818 Series
1 kHz to 1.28 MHz
8-Bit Programmable
Description
The 818 Series are digitally programmable low-pass
and high-pass active filters that are tunable over a
256:1 frequency range. 818 filters are available with
any one of five standard factory-set tuning ranges or
8-bit custom ranges from 1 kHz to 1.28 MHz. These
units contain 8 CMOS logic inputs.
818 Series models are convenient, low profile, easy
to use fully finished filters which require no external
components or adjustments. They feature low
harmonic distortion, and near theoretical amplitude
characteristics. 818 filters operate from non-critical
±12 to ±18 Vdc power supplies, have a 5 kΩ (min.)
input impedance, a 10Ω (max.) output impedance
and low-pass models offer dc voltage offset
adjustment.
Features/Benefits:
• Low harmonic distortion and wide signal-to-noise
ratio to 12-bit resolution
• Digitally programmable corner frequency allows
selecting cut-off frequencies specific to each
application
• Plug-in ready-to-use, reducing engineering design
and manufacturing cycle time
• Factory-set tuning range, no external clocks or
adjustments needed
• Broad range of transfer characteristics and corner
frequencies to meet a wide range of applications
Applications
• Anti-alias and band-pass filtering
• Data acquisition systems
• Satellite and telecommunications
• Acoustic and vibration analysis and control
• Aerospace, navigation and sonar
• Medical research and electronic equipment
• Engine test and simulation
• Noise elimination
• Video systems
• Signal reconstruction
Available High-Pass Models:
. . . . . . . . . . . . . .
Page
818H8B 8-pole Butterworth . . . . . . . . . . . . . . . . . . 4
818H8E 8-pole, 6-zero elliptic, 1.77 . . . . . . . . . . . . 4
General Specifications:
Phase and phase match considerations . . . . . . . 5 & 6
Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . 7
Pin-out/package data. . . . . . . . . . . . . . . . . . . . . . . . . 7
Programmable Specifications.
. . . . . . . . . . . . .
Page
Digital Tuning & Control . . . . . . . . . . . . . . . . . . . . . . 2
Available Low-Pass Models:
. . . . . . . . . . . . . . .
Page
818L8B 8-pole Butterworth . . . . . . . . . . . . . . . . . . 3
818L8L
8-pole Bessel . . . . . . . . . . . . . . . . . . . . . . 3
818L8E 8-pole, 6-zero elliptic, 1.77 . . . . . . . . . . . . 3
818L8D80 8-pole, 6-zero constant delay . . . . . . . . . . 3
2" x 4"
8-Pole Filters
25 Locust St, Haverhill, Massachusetts 01830 • Tel: 800/252-7074, 978/374-0761 • FAX: 978/521-1839
e-mail: sales@freqdev.com • Web Address: http://www.freqdev.com
818 Series
8-Bit Programmable Filters
Digital Tuning Characteristics
The digital tuning interface circuits are two 4042 quad CMOS
latches which accept the following CMOS-compatible inputs:
eight tuning bits (D
0
- D
7
), a latch strobe bit (C), and a transition
polarity bit (P).
Filter tuning follows the tuning equation given below:
f
c
= ( f
max
/256 ) [ 1 + D
7
x 2 + D
6
x 2 + D
5
x 2 + D
4
x 2 + D
3
x
2 + D
2
x 2 + D
1
x 2 + D
0
x 2 ]
where D
1
- D
7
= "0" or "1", and
f
max
= Maximum tuning frequency;
f
c
= corner frequency;
Minimum tunable frequency = f
max
/256 (D
0
thru D
7
= 0);
Minimum frequency step (Resolution) = f
max
/256
3
2
1
0
7
6
5
4
Digital Tuning &
Control Characteristics
Pin-Out Key
IN
OUT
GND
"P"
"C"
+Vs
-Vs
Os
NC
Analog Input Signal
Analog Output Signal
Power and Signal Return
Transition Polarity Bit
Tuning Strobe Bit
Supply Voltage, Positive
Supply Voltage, Negative
Optional Offset Adjustment
No Connect (Highpass Models)
D
7
Tuning
D
6
Tuning
D
5
Tuning
D
4
Tuning
D
3
Tuning
D
2
Tuning
D
1
Tuning
D
0
Tuning
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
7 (MSB)
6
5
4
3
2
1
0 (LSB)
OUT +Vs -Vs
D
7
D
6
D
5
D
4
GND
D
3
D
2
D
1
D
0
IN Os/NC
Data Control Specifications
Data Control Lines
Functions
Data Control Modes
Mode 1
Mode 2
Input Data Levels
Latch Strobe (C)
Transition Polarity (P)
Bottom View
P C
P = 0; C = 0
frequency follows input codes
P = 0; C = 0⇑
frequency latched on rising edge
P = 1; C = 1
frequency follows input codes
P = 1; C = 1⇓
frequency latched on falling edge
(CMOS Logic)
4 Vdc max.
15 Vdc max.
-1 mA max.
