LTC1066-1
18
10661fa
–
+
–
+
–
+
–
+
13121110
R
F
–
+
–
+
+
V
IN
C
P
50pF
C
A
0.047µF
0.1µF
7
9
5
12
5
7
8
10
9
15
16
2
6
11
14
3
1
4
3
2
8
15
16
17
18
413
19
LTC1045
14
R
A
PULSE
OUTPUT
6
R
P
2k
12.1k
1k
500Ω
500Ω
0.1µF
0.1µF
CLOCK INPUT
(TTL OR CMOS)
PULSE
AVERAGE
CLOCK FREQUENCY DETECTOR
20
LTC1045
1
1µF
5V
0.1µF
0.1µF
0.1µF
LTC202
–5V 5V
5V
C3
C2
R1
1k
R
IN
*
200Ω
20Ω
20Ω
CLOCK-TUNABLE,
8TH ORDER LOWPASS FILTER
FIRST ORDER RC
LOWPASS ANTI-ALIASING FILTER
1
C
F
18
0.1µF
C1
C
IN
*
0.1µF
0.1µF
0.1µF
V
OUT
0.1µF0.1µF
–5V
C4
C5
217
316
415
514
613
712
811
910
V
+
OUT B
+IN B
GND
LTC1066-1
F
IN
COMP 2
CON 2
COMP 1
V
–
OUT A
–IN A
+IN A
V
–
V
+
CON 1
F OUT
50/100
CLK
COMPONENT CALCULATIONS FOR A CLOCK-TUNABLE RANGE OF FIVE OCTAVES:
DEFINITIONS: 1. THE CUTOFF FREQUENCY OF LTC1066-1 IS ABBREVIATED AS f
C
2. f
C(LOW)
IS THE LOWEST CUTOFF FREQUENCY OF INTEREST
3. A RANGE OF FIVE OCTAVES IS FROM f
C(LOW)
TO 32f
C(LOW)
COMPONENT CALCULATIONS:
EXAMPLE:
1
2πR
F
C
F
f
C(LOW)
125
1
f
C(LOW)
= ; R
IN
* = R
F
(IF R
F
CAN BE CHOSEN TO BE 20k, R
IN
AND C
IN
ARE OMITTED.
f
C(LOW)
/125 ALLOWS FOR 0.2dB GAIN PEAK IN THE PASSBAND)
C1 = µF (f
C(LOW)
IN Hz) ; R1 = 1k
10
5
50•f
C(LOW)
5 × 10
5
50•f
C(LOW)
C
P
= 50pF; R
P
= k
C
A
= 0.047µF; R
A
= k
C2 = C1, C3 = 2•C1, C4 = 4•C1, C5 = 8•C1
LET’S CHOOSE A FIVE OCTAVE RANGE FROM 1kHz TO 32kHz. f
C(LOW)
= 1kHz (1000Hz).
LET C
F
= 1µF, THEN R
F
CALCULATES TO BE 20k. R
IN
AND C
IN
OMITTED;
R1 = 1k, C1 = 0.001µF, C2 = 0.001µF, C3 = 0.0022µF, C4 = 0.0039µF,
C5 = 0.0082µF. C
P
= 50pF, R
P
= 2k, C
A
= 0.047µF, R
A
= 10k
1066-1 TA07
DC Accurate Clock-Tunable Lowpass Filter with Tunable Input Anti-Aliasing Filter
(Circuit provides at least – 20dB attenuation to input frequencies at 2f
CLK
.
The clock-tunable range is 5 octaves.)
TYPICAL APPLICATIO
U
