www.fairchildsemi.com
KH207
Low Distortion Wideband Op Amp
Features
s
s
s
s
s
s
s
s
General Description
The KH207 is a wideband, low distortion operational
amplifier designed specifically for applications requiring
both high speed and wide dynamic range. Utilizing
a proprietary current feedback architecture, the
KH207 offers performance far superior to that of
conventional voltage feedback op amps.
The most attractive feature of the KH207 is its
extremely low distortion: -80/-85dBc 2nd/3rd harmonics
at 20MHz (2V
pp
, R
L
= 200Ω). The KH207 also provides
-3dB bandwidth of 170MHz at a gain of +20, settles to
0.1% in 22ns and slews at a rate of 2400V/µs. The
combination of these features positions the KH207 as
the right choice for high speed applications requiring
exceptional signal purity.
High speed, high resolution A/D and D/A converter
systems requiring low distortion operation will find
the KH207 an excellent choice. Wide dynamic range
systems such as radar and communication receivers
will find that the KH207’s low harmonic distortion and
low noise make it an attractive high speed solution.
The addition of the KH207 to the KH205/206 Series
of high speed operational amplifiers broadens the
selection of features available from which to choose.
The KH205 offers low power operation, the KH206
offers higher drive operation, and the KH207 offers
operation with extremely low distortion, all of which
are pin compatible and overdrive protected.
The KH207 is constructed using thin film resistor/bipolar
transistor technology, and is available in the following
versions:
KH207AI
KH207AK
Supply
Voltage
-V
CC
10
9
Collector
Supply
Output
-80/-85dBc 2nd/3rd HD at 20MHz
-3dB bandwidth of 170MHz
0.1% settling in 22ns
Complete overdrive protection
2400V/µs slew rate
3MΩ input resistance
Output may be current limited
Direct replacement for CLC207
Applications
s
s
s
s
s
s
Fast, precision A/D conversion
Automatic test equipment
Input/output amplifiers
Photodiode, CCD preamps
High-speed modems, radios
Line drivers
Bottom View
Internal
Feedback
Case
ground
GND
7
R
f
8
-V
CC
-25°C to +85°C
-55°C to +125°C
-55°C to +125°C
KH207AM
2000Ω
Non-Inverting
Input
Inverting
Input
Not
Connected
V+ 6
+
V- 5
NC 4
3
2
NC
6
6
-
11 V
o
12
+V
CC
Collector
Supply
KH207HXC
KH207HXA
-55°C to +125°C
-55°C to +125°C
12-pin TO-8 can
12-pin TO-8 can, features
burn-in & hermetic testing
12-pin TO-8 can,
environmentally
screened and electrically
tested to MIL-STD-883
SMD#: 5962-9097701HXC
SMD#: 5962-9097701HXA
1
+V
CC
Supply
Voltage
Case and
bias ground
GND
Typical Performance
Gain Setting
Parameter
+7
+20 +50
-1
-20 -50
Units
MHz
ns
V/ns
ns
-3dB bandwidth
220 170 80 220 130 80
rise time
1.7 2.2 4.7 1.7 2.9 4.7
slew rate
2.4 2.4 2.4 2.4 2.4 2.4
settling time (to 0.1%) 22 22 20 21 20 19
Not Connected
Pin 8 provides access to a 2000Ω feed-
back resistor which can be connected to
the output or left open if an external feed-
back resistor is desired.
