Simplified Schematic

Applications Tips

The LM6361 has been compensated for unity-gain opera-

tion. Since this compensation involved adding emitter-

degeneration resistors to the op amp’s input stage, the

open-loop gain was reduced as the stability increased. Gain

error due to reduced A

thus, for gains between 5 and 25, the less-compensated

LM6364 should be used, and the uncompensated LM6365 is

appropriate for gains of 25 or more. The LM6361, LM6364,

and LM6365 have the same high slew rate, regardless of

their compensation.

The LM6361 is unusually tolerant of capacitive loads. Most

op amps tend to oscillate when their load capacitance is

greater than about 200 pF (especially in low-gain circuits).

The LM6361’s compensation is effectively increased with

load capacitance, reducing its bandwidth and increasing its

stability.

Power supply bypassing is not as critical for the LM6361 as

it is for other op amps in its speed class. Bypassing will, how-

ever, improve the stability and transient response and is rec-

ommended for every design. 0.01 µF to 0.1 µF ceramic ca-

pacitors should be used (from each supply “rail” to ground);

if the device is far away from its power supply source, an ad-

ditional 2.2 µF to 10 µF of tantalum may provide extra noise

reduction.

Keep all leads short to reduce stray capacitance and lead in-

ductance, and make sure ground paths are low-impedance,

especially where heavier currents will be flowing. Stray ca-

pacitance in the circuit layout can cause signal coupling

across adjacent nodes and can cause gain to unintentionally

vary with frequency.

Breadboarded circuits will work best if they are built using

generic PC boards with a good ground plane. If the op amps

are used with sockets, as opposed to being soldered into the

circuit, the additional input capacitance may degrade circuit

performance.

Typical Applications

DS009057-3

Offset Voltage Adjustment

DS009057-4

1 MHz Low-Pass Filter

DS009057-10

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