LMH6601QMG/NOPB National Semiconductor, LMH6601QMG/NOPB Datasheet - Page 24

• Manufacturer Part Number: LMH6601QMG/NOPB
• Description: IC AMP VFA 2.4V SHUTDOWN SC70-6
• Manufacturer: National Semiconductor

Specifications of LMH6601QMG/NOPB

• Amplifier Type: Voltage Feedback
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• Slew Rate: 275 V/µs
• Gain Bandwidth Product: 155MHz
• -3db Bandwidth: 250MHz
• Current - Input Bias: 5pA
• Voltage - Input Offset: 1000µV
• Current - Supply: 9.6mA
• Current - Output / Channel: 180mA
• Voltage - Supply, Single/dual (±): 2.4 V ~ 5.5 V, ±1.2 V ~ 2.75 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SC-70-6, SC-88, SOT-363
• Number Of Channels: 1
• Voltage Gain Db: 66 dB
• Common Mode Rejection Ratio (min): 56 dB
• Input Offset Voltage: 2.4 mV at 5 V
• Operating Supply Voltage: 3 V, 5 V
• Supply Current: 11.5 mA at 5 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LMH6601QMG; LMH6601QMG; LMH6601QMGTR

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The diode capacitance (C
of the LMH6601 (C
cuit and how it is compensated. With large transimpedance
gain values (R
plifier inverting input (C
create a zero in the Noise Gain (NG) function (see
14). If left untreated, at higher frequencies where NG equals
the open loop transfer function there will be excess phase shift
around the loop (approaching 180°) and therefore, the circuit
could be unstable. This is illustrated in
FIGURE 14. Transimpedance Amplifier Graphical
(pF)
500
C
10
50
D
Stability Analysis and Compensation
F
), the total combined capacitance on the am-
TABLE 3. Transimpedance Amplifier
(pF)
502
C
12
52
A
IN
) has a bearing on the stability of this cir-
GBWP = 155 MHz
IN
C
D
= C
V
) along with the input capacitance
A
S
= 2 pF
C
= 5V
D
F
+ C
_Calculated
(pF)
A
1.1
2.3
7.2
) will work against R
Figure
14.
C
Figure
20136460
F
(pF)
used
F
1
3
8
Figure 12
to
24
Compensation and Performance Results
Figure 14
value, across R
For optimum performance, this capacitor is usually picked so
that NG is equal to the op amp's open loop gain at f
cause a “flattening” of the NG slope beyond the point of in-
tercept of the two plots (open loop gain and NG) and will
results in a Phase Margin (PM) of 45° assuming f
at least a decade apart. This is because at the point of inter-
cept, the NG pole at f
which leaves 45° of PM. For reference,
the transimpedance gain (I-V (Ω))
Here is the theoretical expression for the optimum C
and the expected −3 dB bandwidth:
Table
and conditions, of testing the LMH6601 with various photodi-
odes having different capacitances (C
gain (R
Calculated (MHz)
−3 dB BW
3, below, lists the results, along with the assumptions
F
) of 10 kΩ.
14
7
2
shows that placing a capacitor, C
F
will create a pole in the NG function at f
P
Measured (MHz)
will have a 45° phase lead contribution
−3 dB BW
7.0
2.5
15
D
) at a transimpedance
Figure 14
Step Response
Overshoot (%)
F
, with the proper
P
also shows
6
4
9
P
and f
. This will
F
value
Z
(10)
are
(9)
P
.