CLC410AJP [ETC]
Current-Feedback Operational Amplifier ; 电流反馈运算放大器\n
| 型号： | CLC410AJP |
| 厂家： | 
ETC |
| 描述： | Current-Feedback Operational Amplifier
|
| 文件： | 总12页 (文件大小：323K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
February 2001
CLC410
Fast Settling, Video Op Amp with Disable
General Description
Features
n -3dB bandwidth of 200MHz
n 0.05% settling in 12ns
The current-feedback CLC410 is a fast settling, wideband,
monolithic op amp with fast disable/enable feature. De-
± ±
1 to 8), the
signed for low gain applications (AV
=
n Low Power, 160mW (40mW disabled)
n Low distortion, -60dBc at 20MHz
n Fast disable (200ns)
CLC410 consumes only 160mW of power (180mW max) yet
provides a -3dB bandwidth of 200MHz (AV = +2) and 0.05%
settling in 12ns (15ns max). Plus, the disable feature pro-
vides fast turn on (100ns) and turn off (200ns). In addition,
the CLC410 offers both high performance and stability with-
out compensation - even at a gain of +1.
n Differential gain/phase: 0.01%/0.01˚
±
±
1 to 8 closed-loop gain range
n
Applications
The CLC410 provides a simple, high performance solution
for video switching and distribution applications, especially
where analog buses benefit from use of the disable function
to “multiplex” signals onto the bus. Differential gain/phase of
0.01%/0.01˚ provide high fidelity and the 60mA output cur-
rent offers ample drive capability.
n Video switching and distribution
n Analog bus driving (with disable)
n Low power “standby” using Disable
n Fast, precision A/D conversion
n D/A current-to-voltage conversion
n IF processors
The CLC410’s fast settling, low distortion, and high drive
capabilities make it an ideal ADC driver. The low 160mW
quiescent power consumption and very low 40mW disabled
power consumption suggest use where power is critical
and/or “system off” power consumption must be minimized.
n High speed communications
Enable/Disable Response
The CLC410 is available in several versions to meet a
variety of requirements. A three letter suffix determines the
version.
Enhanced Solutions (Military/Aerospace)
SMD Number: 5962-90600
Space level versions also available.
For more information, visit http://www.national.com/mil
DS012749-10
Connection Diagram
DS012749-21
Pinout
DIP & SOIC
© 2001 National Semiconductor Corporation
DS012749
www.national.com
Connection Diagram (Continued)
DS012749-1
Non-Inverting Frequency Response
Ordering Information
Package
Temperature Range
Industrial
Part Number
Package
Marking
NSC
Drawing
N08A
8-pin plastic DIP
−40˚C to +85˚C
−40˚C to +85˚C
CLC410AJP
CLC410AJE
CLC410AJP
CLC410AJE
8-pin plastic SOIC
M08A
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2
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Junction Temperature
+150˚C
−40˚C to +85˚C
−65˚C to +150˚C
10 sec
Operating Temperature Range
Storage Temperature Range
Lead Solder Duration (+300˚C)
ESD Rating (human body model)
500V
±
7V
Supply Voltage (VCC
IOUT
)
Operating Ratings
Thermal Resistance
Output is short circuit protected to
ground, but maximum reliability will
be maintained if IOUT does not
exceed...
60mA
Package
MDIP
(θJC
)
(θJA)
±
Common Mode Input Voltage
Differential Input Voltage
VCC
5V
65˚C/W
60˚C/W
120˚C/W
140˚C/W
SOIC
±
Disable Input Voltage (pin 8)
Applied output voltage when disabled
VCC−1V
±
VCC
Electrical Characteristics
±
5V, RL = 100Ω, Rf = 250Ω; unless specified
AV = +2, VCC