+1
µA
max.
7.5 pF max.
MSB
2
7
D
7
0
0
- 10
µA
typ.
-5
+10
µA
typ.
5 pF typ
25 nS
50 nS
80 nS min.
Frequency Select Bits
Logic "1" = +Vs
Logic "0" = Gnd
(Binary-Coded)
LSB (least significant bit)
MSB (most significant bit)
256 : 1, Binary Weighted
-5
---
2
6
D
6
0
0
0
0
0
0
0
1
1
---
2
5
D
5
0
0
0
0
0
0
1
1
1
---
2
4
D
4
0
0
0
0
0
1
1
1
1
---
2
3
D
3
0
0
0
0
1
1
1
1
1
---
2
2
D
2
0
0
0
1
1
1
1
1
1
---
2
1
D
1
0
0
1
1
1
1
1
1
1
LSB
2
0
D
0
0
1
1
1
1
1
1
1
1
Bit
Weight
fc
Corner
Frequency
Input Voltage (Vs = 15 Vdc)
Low Level In
0 Vdc min.
High Level In
11 Vdc min.
Input Current
High Level In
Low Level In
Input Capacitance
Latch Response
1
Data Set Up Time
2
Data Hold Time
Strobe Pulse Width
Input Data Format
Positive Logic
Bit Weighting
D
0
D
7
Frequency Range
f
max
/256
f
max
/128
f
max
/64
f
max
/32
f
max
/16
f
max
/8
f
max
/4
f
max
/2
fmax
0
0
0
0
0
0
1
Notes:
1.Frequency data must be present before occurrence of strobe edge.
2.Frequency data must be present after occurrence of strobe edge.
2
25 Locust St, Haverhill, Massachusetts 01830 • Tel: 800/252-7074, 978/374-0761 • FAX: 978/521-1839
e-mail: sales@freqdev.com • Web Address: http://www.freqdev.com
818 Series
8-Bit Programmable
Model
Product Specifications
Transfer Function
Size
Range f
c
Theoretical Transfer
Characteristics
Passband Ripple
(theoretical)
8-Pole
Low-Pass Filters
818L8L
818L8E
818L8D80
818L8B
8-Pole,
Butterworth
2.0” x 4.0” x 0.4”
1 kHz to 128 MHz
Appendix A
Page 9
0.0 dB
0 ± 0.1 dB max.
0 ± 0.05 dB typ.
48 dB/octave
f
c
± 0.01% /°C
- 3 dB
-360°
0.12 dB
3.01 dB
60.0 dB
80.0 dB
See page 5 & 6
± 0.5 dB max.
± 0.25 dB typ.
0.6 f
c
- 1.0 f
c
± 1.0 dB max.
± 0.6 dB typ.
< - 88 dB typ.
300
µVrms
typ.
75
µVrms
typ.
0 - 0.6 f
c
± 3% max.
8-Pole,
Bessel
2.0” x 4.0” x 0.4”
1 kHz to 1.28 MHz
Appendix A
Page 4
0.0 dB
0 ± 0.1 dB max.
0 ± 0.05 dB typ.
48 dB/octave
f
c
± 0.01% /°C
- 3 dB
-182°
1.91 dB
3.01 dB
60.0 dB
80.0 dB
See page 5 & 6
0 - f
c
± 0.8 dB max.
± 0.4 dB typ.
± 3% max.
8-Pole, 6 zero,
Elliptic
2.0” x 4.0” x 0.4”
1 kHz to 1.28 MHz
Appendix A
Page 24
± 0.035 dB
0 ± 0.1 dB max.
0 ± 0.05 dB typ.
80 dB min.
f
r
± 0.01% /°C
- 0.035 dB
- 323.5°
0.035 dB
3.01 dB
60.0 dB
80.0 dB
See page 5 & 6
± 0.5 dB max.
± 0.25 dB typ.
0.8 f
c
- 1.0 f
r
± 1.0 dB max.
± 0.5 dB typ.
< - 88 dB typ.
350
µVrms
typ.
75
µVrms
typ.
0 - 0.8 f
r
± 3% max.
8-Pole, 6 zero,
Constant Delay
2.0” x 4.0” x 0.4”
1 kHz to 1.28 MHz
Appendix A
Page 21
0.15 dB
0 ± 0.1 dB max.
0 ± 0.05 dB typ.