REV. 1A February 2001
DATA SHEET
KH207
KH207 Electrical Characteristics
PARAMETERS
Ambient Temperature
Ambient Temperature
FREQUENCY DOMAIN RESPONSE
✝
-3dB bandwidth
large-signal bandwidth
gain flatness
✝
peaking
✝
peaking
✝
rolloff
group delay
linear phase deviation
TIME DOMAIN RESPONSE
rise and fall time
settling time to 0.1%
to 0.05%
overshoot
slew rate
KH207AI
(A
v
= +20V, V
CC
= ±15V, R
L
= 200Ω, R
f
= 2kΩ; unless specified)
TYP
+25°C
+25°C
170
100
0
0
–
3.0 ± .2
0.8
2.2
4.8
22
24
7
2.4
-80
-69
-85
-69
1.6
20
2.2
-158
33
33
3.5
11
3.0
15
2.0
20
69
60
25
3.0
5.0
–
±12
2.0
–
–
2.2
MIN & MAX RATINGS
-25°C
-55°C
>140
>72
<0.3
<0.8
<0.8
–
<3.0
<2.6
<5.5
<27
<30
<14
>1.8
<-68
<-64
<-76
<-64
<1.8
<23
<2.5
<-157
<38
<38
<8.0
<25
<25
<100
<22
<150
>55
>50
<27
>1.0
<7.0
<0.1
>±11
–
–
–
<3.0
+25°C
+25°C
>140
>80
<0.3
<0.5
<0.8
–
<2.0
<2.6
<5.5
<27
<30
<14
>2.0
<-76
<-64
<-76
<-64
<1.8
<23
<2.5
<-157
<38
<38
<8.0
<25
<15
<100
<10
<150
>55
>50
<27
>1.0
<7.0
<0.1
>±11
–
<0.2
-100 ±40
<3.0
+85°C
+125°C
>125
>80
<0.5
<0.8
<0.8
–
<3.0
<3.0
<5.5
<27
<30
<14
>2.0
<-76
<-64
<-76
<-64
<1.8
<23
<2.5
<-157
<38
<38
<11.0
<25
<15
<100
<25
<150
>55
>50
<29
>1.0
<7.0
<0.1
>±11
–
–
–
<3.2
MHz
MHz
dB
dB
dB
ns
°
ns
ns
ns
ns
%
V/ns
dBc
dBc
dBc
dBc
SSBW
FPBW
GFPL
GFPH
GFR
GD
LPD
TRS
TRL
TS
TSP
OS
SR
HD2
HD2
HD3
HD3
UNITS
SYM
CONDITIONS
KH207AK/AM/HXC/HXA
V
o
<2V
pp
V
o
<10V
pp
V
o
<2V
pp
0.1 to 35MHz
>35MHz
at 70MHz
to 70MHz
to 50MHz
2V step
10V step
10V step, note 2
10V step, note 2
5V step
20V
pp
at 50MHz
NOISE AND DISTORTION RESPONSE
✝
2nd harmonic distortion
✝
2V
pp
, 20MHz, R
L
= 200Ω
2V
pp
, 20MHz, R
L
= 100Ω
✝
3rd harmonic distortion
✝
2V
pp
, 20MHz, R
L
= 200Ω
2V
pp
, 20MHz, R
L
= 100Ω
equivalent input noise
voltage
>100kHz
inverting current
>100kHz
non-inverting current
>100kHz
noise floor
>100kHz
integrated noise
1kHz to 150MHz
integrated noise
5MHz to 150MHz
STATIC, DC PERFORMANCE
* input offset voltage
average temperature coefficient
* input bias current
average temperature coefficient
* input bias current
average temperature coefficient
* power supply rejection ratio
common mode rejection ratio
* supply current
MISCELLANEOUS PERFORMANCE
non-inverting input resistance
non-inverting input capacitance
output impedance
output voltage range
internal feedback resistor
absolute tolerance
temperature coefficient
inverting input current self limit
VN
nV/√Hz
ICN
pA/√Hz
pA/√Hz NCN
dBm(1Hz) SNF
µV
INV
µV
INV
mV
µV/°C
µA
nA/°C
µA
nA/°C
dB
dB
mA
MΩ
pF
Ω
V
kΩ
%
ppm/°C
mA
VIO
DVIO
IBN
DIBN
IBI
DIBI
PSRR
CMRR
ICC
RIN
CIN
RO
VO
RF
RFA
RFTC
ICL
non-inverting
inverting
no load
DC
70MHz
DC
no load
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
V
CC
I
o
common mode input voltage, V
o
differential input voltage
thermal resistance
junction temperature
operating temperature
storage temperature
lead temperature (soldering 10s)
±20V
±150mA
|V
CC
| > 15V ±(29 - |V
CC
|)V
|V
CC
|
≤
15V ±(|V
CC
| -1)V
±3V
(see thermal model)
+175°C
AI: -25°C to +85°C
AK/AM/HXC/HXA: -55°C to +125°C
-65°C to +150°C
+300°C
Recommended Operating Conditions
V
CC
±5V to ±15V
I
o
±100mA
common mode input voltage
±(|V
CC
| -5)V
gain range
+7 to +50, -1 to -50
note 1:
* AI/AK/AM/HXC/HXA 100% tested at +25°C
✝
AK/AM/HXC/HXA
100% tested at +25°C and sample
tested at -55°C and +125°C
✝
AI
sample tested at +25°C
note 2:
Settling time specifications require the use of an external
feedback resistor (2kΩ).