=
Symbol
Parameter
Conditions
Typ
Max/Min (Note 2)
Units
Ambient Temperature
CLC410AJ
+25˚C
−40˚C
+25˚C
+85˚C
Frequency Domain Response
<
>
>
>
>
>
>
35
SSBW
LSBW
-3dB Bandwidth
VOUT 0.5VPP
200
50
150
150
120
MHz
MHz
<
VOUT 5VPP, AV
=
35
35
+5
<
Gain Flatness
Peaking
VOUT 0.5VPP
<
<
<
<
<
<
<
<
<
<
GFPL
GFPH
GFR
DC to 40MHz
0
0.4
0.7
0.3
0.5
0.4
0.7
1.3
1.2
dB
dB
>
Peaking
40MHz
0
Rolloff
DC to 75MHz
DC to 75MHz
0.6
0.2
1
1
1
1
dB
<
<
LPD
linear phase deviation
deg
Time Domain Response
<
<
<
TRS
TRL
TSP
TS
Rise and Fall Time
0.5V Step
5V Step
2V Step
2V Step
0.5V Step
1.6
6.5
10
2.4
2.4
2.4
ns
ns
<
<
<
<
<
<
<
<
<
<
<
<
10
13
15
15
10
13
15
10
10
13
15
10
±
±
Settling Time to
0.1%
ns
0.05%
12
ns
OS
Overshoot
Slew Rate
0
%
>
>
>
SR
AV = +2
AV = −2
700
1600
430
–
430
–
430
–
V/µs
V/µs
SR1
Distortion And Noise Response
<
<
<
<
<
<
HD2
HD3
2nd Harmonic Distortion
3rd harmonic distortion
Equivalent Input Noise
Noise Floor
2VPP, 20MHz
2VPP, 20MHz
−60
−60
−40
−50
−45
−50
−45
−50
dBc
dBc
>
<
<
<
−153
SNF
INV
1MHz (Note 4)
−157
40
−154
−154
dBm
(1Hz)
<
<
<
63
Integrated Noise
1MHz to 200MHz
(Note 4)
54
57
µV
DG
DP
Differential Gain (Note 5)
Differential Phase (Note 5)
(See Plots)
(See Plots)
0.01
0.01
0.05
0.1
0.04
0.02
0.04
0.02
%
deg
Disable/Enable Performance
>
<
<
<
1000
TOFF
Disable Time to 50dB
200
100
1000
1000
ns
ns
Attenuation at 10MHz
Enable Time
DIS Voltage
<
<
<
200
TON
200
200
VDIS
VEN
To Disable
1.0
2.6
0.5
2.3
0.5
3.2
0.5
4.0
V
V
To Enable
3
www.national.com
Electrical Characteristics (Continued)
±
5V, RL = 100Ω, Rf = 250Ω; unless specified
AV = +2, VCC
=
Symbol Parameter
Conditions
Typ
Max/Min (Note 2)
Units
Disable/Enable Performance
DIS current (sourced
from CLC410, see Figure 5)
IDIS
IEN
To Disable
200
80
250
60
250
60
250
60
µA
µA
dB
To Enable
>
>
>
55
OSD
Off Isolation
At 10MHz
59
55
55
Static, DC Performance
<
<
<
<
<
±
9.0
±
±
VIO
Input Offset Voltage (Note 3)
2
20
10
100
10
50
50
50
16
4
8.2
5.0
mV
µV/˚C
µA
<
<
±
±
DVIO
IBN
average temperature coefficient
Input Bias Current (Note 3)
Average Temperature Coefficient
Input Bias Current (Note 3)
Average Temperature Coefficient
Power Supply Rejection Ratio
Common Mode Rejection Ratio
Supply Current (Note 3)
40
36
–
40
20
<
<
±
±
±
Non Inverting
Inverting
20
<
<
±
100
±
DIBN
IBI
200
–
nA/˚C
µA
<
<
±
±
±
36
200
45
20
30
100
45
<
<
±
±
DIBI
PSRR
CMRR
ICC
–
nA/˚C
dB
>
>
<
>
>
<
>
>
<
45
45
18
45
45
dB
No Load,Quiescent
No Load,Quiescent
18
18
mA
<
<
<
6
ISD
Supply Current, Disabled
6
6
mA
Miscellaneous Performance
>
<
>
<
<
<
>
<
<
<
RIN
Non-Inverting Input
Resistance
200
0.5
0.1
200
0.5
50
100
100
kΩ
pF
Ω
<
<
CIN
Capacitance
At DC
2
2
2
<
RO
Output Impedance
0.2
100
0.2
100
0.2
100
<
ROD
COD
VO
Output Impedance, Disabled
Resistance,at DC
Capacitance,at DC
No Load
kΩ
pF
V
<
>
2
2
2
>
>
±
3.2
>
±
±
±
±
±
Output Voltage Range
3.5
2.1
3
3.2
>
>
±
±
CMIR
Common Mode Input Range
For Rated
1.2
2
2
V
Performance
>
>
>
>
>
>
±
±
±
±
±
±
±
IO
IO
Output Current
−40˚C to +85˚C
−55˚C to +125˚C
70
60
30
30
50
50
50
50
mA
mA
±
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, sample at 85˚C.
Note 4: Noise tests are performed from 5MHz to 200MHz.
Note 5: Differential gain and phase measured at: A = +2, R = 250Ω, R = 150Ω 1V equivalent video signal, 0-100 IRE, 40 IRE , 3.58 MHz,) IRE =0 volts, at
V
f
L
PP
PP
75Ω load. See text.
www.national.com
4
±
5V, RL = 100Ω; Unless Specified).