80 dB min.
f
c
± 0.01% /°C
- 3 dB
-306°
3.01 dB
60.0 dB
80.0 dB
See page 5 & 6
0 - 0.8 f
c
0.8 f
c
- 1.0 f
c
± 0.5 dB max.
± 0.25 dB typ.
± 1.0 dB max.
± 0.5 dB typ.
± 3% max.
DC Voltage Gain
(non-inverting)
Stopband
Attenuation Rate
Cutoff Frequency
Stability
Amplitude
Phase
Filter Attenuation
(theoretical)
0.80 f
c
1.00 f
c
2.37 f
c
3.16 f
c
0.80 f
c
1.00 f
c
4.52 f
c
6.07 f
c
1.00 f
r
1.13 f
r
1.67 f
r
1.77 f
r
1.00 f
c
3.08 f
c
3.57 f
c
Phase Match
1
Amplitude Accuracy
(theoretical)
Total Harmonic
Distortion @ 1 kHz
Wide Band Noise
(5 Hz - 2 MHz)
< - 88 dB typ.
300
µVrms
typ.
75
µVrms
typ.
< - 88 dB typ.
300
µVrms
typ.
75
µVrms
typ.
Narrow Band Noise
(5 Hz - 100 kHz)
Filter Mounting
Assembly
FMA-04A
FMA-04A
FMA-04A
FMA-04A
1.Unit to unit match for the same transfer function, set to the same frequency and operating configuration, and from the same manufacturing lot.
3
25 Locust St, Haverhill, Massachusetts 01830 • Tel: 800/252-7074, 978/374-0761 • FAX: 978/521-1839
e-mail: sales@freqdev.com • Web Address: http://www.freqdev.com
818 Series
8-Bit Programmable
Model
Product Specifications
Transfer Function
Size
Range f
c
Theoretical Transfer
Characteristics
Passband Ripple
(theoretical)
8-Pole
High-Pass Filters
818H8E
818H8B
8-Pole,
Butterworth
2.0” x 4.0” x 0.4”
1 kHz to 1.28 MHz
Appendix A
Page 29
0.0 dB
0 ± 0.5 dB to 1.28 MHz
(-6 dB) 5 MHz
48 dB/octave
f
c
± 0.01% /°C
- 3 dB
-360°
80 dB
60 dB
3.01 dB
0.00 dB
± 3% max.
8-Pole, 6-zero,
Elliptic
2.0” x 4.0” x 0.4”
1 kHz to 1.28 MHz
Appendix A
Page 37
± 0.035 dB
0 ± 0.5 dB to 1.28 MHz
(-6 dB) 5 MHz
80 dB
f
r
± 0.01% /°C
- 0.035 dB
-323.5°
80.0 dB
60.0 dB
3.01 dB
0.03 dB
00.0 dB
± 3% max.
Voltage Gain
(non-inverting)
Power Bandwidth
Stopband
Attenuation Rate
Cutoff Frequency
Stability
Amplitude
Phase
Filter Attenuation
(theoretical)
0.31 f
c
0.42 f
c
1.00 f
c
2.00 f
c
0.56 f
r
0.60 f
r
0.88 f
r
1.00 f
r
2.00 f
r
Amplitude Accuracy
(theoretical)
1.0 - 1.25 f
c
± 0.5 dB max.
± 0.3 dB typ.
1.25f
c
-1.28MHz± 1.0 dB max.
± 0.5 dB typ.
< - 88 dB typ.
400
µVrms
typ.
100
µVrms
typ.
FMA-04A
1.00 - 1.25 f
r
± 0.5 dB max.
± 0.3 dB typ.
1.25f
r
-1.28MHz± 1.0 dB max.
± 0.5 dB typ.
< - 88 dB typ.
450
µVrms
typ.
100
µVrms
typ.
FMA-04A
Total Harmonic
Distortion @ 1 kHz
Wide Band Noise
Narrow Band Noise
Filter Mounting
Assembly
1.Unit to unit match for the same transfer function, set to the same frequency and operating configuration, and from the same manufacturing lot.
4
25 Locust St, Haverhill, Massachusetts 01830 • Tel: 800/252-7074, 978/374-0761 • FAX: 978/521-1839
e-mail: sales@freqdev.com • Web Address: http://www.freqdev.com
818 Series
1 kHz to 1.28 MHz
Phase Deviation from Theoretical:
The phase response of the amplifiers and the
capacitance of the frequency control switches of the 818
series contribute to the overall phase response and
cause it to deviate from theoretical. For the higher
frequency models ( -4 and -5 ), where the cutoff
frequencies can be programmed up to 1.28MHz, the
deviation from theoretical can be substantial.
