)
-14
1.3
VIO (mV)
2
2
80
20
CMRR
15
60
PSRR
40
10
5
20
Output Resistance (Ω)
1.5
PSRR, CMRR (dB)
RL tied to +2.5V
Rout
-22
0.5
-40
-20
0
20
40
Temperature (°C)
60
80
0
0
1
2
3
Number of 150Ω Loads
3
4
0
0.001
0
0.01
0.1
1
10
Frequency (MHz)
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CLC427 OPERATIONS
Description
The CLC427 contains two single supply voltage-feedback amplifiers. The CLC427 is a dual version of the
CLC423 with the following features:
+5V
6.8µF
+
3(5)
• 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 Vo = 4Vpp
Rb
+
2(6)
0.1µF
1/2
CLC427
-
Rg
Vin
8
4
Vo
1(7)
Rf
Rt
R
Vo
=− f
Vin
Rg
Select R t to yield
desired Rin = R t || R g
Figure 2: Inverting Configuration
Single Supply Operation (VCC = +5V, VEE = 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 (Vcm) of 2.5V. Vcm is the voltage around
which the inputs are applied and the output voltages are
specified.
Single Supply Operation for Inputs that go below 0V
Figures 3 and 4 show possible non-inverting and inverting 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 voltage divider biases the non-inverting input to VCC ÷ 2 =
2.5V.
Operating from a single +5V supply, the CMIR of the
CLC427 is typically 0V to +3.7V. The typical output range
with RL = 150Ω is +0.35V to +4.5V.
+5V
6.8µF
+
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.
Vin
R
Cc
3(5)
2.5V
R
Standard Single Supply Operation
Figures 1 and 2 show the recommended non-inverting
and inverting configurations for purely positive input
signals.
8
0.1µF
1/2
CLC427
-
4
1(7)
Rf
1
R
, where: Rin =
2πRinC c
2
R gC >> RC c
R >> Rsource
Figure 3: AC Coupled Non-inverting Configuration
+5V
+5V
6.8µF
6.8µF
+
+
2.5V
Vin
3(5)
Rt
2(6)
+
8
4
1(7)
Vo
Vin
3(5)
Cc
Rg
2(6)
+
8
0.1µF
1/2
CLC427
-
4
1(7)
Vo
Rf
R
Rf
 R 
Vo = Vin  − f  + 2.5
 Rg 
Rg
R
Vo
= 1+ f
Vin
Rg
low frequency cutoff =
1
2πR gC c
Figure 4: AC Coupled Inverting Configuration
Figure 1: Non-inverting Configuration
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R
0.1µF
1/2
CLC427
-
Vo
Rg
C
 R 
Vo = Vin 1+ f  + 2.5
 Rg 
low frequency cutoff =
2(6)
+
4
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 VEE. When the load is tied to VEE, the
output always sources current.
-40
Crosstalk (dB)
-50
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, VCC - VEE = 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.
-80
-100
1
10
100
Frequency (MHz)
Output Channel B (20mV/div)
Output Channel A (1V/div)
Figure 7: Input Referred Crosstalk vs. Frequency
Output Voltage (2V/div)
Input Voltage (4V/div)
-70
-90
Input
Output
-60
Channel A
Channel B
Time (50ns/div)
Figure 8: Pulsed crosstalk
Time (50ns/div)
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.
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.
Power Dissipation
The power dissipation of an amplifier can be described in
two conditions:
Magnitude (0.5dB/div)
Vout = 0.25Vpp
• Quiescent Power Dissipation PQ (No Load Condition)
Channel A
Channel B
• Total Power Dissipation PT (with Load Condition)
The following steps can be taken to determine the power
consumption for each CLC427 amplifier:
1
1. Determine the quiescent power
PQ = ICC (VCC – VEE)
2. Determine the RMS power at the output stage
PO = (VCC – Vload) (Iload)
3. Determine the total RMS power
PT = PQ + PO
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.
Add the total RMS powers for both channels to determine
the power dissipated by the dual.
