CA5160 查看數據表（PDF） - Intersil
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CA5160 Datasheet PDF : 18 Pages
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CA5160
V+
7
3
+
2
-
Q8
OUTPUT
STAGE
Q12
6
RL
4
8
V-
FIGURE 4A. DUAL POWER-SUPPLY OPERATION
V+
7
3
+
2
-
Q8 OUTPUT
STAGE
Q12
6
RL
4
8
FIGURE 4B. SINGLE POWER-SUPPLY OPERATION
FIGURE 4. CA5160 OUTPUT STAGE IN DUAL AND SINGLE
POWER SUPPLY OPERATION
Wideband Noise
From the standpoint of low-noise performance consider-
ations, the use of the CA5160 is most advantageous in appli-
cations where in the source resistance of the input signal is
on the order of 1MΩ or more. In this case, the total input-
referred noise voltage is typically only 40µV when the test-
circuit amplifier of Figure 5 is operated at a total supply volt-
age of 15V. This value of total input-referred noise remains
essentially constant, even though the value of source resis-
tance is raised by an order of magnitude. This characteristic
is due to the fact that reactance of the input capacitance
becomes a significant factor in shunting the source resis-
tance. It should be noted, however, that for values of source
resistance very much greater than 1MΩ, the total noise volt-
age generated can be dominated by the thermal noise con-
tributions of both the feedback and source resistors.
+7.5V
RS
1MΩ
3
+
2-
0.01µF
7
6
4
NOISE
VOLTAGE
OUTPUT
30.1kΩ
0.01
µF
-7.5V
BW (-3dB) = 200kHz
TOTAL NOISE VOLTAGE
1kΩ
(INPUT REFERRED) = 40µV (TYP)
FIGURE 5. TEST-CIRCUIT AMPLIFIER (30dB GAIN) USED FOR
WIDEBAND NOISE MEASUREMENTS
Typical Applications
Voltage Followers
Operational amplifiers with very high input resistances, like
the CA5160, are particularly suited to service as voltage
followers. Figure 6 shows the circuit of a classical voltage
follower, together with pertinent waveforms using the
CA5160 in a split supply-configuration.
A voltage follower, operated from a single-supply, is shown in
Figure 7 together with related waveforms. This follower circuit
is linear over a wide dynamic range, as illustrated by the
reproduction of the output waveform in Figure 7B with input
signal ramping. The waveforms in Figure 7C show that the
follower does not lose its input-to-output phase-sense, even
though the input is being swung 7.5V below ground potential.
This unique characteristic is an important attribute in both
operational amplifier and comparator applications. Figure 7C
also shows the manner in which the CMOS output stage
permits the output signal to swing down to the negative supply
rail potential (i.e., ground in the case shown). The digital-to-
analog converter (DAC) circuit, described in the following
section, illustrates the practical use of the CA5160 in a single-
supply voltage follower application.
+7.5V
3
+
10kΩ
0.01µF
7
6
2
BW (-3dB) = 4MHz
SR = 10V/µs
-
4
0.01
µF
-7.5V
2kΩ
0.1µF
2kΩ
25pF
SIMULATED
LOAD
CAPACITANCE
FIGURE 6A. DUAL SUPPLY FOLLOWER
3-8
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