2
REV. 1A February 2001
KH207
DATA SHEET
KH207 Typical Performance Characteristics
(T
A
= +25°C, A
v
= +20, V
CC
= ±15V, R
f
= 20Ω, R
L
= 200Ω; unless specified)
Non-Inverting Frequency Response
Normalized Magnitude (1dB/div)
Normalized Magnitude (1dB/div)
Inverting Frequency Response
Frequency Response vs. External R
f
A
v
= +50
R
f
= 1.5kΩ
R
f
= 2kΩ
R
f
= 3kΩ
R
f
= 1.5kΩ
A
v
= +20
R
f
= 3kΩ
R
f
= 2kΩ
Gain
A
v
= +20
A
v
= +50
Phase
A
v
= +50
A
v
= +20
A
v
= +7
A
v
= -7
Phase
A
v
= -50
A
v
= -20
A
v
= -7
A
v
= -50
A
v
= -20
A
v
= -1
Relative Gain (5dB/div)
A
v
= +7
Gain
A
v
= -1
Phase (45°/div)
Phase (45°/div)
R
f
= 1.5kΩ
R
f
= 2kΩ
A
v
= +7
R
f
= 3kΩ
0
20
40
60
80 100 120 140 160 180 200
0
20
40
60
80 100 120 140 160 180 200
0
20
40
60
80 100 120 140 160 180 200
Frequency (MHz)
Large Signal Gain and Phase
V
o
= 10V
pp
Frequency (MHz)
Relative Bandwidth vs. V
CC
1.0
0.9
Gain
Frequency (MHz)
Gain and Phase for Various Loads
R
L
= 50Ω
R
L
= 100Ω
R
L
= 200Ω
R
L
= 1kΩ
Magnitude (1dB/div)
Gain
0.8
0.7
0.6
0.5
0.4
0.3
0.2
Magnitude (1dB/div)
Relative Bandwidth
Phase (45°/div)
Phase (45°/div)
Phase
Phase
R
L
= 1kΩ
R
L
= 200Ω
R
L
= 100Ω
R
L
= 50Ω
0
15
30
45
60
75
90 105 120 135 150
4
6
8
10
12
14
16
0
20
40
60
80 100 120 140 160 180 200
Frequency (MHz)
Small Signal Pulse Response
Output Voltage (0.4V/div)
±V
CC
(V)
Large Signal Pulse Response
0.20
A
v
= +20
Frequency (MHz)
Settling Time
0.15
10V step
R
f
= 2kΩ (external)
Output Voltage (2V/div)
A
v
= +20
Settling Error (%)
A
v
= -20
0.10
0.05
0
-0.05
-0.10
-0.15
-0.20
A
v
= -20
Time (5ns/div)
Time (5ns/div)
Time (5ns/div)
2nd and 3rd Harmonic Distortion
-40
-45
-50
-20
-30
2nd Harmonic Distortion, R
L
= 100Ω
-20
-30
3rd Harmonic Distortion, R
L
= 100Ω
16V
pp
Distortion (dBc)
Distortion (dBc)
-55
-60
-65
-70
-75
-80
-85
-90
1
10
-40
-50
-60
Distortion (dBc)
16V
pp
8V
pp
-40
8V
pp
2nd
4V
pp
-50
-60
2V
pp
4V
pp
-70
-80
-90
1V
pp
2V
pp
-70
-80
1V
pp
3rd
-90
1
10
100
1
10
100
100
Frequency (MHz)
CMRR and PSRR
100
45
Frequency (MHz)
2-Tone, 3rd Order Intermod. Intercept
100
50Ω
P
out
Frequency (MHz)
Equivalent Input Noise
100
Noise Voltage (nV√Hz)
PSRR and CMRR (dB)
80
PSRR
Interdept Point (dBm)
40
35
30
25
20
15
Noise Current (pA√Hz)
50Ω
Inverting Current 20pA√Hz
60
40
20
0
CMRR
10
10
Non-Inverting Current 2.2pA√Hz
Voltage 1.6nV/√Hz
1
0
10
20
30
40
50
60
70
80
90 100
10
2
10
3
10
4
10
5
10
6
10
7
10
8
1
100
1k
10k
100k
1M
10M
100M
Frequency (Hz)
Frequency (MHz)
Frequency (Hz)
REV. 1A February 2001
3
DATA SHEET
KH207
Current Feedback Amplifiers
Some of the key features of current feedback technology
are:
s
Independence of AC bandwidth and voltage gain
s
Adjustable frequency response with feedback resistor
s
High slew rate
s
Fast settling
Current feedback operation can be described using a simple
equation. The voltage gain for a non-inverting or inverting
current feedback amplifier is approximated by Equation 1.
