SM73302_15 Datasheet, PDF (21/31 Pages) Texas Instruments – SM73302 88 MHz, Precision, Low Noise, 1.8V CMOS Input, Decompensated Operational Amplifier

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SM73302
SNOSB93A – AUGUST 2011 – REVISED APRIL 2013
Figure 57. R_C = 330Ω and C = 10 nF, Gain = +1
Figure 58. LMP7715 Response Gain = +1
With no increase in power consumption the decompensated op amp offers faster speed than the compensated
equivalent part . These examples used R_F = 2 kΩ. This value is high enough to be easily driven by the SM73302,
yet small enough to minimize the effects from the parasitic capacitance of both the PCB and the op amp.
Note: When using the SM73302, proper high frequency PCB layout must be followed. The GBW of these parts is
88 MHz, making the PCB layout significantly more critical than when using the compensated counterparts which
have a GBW of 17 MHz.
TRANSIMPEDANCE AMPLIFIER
An excellent application for the SM73302 is as a transimpedance amplifier. With a GBW product of 88 MHz this
part is ideal for high speed data transmission by light. The circuit shown on the front page of the datasheet is the
circuit used to test the SM73302 as a transimpedance amplifier. The only change is that V_B is tied to the V_CC of
the part, thus the direction of the diode is reversed from the circuit shown on the front page.
Very high speed components were used in testing to check the limits of the SM73302 in a transimpedance
configuration. The photodiode part number is PIN-HR040 from OSI Optoelectronics. The diode capacitance for
this part is only about 7 pF for the 2.5V bias used (V_CC to virtual ground). The rise time for this diode is 1 nsec. A
laser diode was used for the light source. Laser diodes have on and off times under 5 nsec. The speed of the
selected optical components allowed an accurate evaluation of the SM73302 as a transimpedance amplifier. An
evaluation board for decompensated op amps, PN 551013271-001 A, was used and only minor modifications
were necessary and no traces had to be cut.
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