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
1 kHz to 1.28 MHz
8-Bit Programmable
818 Series
2" x 4"
8-Pole Filters
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 k
(min.)
input impedance, a 10
(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
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
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
8-Bit Programmable Filters
818 Series
Digital Tuning &
Control Characteristics
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
2
MSB
---
---
---
---
---
---
LSB
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
0
0
0
0
0
0
0
0
f
max
/256
0
0
0
0
0
0
0
1
f
max
/128
0
0
0
0
0
0
1
1
f
max
/64
0
0
0
0
0
1
1
1
f
max
/32
0
0
0
0
1
1
1
1
f
max
/16
0
0
0
1
1
1
1
1
f
max
/8
0
0
1
1
1
1
1
1
f
max
/4
0
1
1
1
1
1
1
1
f
max
/2
1
1
1
1
1
1
1
1
fmax
Bit
Weight
fc
Corner
Frequency
+Vs
OUT
-Vs
D
D
D
D
GND
D
D
D
D
C
P
IN
Bottom View
Os/NC
4
5
3
2
1
0
6
7
Pin-Out Key
IN
Analog Input Signal
D
7
Tuning Bit 7 (MSB)
OUT Analog Output Signal
D
6
Tuning Bit 6
GND Power and Signal Return
D
5
Tuning Bit 5
"P"
Transition Polarity Bit
D
4
Tuning Bit 4
"C"
Tuning Strobe Bit
D
3
Tuning Bit 3
+Vs
Supply Voltage, Positive
D
2
Tuning Bit 2
-Vs
Supply Voltage, Negative
D
1
Tuning Bit 1
Os
Optional Offset Adjustment
D
0
Tuning Bit 0 (LSB)
NC
No Connect (Highpass Models)
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
7
+ D
6
x 2
6
+ D
5
x 2
5
+ D
4
x 2
4
+ D
3
x
2
3
+ D
2
x 2
2
+ D
1
x 2
1
+ D
0
x 2
0
]
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
Data Control Specifications
Data Control Lines
Functions
Latch Strobe (C)
Transition Polarity (P)
Data Control Modes
Mode 1
P = 0; C = 0
frequency follows input codes
P = 0; C = 0
frequency latched on rising edge
Mode 2
P = 1; C = 1
frequency follows input codes
P = 1; C = 1
frequency latched on falling edge
Input Data Levels
(CMOS Logic)
Input Voltage (Vs = 15 Vdc)
Low Level In
0 Vdc min.
4 Vdc max.
High Level In
11 Vdc min.
15 Vdc max.
Input Current
High Level In
- 10
-5
A typ.
-1 mA max.
Low Level In
+10
-5
A typ.
+1
A max.
Input Capacitance
5 pF typ
7.5 pF max.
Latch Response
Data Set Up Time
1
25 nS
Data Hold Time
2
50 nS
Strobe Pulse Width
80 nS min.
Input Data Format
Frequency Select Bits
Positive Logic
Logic "1" = +Vs
Logic "0" = Gnd
Bit Weighting
(Binary-Coded)
D
0
LSB (least significant bit)
D
7
MSB (most significant bit)
Frequency Range
256 : 1, Binary Weighted
Notes:
1.Frequency data must be present before occurrence of strobe edge.
2.Frequency data must be present after occurrence of strobe edge.
818 Series
8-Pole
Low-Pass 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
8-Bit Programmable
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
Model
818L8B
818L8L
818L8E
818L8D80
Product Specifications
Transfer Function
8-Pole,
8-Pole,
8-Pole, 6 zero,
8-Pole, 6 zero,
Butterworth Bessel
Elliptic
Constant
Delay
Size
2.0" x 4.0" x 0.4"
2.0" x 4.0" x 0.4"
2.0" x 4.0" x 0.4"
2.0" x 4.0" x 0.4"
Range f
c
1 kHz to 128 MHz
1 kHz to 1.28 MHz
1 kHz to 1.28 MHz
1 kHz to 1.28 MHz
Theoretical Transfer
Appendix A
Appendix A
Appendix A
Appendix A
Characteristics
Page 9
Page 4
Page 24
Page 21
Passband Ripple
0.0 dB
0.0 dB
0.035 dB
0.15 dB
(theoretical)
DC Voltage Gain
0 0.1 dB max.
0 0.1 dB max.
0 0.1 dB max.
0 0.1 dB max.
(non-inverting)
0 0.05 dB typ.
0 0.05 dB typ.
0 0.05 dB typ.
0 0.05 dB typ.
Stopband
Attenuation Rate
48 dB/octave
48 dB/octave
80 dB min.
80 dB min.
Cutoff Frequency
f
c
3% max.
f
c
3% max.
f
r
3% max.
f
c
3% max.
Stability
0.01% /C
0.01% /C
0.01% /C
0.01% /C
Amplitude
- 3 dB
- 3 dB
- 0.035 dB
- 3 dB
Phase
-360
-182
- 323.5
-306
Filter Attenuation
0.12 dB 0.80 f
c
1.91 dB 0.80 f
c
0.035 dB 1.00 f
r
3.01 dB 1.00 f
c
(theoretical)
3.01 dB 1.00 f
c
3.01 dB 1.00 f
c
3.01 dB 1.13 f
r
60.0 dB 3.08 f
c
60.0 dB 2.37 f
c
60.0 dB 4.52 f
c
60.0 dB 1.67 f
r
80.0 dB 3.57 f
c
80.0 dB 3.16 f
c
80.0 dB 6.07 f
c
80.0 dB 1.77 f
r
Phase Match
1
See page 5 & 6
See page 5 & 6
See page 5 & 6
See page 5 & 6
Amplitude Accuracy
0 - 0.6 f
c
0.5 dB max.