V
o
A
v
=
V
in
1
+
R
f
Z
(
j
ω
)
where:
s
s
s
Short Circuit Protection
Damage caused by short circuits at the output may be
prevented by limiting the output current to safe levels.
The most simple current limit circuit calls for placing
resistors between the output stage collector supplies and
the output stage collectors (pins 12 and 10). The value of
this resistor is determined by:
R
C
=
V
C
−
R
I
I
I
Equation 1
where I
I
is the desired limit current and R
I
is the minimum
expected load resistance (0Ω for a short to ground).
Bypass capacitors of 0.01µF on should be used on the
collectors as in Figures 2 and 3.
+15V
3.9
33Ω
.1
6
1
12
8
10
3,7
9
11
A
v
is the closed loop DC voltage gain
R
f
is the feedback resistor
Z(jω) is the CLC205’s open loop transimpedance
gain
Z
(
j
ω
)
is the loop gain
R
f
Capactance in
µF
.01
V
in
R
i
50Ω
R
g
+
-
s
KH207
5
V
o
200Ω
The denominator of Equation 1 is approximately equal to
1 at low frequencies. Near the -3dB corner frequency, the
interaction between R
f
and Z(jω) dominates the circuit
performance. The value of the feedback resistor has a
large affect on the circuits performance. Increasing R
f
has the following affects:
s
s
s
s
s
-15V
3.9
.1
33Ω
.01
R
f
R
g
R
f
= 2000Ω (internal)
A
v
=
1
+
Decreases loop gain
Decreases bandwidth
Reduces gain peaking
Lowers pulse response overshoot
Affects frequency response phase linearity
Figure 2: Recommended Non-Inverting Gain Circuit
33Ω
.1
50Ω
6
1
12
8
10
3,7
9
11
+15V
3.9
Capactance in
µF
.01
Overdrive Protection
Unlike most other high-speed op amps, the KH207 is not
damaged by saturation caused by overdriving input
signals (where V
in
x gain > max. V
o
). The KH207 self
limits the current at the inverting input when the output is
saturated (see the inverting input current self limit
specification); this ensures that the amplifier will not be
damaged due to excessive internal currents during overdrive.
For protection against input signals which would exceed
either the maximum differential or common mode input
voltage, the diode clamp circuits below may be used.
differential protection
V
in
+
-
V
in
R
i
-15V
R
g
5
KH207
V
o
200Ω
33Ω
3.9
.1
.01
A
v
=
-R
f
R
g
R
f
= 2000Ω (internal)
For Z
in
= 50Ω, select R
g
||R
i
= 50Ω
Figure 3: Recommended Inverting Gain Circuit
A more sophisticated current limit circuit which provides
a limit current independent of R
I
is shown in Figure 4 on
page 5.
With the component values indicated, current limiting
occurs at 50mA. For other values of current limit (I
I
),
select R
C
to equal V
be
/l
I
. Where V
be
is the base to
emitter voltage drop of Q3 (or Q4) at a current of [2V
CC
–
1.4] / R
x
, where R
x
≤
[(2V
CC
– 1.4) / I
I
] B
min
.
Also, B
min
is the minimum beta of Q1 (or Q2) at a current
of I
I
. Since the limit current depends on V
be
, which is
temperature dependent, the limit current is likewise
temperature dependent.