Typical Performance Characteristics (TA = 25˚, AV = +2, VCC
=
Non-Inverting Frequency Response
Inverting Frequency Response
DS012749-1
DS012749-2
Frequency Response for Various RLS
Forward and Reverse Gain During Disable
DS012749-3
DS012749-4
2nd and 3rd Harmonic Distortion
2-Tone, 3rd Order, Intermodulation Intercept
DS012749-6
DS012749-5
5
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±
Typical Performance Characteristics (TA = 25˚, AV = +2, VCC
=
5V, RL = 100Ω; Unless
Specified).. (Continued)
Equivalent Input Noise
CMRR and PSRR
DS012749-7
DS012749-8
Pulse Response
Settling Time
DS012749-28
DS012749-23
Long-Term Settling Time
Settling Time vs. Capacitive Load
DS012749-9
DS012749-24
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6
±
5V, RL = 100Ω; Unless
Typical Performance Characteristics (TA = 25˚, AV = +2, VCC
=
Specified).. (Continued)
Enable/Disable Response
Differential Gain and Phase (3.58MHz)
DS012749-10
DS012749-11
Differential Gain and Phase (4.43MHz)
DS012749-12
Application Division
DS012749-13
FIGURE 1. Recommended Non-Inverting Gain Circuit
7
www.national.com
Application Division (Continued)
DS012749-14
FIGURE 2. Recommended Inverting Gain Circuit
Enable/Disable Operation
The CLC410 has an enable/disable feature that is useful for
conserving power and for multiplexing the outputs of several
amplifiers onto an analog bus (Figure 3). Disabling an am-
plifier while not in use reduces power supply current and the
output and inverting input pins become a high impedance.
DS012749-16
FIGURE 4.
Pin 8, the DIS pin, can be driven from either open-collector
TTL or from 5V CMOS. A logic low disables the amplifier and
an internal 15kΩ pull-up resistor ensures that the amplifier is
enabled if pin 8 is not connected (Figure 5). Both TTL and 5V
CMOS logic are guaranteed to drive
a high enough
high-level output voltage (VOH) to ensure that the CLC410 is
enabled. Whichever type used, “break-before-make” opera-
tion should be established when outputs of several amplifi-
ers are connected together. This is important for avoiding
large, transient currents flowing between amplifiers when
two or more are simultaneously enabled. Typically, proper
operation is ensured if all the amplifiers are driven from the
same decoder integrated circuit because logic output rise
times tend to be longer than fall times. As a result, the
DS012749-15
FIGURE 3.
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8
Application Division (Continued)
amplifier being disabled will reach the 2V threshold sooner
than the amplifier being enabled (see tD of Figure 4 timing
diagram).
DS012749-19
Open-Loop Transimpedance Gain, Z(s)
Developing the non-inverting frequency response for the
topology of Figure 3 yields:
DS012749-17
FIGURE 5. Equivalent of (not) DIS input
During disable, supply current drops to approximately 4mA
and the inverting input and output pin impedances become
200kΩ\ 0.5pF each. The total impedance that a disabled
amplifier and its associated feedback network presents to
the analog bus is determined from Figure 6. For example, at
a non-inverting gain of 1, the output impedance at video
frequencies is 100kΩ\ 1pF since the 250Ω feedback resistor
is a negligible impedance. Similarly, output impedance is
(1)
where LG is the loop gain defined by,
500Ω\ 0.5pF at a non-inverting gain of 2 (with Rf = Rg
250Ω).
=
(2)
Equation 1 has a form identical to that for a voltage feedback
amplifier with the differences occurring in the LG expression,
eq.2. For an idealized treatment, set Zi = 0 which results in a
very simple LG=Z(s)/Rf (Derivation of the transfer function
for the case where Zi = 0 is given in Application Note
AN300-1). Using the Z(s) (open-loop transimpedance gain)
plot shown on the previous page and dividing by the recom-
mended Rf = 250Ω, yields a large loop gain at DC. As a
result, Equation 1 shows that the closed-loop gain at DC is
very close to (1+Rf/Rg).
DS012749-18
FIGURE 6.
Differential Gain and Phase
Plots on the preceding page illustrate the differential gain
and phase performance of the CLC410 at both 3.58MHz and
4.43MHz. Application Note OA-08 presents a measurement
technique for measuring the very low differential gain and
phase of the CLC410. Observe that the gain and phase
errors remain low even as the output loading increases,
making the device attractive for driving multiple video out-
puts.
DS012749-20
Understanding the Loop Gain
FIGURE 7. Current Feedback Topology
The CLC410 is a current-feedback op amp. Referring to the
equivalent circuit of Figure 7, any current flowing in the
inverting input is amplified to a voltage at the output through
the transimpedance gain shown below. This Z(s) is analo-
gous to the open-loop gain of a voltage feedback amplifier.
