TABLE 1. Composite Amplifier Measured Performance

AV

R1

Ω

R2

Ω

C2

pF

BW

MHz

SR

(V/µs)

en p-p

(mV

50

200

10k

8

3.3

178

37

100

100

10k

10

2.5

174

70

100

1k

100k

0.67

3.1

170

70

500

200

100k

1.75

1.4

96

250

1000

100

100k

2.2

0.98

64

400

In terms of the measured output peak-to-peak noise, the

following relationship holds between output noise voltage, e

n

p-p, for different closed-loop gain, A

Bandwidth is BW:

It should be kept in mind that in order to minimize the output

noise voltage for a given closed-loop gain setting, one could

minimize the overall bandwidth. As can be seen from Equa-

tion 1 above, the output noise has a square-root relationship

to the Bandwidth.

In the case of the inverting configuration, it is also possible to

increase the input impedance of the overall amplifier, by

raising the value of R1, without having to increase the feed-

back resistor, R2, to impractical values, by utilizing a "Tee"

network as feedback. See the LMC6442 data sheet (Appli-

cation Notes section) for more details on this.

20051519

FIGURE 5.

20051520

FIGURE 6.

20051521

FIGURE 7.

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