REV. 1A February 2001
+
KH207
V
o
-V
cc
R
g
+V
cc
-
common mode
protection
Figure 1: Diode Clamp Circuits for Common Mode
and Differential Mode Protection
4
KH207
+V
cc
R
c
12Ω
Q1
(MJE170)
0.01ΩF
DATA SHEET
Q3
(2N3906)
Noise Analysis
Approximate noise figure can be determined for the
KH207 using the
Equivalent Input Noise
plot on page 3
and the equations shown below.
kT = 4.00 x 10
-21
Joules at 290°K
V
n
is spot noise voltage (V/√Hz)
i
n
is non-inverting spot noise current (A/√Hz)
i
i
is inverting spot noise current (A/√Hz)
to pin 12
to pin 10
0.01ΩF
R
x
14.3kΩ
R
s
Q2
(MJE180)
R
c
12Ω
-V
cc
Q4
(2N3904)
+
R
n
KH207
R
o
-
R
f
R
g
Figure 4: Active Current Limit Circuit (50mA)
Controlling Bandwidth and Passband Response
In most applications, a feedback resistor value of 2kΩ
will provide optimum performance; nonetheless, some
applications may require a resistor of some other value.
The response versus R
f
plot on the previous page shows
how decreasing R
f
will increase bandwidth (and frequency
response peaking, which may lead to instability).
Conversely, large values of feedback resistance tend to
roll off the response.
The best settling time performance requires the use of an
external feedback resistor (use of the internal resistor
results in a 0.1% to 0.2% settling tail). The settling
performance may be improved slightly by adding a
capacitance of 0.4pF in parallel with the feedback
resistor (settling time specifications reflect performance
with an external feedback resistor but with no external
capacitance).
Thermal Model
T
case
100°C/W
T
j(pnp)
P
pnp
100°C/W
T
j(npn)
P
npn
17.5
°
C/W
T
j(circuit)
P
circuit
+
-
T
ambient
θ
ca
2
R
2
i
i2
R
s
R
s
2
V
n
f
F
=
10 log
1
+
+
⋅
i
n
+
+
2
2
R
n
4 kT
R
p
R
p
A
2
v
where R
p
=
R
s
R
n
R
s
+
R
n
;
A
v
=
R
f
R
g
+
1
Figure 5: Noise Figure Diagram and Equations
(Noise Figure is for the Network Inside this Box.)
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 KH207 will
improve stability and settling performance.
Transmission Line Matching
One method for matching the characteristic impedance
(Z
o
) of a transmission line or cable is to place the
appropriate resistor at the input or output of the amplifier.
Figure 6 shows typical inverting and non-inverting circuit
configurations for matching transmission lines.
Z
0
C
6
+
R
1
V
1
+
-
R
4
V
2
+
-
R
3
R
2
Z
0
R
6
KH207
-
V
o
R
7
Z
0
R
g
R
5
R
f
P
circuit
= [(+V
CC
) – (-V
CC
)]
2
/ 1.77kΩ
P
xxx
= [(±V
CC
) – V
out
– (I
col
) (R
col
+ 6)] (I
col
)
(% duty cycle)
(For positive V
o
and V
CC
, this is the power in the npn output stage.)
(For negative V
o
and V
CC
, this is the power in the pnp output stage.)
θ
ca
= 65°C/W in still air without a heatsink.
35°C/W in still air without a Thermalloy 2268.
15°C/W in 300ft/min air with a Thermalloy 2268
(Thermalloy 2240 works equally well.)
I
col
= V
out
/R
load
or 3mA, whichever is greater.
(Include feedback R in R
load
.)
R
col
is a resistor (33Ω recommended) between the xxx collector and ±V
CC
.
T
j (pnp)
= P
pnp
(100 +
θ
ca
) + (P
cir
+ P
npn
)θ
ca
+ T
a
, similar for T
j (npn)
.
T
j (cir)
= P
cir
(17.5 +
θ
ca
) + (P
pnp
+ P
npn
)θ
ca
+ T
a
.
Figure 6: Transmission Line Matching
Non-inverting gain applications:
s
s
s
Connect R
g
directly to ground.
Make R
1
, R
2
, R
6
, and R
7
equal to Z
o
.
Use R
3
to isolate the amplifier from reactive
loading caused by the transmission line,
or by parasitics.
REV. 1A February 2001
5
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