circuit shown in Figure 3. Figure 4 shows the frequency

response of the circuit. The test time for the 0.1Hz to

10Hz noise measurement should be limited to 10 sec-

onds, which has the effect of adding a second zero to

the test circuit, providing increased attenuation for fre-

quencies below 0.1Hz.

Current Noise Testing

The current-noise density can be calculated, once the

value of the input-referred noise is determined, by

using the standard expression given below:

where:

interest (V/

√Hz)

interest (A/

√Hz)

T = Ambient temperature in Kelvin (K)

source(s), if any.

terms in the numerator and denominator of the equation

given above should be eliminated because the Quan

i

e

AHz

n

no

VCL

n

p

n

p

VCL

2

2

) (4kT)(R +R )

(R +R )(A

)

=

[]

/

Single/Dual/Quad, 28MHz, Low-Noise,

Low-Voltage, Precision Op Amps

8

_______________________________________________________________________________________

Figure 3. 0.1Hz to 10Hz Voltage Noise Test Circuit

10

Ω

D.U.T

MAX410

0.1

μF

100k

Ω

2k

Ω

4.7

μF

100k

Ω

0.1

μF

24.9k

Ω

2k

Ω

4.7

μF

22

μF

TO SCOPE x1

Ω

110k

Ω

MAX410

MAX412

MAX414

Figure 4. 0.1Hz to 10Hz Voltage Noise Test Circuit, Frequency

Response

FREQUENCY (Hz)

10

1

0.1

20

40

60

80

100

0

0.01

100