At higher frequencies, the roll-off of Z(s) determines the
closed-loop frequency response which, ideally, is dependent
only on Rf. The specifications reported on the previous
pages are therefore valid only for the specified Rf
=
250Ω. Increasing Rf from 250Ω will decrease the loop gain
and band width, while decreasing it will increase the loop
gain possibly leading to inadequate phase margin and
9
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DC operation. Output noise is determined similarly except
that a root-sum-of-squares replaces the algebraic sum. Rs is
the non-inverting pin resistance.
Application Division (Continued)
closed-loop peaking. Conversely, fixing Rf will hold the fre-
quency response constant while the closed-loop gain can be
adjusted using Rg.
Equation 4
±
±
Output Offset VO= IBNx RS(1+Rf/Rg)
The CLC410 departs from this idealized analysis to the
extent that the inverting input impedance is finite. With the
low quiescent power of the CLC410, Zi)50Ω leading to drop
in loop gain and bandwidth at high gain settlings, as given by
equation 2. The second term in Equation 2 accounts for the
division in feedback current that occurs between Zi and
RfiRg at the inverting node of the CLC410. This decrease in
bandwidth can be circumvented as described in “Increasing
Bandwidth at High Gains.” Also see “Current Feedback Am-
plifiers” in the National Databook for a thorough discussion
of current feedback op amps.
±
VIO (1+Rf/Rg) IBIx Rf
An important observation is that for fixed Rf, offsets as
referred to the input improve as the gain is increased (divide
all terms by 1+Rf/Rg). A similar result is obtained for noise
where noise figure improves as a gain increases.
The input noise plot shown in the CLC400 datasheet applies
equally as well to the CLC410.
Capacitive Feedback
Capacitive feedback should not be used with the CLC410
because of the potential for loop instability. See Application
Note OA-7 for active filter realizations with the CLC410.
Increasing Bandwidth At High Gains
Bandwidth may be increased at high closed-loop gains by
adjusting Rf and Rg to make up for the losses in loop gain
that occur at these high gain settlings due to current division
at the inverting input. An approximate relationship may be
obtained by holding the LG expression constant as the gain
is changed from the design point used in the specifications
(that is, Rf = 250Ω and Rg = 250Ω). For the CLC400 this
gives,
Offset Adjustment Pin
Pin 1 can be connected to a potentiometer as shown in
Figure 1 and used to adjust the input offset of the CLC410.
Full range adjustment of 5V on pin 1 will yield a 10mV
input offset adjustment range. Pin 1 should always be by-
passed to ground with a ceramic capacitor located close to
the package for best settling performance.
±
±
Printed Circuit Layout
As with any high frequency device, a good PCB layout will
enhance performance. Ground plane construction and good
power supply bypassing close to the package are critical to
achieving full performance. In the non-inverting configura-
tion, the amplifier is sensitive to stray capacitance to ground
at the inverting input. Hence, the inverting node connections
should be small with minimal coupling to the ground plane.
Shunt capacitance across the feedback resistor should not
be used to compensate for this effect.
Parasitic or load capacitance directly on the output will intro-
duce additional phase shift in the loop degrading the loop
phase margin and leading to frequency response peaking. A
small series resistor before the capacitance effectively de-
couples this effect. The graphs on the preceding page illus-
trates the required resistor value and resulting performance
vs. capacitance.
(3)
where AVis the non-inverting gain. Note that with AV = +2 we
get the specified Rf = 250Ω, while at higher gains, a lower
value gives stable performance with improved bandwidth.
Precision buffed resistors (PRP8351 series from Precision
Resistive Products) with low parasitic reactances were used
to develop the data sheet specifications. Precision carbon
composition resistors will also yield excellent results. Stan-
dard spirally-trimmed RN55D metal film resistors will work
with a slight decrease in bandwidth due to their reactive
nature at high frequencies.
DC Accuracy and Noise
Since the two inputs for the CLC410 are quite dissimilar, the
noise and offset error performance differs somewhat from
that of a standard differential input amplifier. Specifically, the
inverting input current noise is much larger than the
non-inverting current noise. Also the two input bias currents
are physically unrelated rendering bias current cancellation
through matching of the inverting and non-inverting pin re-
sistors ineffective.
Evaluation PC boards (part no. 730013 for through-hole and
730027 for SOIC) for the CLC404 are available.
In Equation 4, the output offset is the algebraic sum of the
equivalent input voltage and current sources that influence
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10
Physical Dimensions inches (millimeters) unless otherwise noted
8-Pin SOIC
NS Package Number M08A
11
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
8-Pin MDIP
NS Package Number N08E
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