LTC1051_1 Datasheet, PDF (10/16 Pages) Linear Technology – Dual/Quad Precision Zero-Drift Operational Amplifiers With Internal Capacitors

LTC1051/LTC1053
APPLICATIO S I FOR ATIO
5. For unity-gain inverting configuration, all the alias
frequencies are 80dB to 84dB down from the output signal
(Figures 6a, 6b). Combined with excellent THD under wide
swing, the LTC1051/LTC1053 op amps make efficient
unity gain inverters.
For gain higher than –1, the “signal to alias” ratio de-
creases at an approximate rate of –6dB per decade of
closed-loop gain (Figure 9).
6. For closed-loop gains of –10 or higher, the “signal to
alias” ratio degrades when the value of the feedback gain
setting resistor increases beyond 50k. For instance, the
68dB value of Figure 7 decreases to 56dB if a (1k, 100k)
resistor set is used to set the gain of –100.
7. When the LTC1051/LTC1053 are used as noninverting
amplifiers, all the previous approximate rules of thumb
apply with the following exceptions: when the closed-loop
gain is 10(V/V) and below, the “signal to alias” ratio is 1dB
to 3dB less than the inverting case; when the closed-loop
gain is 100(V/V), the degradation can be up to 9dB,
especially when the input signal is much higher than the
clock frequency (i.e. f_IN = 10kHz).
8. The signal/alias ratio performance improves when the
op amp has bandlimited loop gain.
SYSTEM BUSY, ONLY ABORT COMMANDS ALLOWED
RANGE: 11dBV
20dBV
STATUS: PAUSED
15dB
/DIV
68dB
R1
100Ω
90mV_P-P
10kHz
R2
10k
5V
–
1/2
LTC1051
+
0.1µF
V_OUT
50pF
–100
CENTER: 10 000Hz
X: 5475Hz
BW: 95.485Hz
Y: –58.05dBV
SPAN: 10 000Hz
– 5V
0.1µF
1051/53 F07
6f_CLK – f_IN
f_IN =10kHz
Figure 7. Output Voltage Spectrum of 1/2 LTC1051 Operating as an Inverting Amplifier with a Gain of –100 and
Amplifiying a 90mV_P-P, 10kHz Input Signal. With a 9V_P-P Output Swing the Measured 2nd Harmonic (20kHz)
was 75 Down from the 10kHz Input Signal
10
9
V_S = ±8V, T_A ≤85°C
8
7
6
V_S = ±5V, T_A ≤85°C
5
4
3
V_S = ±2.5V, T_A ≤85°C
2
1
NEGATIVE SWING
POSITIVE SWING
0
0 1k 2k 3k 4k 5k 6k 7k 8k 9k 10k
R_L (LOAD RESISTANCE,Ω)
1051/53 G08
Figure 8. Output Voltage Swing vs Load
10
90
V_S = ±5V
80
f_IN ≤10kHz
70
60
50
40
30
20
10
1
10
100
INVERTING CLOSED-LOOP GAIN
1051/53 G09
Figure 9. Signal to Alias Ratio vs
Closed-Loop Gain
10513fa