CLC1002ISO8X 查看數據表（PDF） - Exar Corporation

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CLC1002ISO8X

Ultra-Low Noise Amplifer

Exar Corporation 

Data Sheet

in figure 3 would be calculated as:

+ eR2s

2

2

1 + Rf

Rg

+

eR2g

Rf

Rg

+ eR2f

RL || (Rf + Rg)

external resistor noiseTtheermses mfoeraRssu,reRmg eanntds Rarfe basic and are relatively easy to

perform with standard lab equipment. For design purposes

external resistor noise terms for RS, Rg and Rf

however, prior knowledge of actual signal levels and load

impedance is needed to determine the dissipated power.

High source impedances are sometimes unavoidable, but

they increase noise from the source impedance and also

Here, PD can be found from

PD = PQuiescent + PDynamic - PLoad

make the circuit more sensitive to the op amp current

noise. Analyze all noise sources in the circuit, not just the

op amp itself, to achieve low noise in your application.

Quiescent power can be derived from the specified IS

values along with known supply voltage, VSupply. Load

power can be calculated as above with the desired signal

amplitudes using:

Power Dissipation

Power dissipation should not be a factor when operating

under the stated 500Ω load condition. However,

applications with low impedance, DC coupled loads

should be analyzed to ensure that maximum allowed

junction temperature is not exceeded. Guidelines listed

below can be used to verify that the particular application

will not cause the device to operate beyond it’s intended

operating range.

Maximum power levels are set by the absolute maximum

junction rating of 150°C. To calculate the junction

temperature, the package thermal resistance value

ThetaJA (ӨJA) is used along with the total die power

dissipation.

TJunction = TAmbient + (ӨJA × PD)

Where TAmbient is the temperature of the working environment.

In order to determine PD, the power dissipated in the load

needs to be subtracted from the total power delivered by

the supplies.

PD = Psupply - Pload

Supply power is calculated by the standard power

equation.

(VLOAD)RMS = VPEAK / √2

( ILOAD)RMS = ( VLOAD)RMS / Rloadeff

The dynamic power is focused primarily within the output

stage driving the load. This value can be calculated as:

PDYNAMIC = (VS+ - VLOAD)RMS × ( ILOAD)RMS

Assuming the load is referenced in the middle of the

power rails or Vsupply/2.

Figure 4 shows the maximum safe power dissipation in the

package vs. the ambient temperature for the packages

available.

2.5

2

SOIC-8

1.5

SOT23-6

1

0.5

0

-40 -20

0

20

40

60

80

Ambient Temperature (°C)

100 120

Figure 4. Maximum Power Derating

Psupply = Vsupply × IRMS supply

Vsupply = VS+ - VS-

Power delivered to a purely resistive load is:

Pload = ((VLOAD)RMS2)/Rloadeff

The effective load resistor (Rloadeff) will need to include

the effect of the feedback network. For instance, Rloadeff

©2007-2013 Exar Corporation

Driving Capacitive Loads

Increased phase delay at the output due to capacitive loading

can cause ringing, peaking in the frequency response, and

possible unstable behavior. Use a series resistance, RS,

between the amplifier and the load to help improve stability

and settling performance. Refer to Figure 5.

14/17

Rev 1G

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