LTC1051 查看數據表（PDF） - Linear Technology

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LTC1051

Dual/Quad Precision Zero-Drift Operational Amplifiers With Internal Capacitors

Linear Technology 

LTC1051/LTC1053

APPLICATIO S I FOR ATIO

2. If we arbitrarily accept that “aliasing” occurs when

output alias signals reach an amplitude of 0.01% or more

of the output signal, then: the approximate minimum

frequency of an AC input signal which will cause aliasing

is equal to the internal clock frequency multiplied by the

square root of the op amp feedback factor. For instance,

with closed-loop gain of –10, the feedback factor is 1/11

and if fCLK = 2.6kHz, alias signals can be detected when

the frequency of the input signal exceeds 750Hz to 800Hz

(Figure 5a).

3. The number of alias signals increases when the input

signal frequency increases (Figure 5b).

4. When the frequency, fIN, of the input signal is less than

fCLOCK, the alias signal(s) amplitude(s) directly scale with

the amplitude of the incoming signal. The output “signal to

alias ratio” cannot be increased by just boosting the input

signal amplitude. However, when the input AC signal

frequency well exceeds the clock frequency, the amplitude

of the alias signals does not directly scale with the input

amplitude. The “signal to alias ratio” increases when the

output swings closely to the rails. (See Figure 5b and

Figure 7.) It is important to note that the LTC1051/

LTC1053 op amps, under light loads (RL ≥ 10k), swing

closely to the supply rails without generating harmonic

distortion (Figure 8).

B: MAG

RANGE: 9dBV

13dBV

STATUS: PAUSED

RMS: 25

10k

15dB

/DIV

83.5dB

5V

0.1µF

10k

–

1/2

LTC1051

+

50pF

–107

CENTER: 2 625Hz

X: 2535Hz

BW: 19.097Hz

Y: – 74.16dBV

NOTE: THE fCLK – fIN = 85Hz

ALIAS FREQUENCY IS 95dB

DOWN FROM THE OUTPUT LEVEL

2fCLK – fIN

fCLK fIN = 2.685kHz

SPAN: 2 000Hz

VIN = 10kHz

8VP-P

0.1µF

– 5V

Figure 6a. Output Voltage Spectrum of 1/2 LTC1051 Operating as a Unity-Gain Inverting Amplifier.

VS = ±5V, RL = 10k, CL = 50pF, VIN = 8VP-P, 2.685kHz

B: MAG

RANGE: 9dBV

13dBV

STATUS: PAUSED

RMS: 50

1051/53 F05a

15dB

15dB

/DIV

80dB

–107

CENTER: 10 000Hz

X: 10000Hz

BW: 95.485Hz

Y: 7.98dBV

5fCLK – fIN

fIN – 2fCLK

2 • fCLK

6fCLK – fIN

fIN – fCLK

NOTE: ALL ALIAS FREQUENCY

80dB TO 84dB DOWN FROM OUTPUT

fIN = 10kHz

SPAN: 10 000Hz

1kHz

Figure 6b. Output Voltage Spectrum of 1/2 LTC1051 Operating as a Unity-Gain Inverting Amplifier.

VS = ±5V, RL = 10k, CL = 50pF, VIN = 8VP-P, 10kHz

10513fa

9

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