5
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The maximum power that the package can dissipate at a
given temperature is illustrated in the Power Derating
curves in the Typical Performance section. The power
derating curve for any package can be derived by
utilizing the following equation:
+5V
6.8µF
+
5.1kΩ
3(5)
(175° − Tamb )
5.1kΩ
θ JA
Vin
where: Tamb = Ambient temperature (°C)
θJA = Thermal resistance, from junction to
ambient, for a given package (°C/W)
R2 =
R1 =
Layout Considerations
A proper printed circuit layout is essential for achieving
high frequency performance. Comlinear provides evaluation boards for the CLC427 (730038 - DIP, 730036SOIC) and suggests their use as a guide for high
frequency layout and as an aid for device testing and
characterization.
2(6)
R1
C
50Ω
390pF
Q
π fr c
fr = resonant frequency
R2
A = 2Q 2
4Q 2
+
8
0.1µF
1/2
CLC427
-
4
1(7)
Vo
R2
3.16kΩ
C
390pF
A = mid− band gain
Figure 9: Bandpass Filter Topology
40
30.6dB
940kHz
Magnitude (dB)
30
General layout and supply bypassing play major roles in
high frequency performance. Follow the steps below as
a basis for high frequency layout:
1. Include 6.8µF tantalum and 0.1µF ceramic
capacitors on both supplies.
2. Place the 6.8µF capacitors within 0.75 inches
of the power pins.
3. Place the 0.1µF capacitors within 0.1 inches
of the power pins.
4. Remove the ground plane under and around
the part, especially near the input and output
pins to reduce parasitic capacitance.
5. Minimize all trace lengths to reduce series
inductances.
20
10
0
-10
1
10
Frequency (MHz)
Figure 10: Bandpass Response
Distribution Amplifier
Figure 11 illustrates a distribution amplifier. The topology
utilizes the dual amplifier package. The input is
AC coupled and the non-inverting terminals of both
amplifiers are biased at 2.5V.
Additional information is included in the evaluation board
literature.
+5V
6.8µF
+
Applications Circuits
Vin
Typical Application Circuit
The typical application shown on the front page illustrates
the near rail-to-rail performance of the CLC427.
Ro
Multiple Feedback Bandpass Filter
Figure 9 illustrates a bandpass filter and design
equations. The circuit operates from a single supply of
+5V. The voltage divider biases the non-inverting input to
2.5V. The input is AC coupled to prevent the need for
level shifting the input signal at the source. Use the
design equations to determine R1 and R2 based on the
desired Q and center frequency.
R
3(5)
R
2(6)
+
8
0.1µF
1/2
CLC427
-
1(7)
Ro
Zo
Rf
Vo1
Ro
Rg
C
3(5)
2(6)
+
1/2
CLC427
-
4
1(7)
Ro
Zo
Rf
Rg
C
This example illustrates a bandpass filter with Q = 4 and
center frequency fc = 1MHz. Figure 10 indicates the
filter response.
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CC
Figure 11: Distribution Amplifier
6
Vo2
Ro
Ordering Information
DC Coupled Single-to-Differential Converter
A DC coupled single-to-differential converter is illustrated in
Figure 12.
Model
Temperature Range
Description
-40˚C to +85˚C
-40˚C to +85˚C
8-pin PDIP
8-pin SOIC
CLC427AJP
CLC427AJE
+5V
6.8µF
+
Vin
3(5)
Rt
2(6)
+
8
Package Thermal Resistance
Package
Plastic (AJP)
Surface Mount (AJE)
0.1µF
1/2
CLC427
1(7)
VH
(Av = +1V/V)
-
qJC
qJA
75˚/W
90˚/W
90˚/W
115˚/W
250Ω
2kΩ
3(5)
3kΩ
2(6)
Vo
+
1/2
CLC427
-
4
1(7)
VL
(Av = -1V/V)
250Ω
Vo = VH – VL
Vo = 2Vin
Figure 12: Single-to-Differential Converter
7
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Comlinear CLC427, Dual Voltage Feedback
Amplifier for Single Supply Operation
Customer Design Applications Support
National Semiconductor is committed to design excellence. For sales, literature and technical support, call the
National Semiconductor Customer Response Group at 1-800-272-9959 or fax 1-800-737-7018.
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of the president of National Semiconductor Corporation. As used herein:
1. Life support devices or systems are devices or systems which, a) are intended for surgical implant into the body, or b) support or
sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can
be reasonably expected to result in a significant injury to the user.
2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to
cause the failure of the life support device or system, or to affect its safety or effectiveness.
N
National Semiconductor
Corporation
National Semiconductor
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National Semiconductor
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Tel: 1(800) 272-9959
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circuitry and specifications.
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