Figure 1 is a normalized plot of the phase deviation from
theoretical for an 818L8E-5 for programmed cutoff
frequencies from 5kHz ( fc min ) to 1.28MHz (fc max ).
For fc of 5kHz, the deviation from the 323° theoretical
phase shift is 2° but for fc of 1.28MHz the deviation is
78°. This set of curves can be used to estimate the
deviation from theoretical phase for other models in the
818 series.
Figure 1 represents a "maximum deviation from
theoretical phase" situation. Other models (i.e. -1 to -4)
will exhibit a similar set of phase deviation curves with
the phase scale being reduced by the ratio of the f max
of the model to the f max of the -5. For example, an L8E-
1, whose programming frequency range is from 1kHz to
256kHz (1/5 of the range of the -5 model) will have a
similar set of phase deviation curves but the maximum
phase deviation, at the highest frequency setting (fc
max), will be approximately 1/5 that of the -5 model (78/5
= 15.6°). The other programmed settings of the -1 will
also produce proportionally reduced phase deviations.
Unit to Unit Phase Match
2
The actual phase shift through a filter at a frequency " f "
is determined by its programmed frequency " fc ", the
theoretical phase response of the transfer function (B, L,
E, or D80) and the phase deviation from theoretical
which in turn depends upon component tolerances, the
model # (i.e. -1 through -5) and frequency to which it is
programmed. It is therefore not possible to have a
meaningful unit to unit phase match that is specified by a
single number.
For a group of the same model type and number,
programmed to the same frequency, the unit to unit
phase match can be approximated as a percentage of
the theoretical phase shift with a correction term added
to accommodate amplifier induced phase deviations.
Phase and Phases
Match Considerations
EXAMPLE: Phase Match Calculation
∆Φ(f)max
= 0.02° x
Φτ(f)
+ 4.0° x f/fc x fmax/1.28MHz
4.0° - L8L
3.0° - L8B & L8D80
2.0° - L8L
∆Φ(f)typ
=0.5 x
∆Φ(f)max
where:
∆Φ(f)
Φτ
(f)
f
f max
fc
=
=
=
=
=
phase match at frequency f
theoretical phase shift at f
frequency of interest
maximum fc of the model
frequency to which the filter is
programmed
Eg. - for an 818L8E-3, the phase deviation from
theoretical at a frequency of 192kHz, when the cutoff
frequency fc is programmed to 384kHz is:
f/fc = 192kHz/384kHz = 0.5, fmax = 768kHz
Φτ(f)
= 133° (from data table at f/fc = 0.5)
Phase Match:
∆Φ(f)max
= 0.02° x
Φτ(f)
+ 4.0° x f/fc x fmax/1.28MHz
= 0.02 x (-133°) + 4.0° x 0.5 x 768kHz/1.28MHz
= 2.66° + 1.20° = +3.86°
∆Φ(f)typ
=0.5 x
∆Φ(f)max
= 0.5° x 3.86° = 1.93°
818L8E Phase Deviation (in degrees “°”) from
Theoretical vs. Normalized Input Frequency
programmed setting of fc
f/fc
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.85
0.90
0.95
1.00
5kHz
0.15
0.30
0.34
0.20
0.20
0.00
-0.21
-0.50
-0.80
-1.20
-1.90
-2.50
10kHz
0.18
0.32
0.42
0.40
0.32
0.00
-0.30
-0.60
-1.00
-1.60
-2.40
-3.30
20kHz
0.17
0.30
0.40
0.50
0.60
-0.10
-0.60
-1.30
-1.80
-2.50
-3.50
-4.60
40kHz
0.08
0.17
-0.18
-0.20
-0.40
-0.80
-1.30
-2.10
-2.80
-3.70
-4.80
-6.20
80kHz
-0.12
-0.39
-0.57
-0.90
-1.20
-1.90
-2.70
-3.80
-4.70
-5.80
-7.30
-8.90
160kHz
-0.52
-1.03
-1.59
-2.30
-3.00
-4.10
-5.40
-7.20
-8.40
-10.00
-12.00
-14.10
320kHz
-1.18
-2.41
-3.66
-5.10
-6.70
-8.70
-11.00
-13.90
-15.80
-18.40
-21.10
-24.30
640kHz 1.28MHz
-2.57 -5.32
-5.17 -10.76
-7.89 -16.29
-10.80 -22.10
-14.00 -28.20
-17.70 -35.10
-21.80 -42.60
-26.90 -51.30
-30.10 -56.40
-33.80 -62.30
-38.30 -69.20
-43.30 -77.50
5
25 Locust St, Haverhill, Massachusetts 01830 • Tel: 800/252-7074, 978/374-0761 • FAX: 978/521-1839
e-mail: sales@freqdev.com • Web Address: http://www.freqdev.com
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