0 - f
c
0.8 dB max.
0 - 0.8 f
r
0.5 dB max.
0 - 0.8 f
c
0.5 dB max.
(theoretical)
0.25 dB typ.
0.4 dB typ.
0.25 dB typ.
0.25 dB typ.
0.6 f
c
- 1.0 f
c
1.0 dB max.
0.8 f
c
- 1.0 f
r
1.0 dB max.
0.8 f
c
- 1.0 f
c
1.0 dB max.
0.6 dB typ.
0.5 dB typ.
0.5 dB typ.
Total Harmonic
< - 88 dB typ.
< - 88 dB typ.
< - 88 dB typ.
< - 88 dB typ.
Distortion @ 1 kHz
Wide Band Noise
300
Vrms typ.
300
Vrms typ.
350
Vrms typ.
300
Vrms typ.
(5 Hz - 2 MHz)
Narrow Band Noise
75
Vrms typ.
75
Vrms typ.
75
Vrms typ.
75
Vrms typ.
(5 Hz - 100 kHz)
Filter Mounting
Assembly
FMA-04A
FMA-04A
FMA-04A
FMA-04A
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
8-Bit Programmable
818 Series
8-Pole
High-Pass Filters
4
1.Unit to unit match for the same transfer function, set to the same frequency and operating configuration, and from the same manufacturing lot.
Model
818H8B
818H8E
Product Specifications
Transfer Function
8-Pole, 8-Pole,
6-zero,
Butterworth Elliptic
Size
2.0" x 4.0" x 0.4"
2.0" x 4.0" x 0.4"
Range f
c
1 kHz to 1.28 MHz
1 kHz to 1.28 MHz
Theoretical Transfer
Appendix A
Appendix A
Characteristics
Page 29
Page 37
Passband Ripple
0.0 dB
0.035 dB
(theoretical)
Voltage Gain
0 0.5 dB to 1.28 MHz
0 0.5 dB to 1.28 MHz
(non-inverting)
Power Bandwidth
(-6 dB) 5 MHz
(-6 dB) 5 MHz
Stopband
Attenuation Rate
48 dB/octave
80 dB
Cutoff Frequency
f
c
3% max.
f
r
3% max.
Stability
0.01% /C
0.01% /C
Amplitude
- 3 dB
- 0.035 dB
Phase
-360
-323.5
Filter Attenuation
80 dB 0.31 f
c
80.0 dB 0.56 f
r
(theoretical)
60 dB 0.42 f
c
60.0 dB 0.60 f
r
3.01 dB 1.00 f
c
3.01 dB 0.88 f
r
0.00 dB 2.00 f
c
0.03 dB 1.00 f
r
00.0 dB 2.00 f
r
Amplitude Accuracy
1.0 - 1.25 f
c
0.5 dB max.
1.00 - 1.25 f
r
0.5 dB max.
(theoretical)
0.3 dB typ.
0.3 dB typ.
1.25f
c
-1.28MHz 1.0 dB max.
1.25f
r
-1.28MHz 1.0 dB max.
0.5 dB typ.
0.5 dB typ.
Total Harmonic
< - 88 dB typ.
< - 88 dB typ.
Distortion @ 1 kHz
Wide Band Noise
400
Vrms typ.
450
Vrms typ.
Narrow Band Noise
100
Vrms typ.
100
Vrms typ.
Filter Mounting
Assembly
FMA-04A
FMA-04A
1 kHz to 1.28 MHz
818 Series
Phase and Phases
Match Considerations
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
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.
EXAMPLE: Phase Match Calculation
(f)max = 0.02 x (f) + 4.0 x f/fc x fmax/1.28MHz
4.0 - L8L
3.0 - L8B & L8D80
2.0 - L8L
(f)typ =0.5 x (f)max
where:
(f) = phase match at frequency f
(f) = theoretical phase shift at f
f
= frequency of interest
f max
= maximum fc of the model
fc
= 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
(f) = 133 (from data table at f/fc = 0.5)
Phase Match:
(f)max = 0.02 x (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
(f)typ =0.5 x (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 5kHz 10kHz 20kHz 40kHz 80kHz 160kHz 320kHz 640kHz 1.28MHz
0.10
0.15
0.18
0.17
0.08
-0.12
-0.52
-1.18
-2.57
-5.32
0.20
0.30
0.32
0.30
0.17
-0.39
-1.03
-2.41
-5.17
-10.76
0.30
0.34
0.42
0.40
-0.18
-0.57
-1.59
-3.66
-7.89
-16.29
0.40
0.20
0.40
0.50
-0.20
-0.90
-2.30
-5.10
-10.80
-22.10
0.50
0.20
0.32
0.60
-0.40
-1.20
-3.00
-6.70
-14.00
-28.20
0.60
0.00
0.00 -0.10
-0.80
-1.90
-4.10
-8.70
-17.70
-35.10
0.70 -0.21 -0.30 -0.60
-1.30
-2.70
-5.40
-11.00
-21.80
-42.60
0.80 -0.50 -0.60 -1.30
-2.10
-3.80
-7.20
-13.90
-26.90
-51.30
0.85 -0.80 -1.00 -1.80
-2.80
-4.70
-8.40
-15.80
-30.10
-56.40
0.90 -1.20 -1.60 -2.50
-3.70
-5.80 -10.00
-18.40
-33.80
-62.30
0.95 -1.90 -2.40 -3.50
-4.80
-7.30 -12.00
-21.10
-38.30
-69.20
1.00 -2.50 -3.30 -4.60
-6.20
-8.90 -14.10
-24.30
-43.30
-77.50
5
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