US3603898A
Expired / Lapsed
US
⏱️ 0.0 years remaining
N-parallel-path capacitive switched filter in which only incomplete spaced portions of input signal are sampled
Assignee: BAE Systems Electronics Ltd
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Filing: 1970-02-02
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Granted: 1971-09-07
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Expires: 1990-02-02
Abstract
Abstract The invention provides a band-stop filter including a plurality n of switchably selectable capacitive parallel paths. Switch means are provided for sequentially and selectively selecting the paths, the switch means being controlled to select each path for a period of time which is less than 1/nth (usually 1/4n) of the period of a complete switching sequence of all of the paths.
Inventors
- 👤 John Howard Dawson
- 👤 David George Francis Fripp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:48
CPC Classifications
H; H03; H03H; H03H19/00; H03H19/002
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
74 words
A band-stop filter including a plurality n of switchably selectable capacitive parallel paths, means for sequentially and repeatedly selecting said paths wherein each path Is selected for a period of time which is less than 1/nth of the period of a complete switching sequence of all of said paths, a common shunt impedance at the output end of said paths, and a low pass filter through which output from the band-stop filter is taken.
Claim 2
Dependent Claim
74 words
A band-stop filter including a plurality n of switchably selectable capacitive parallel paths, means for sequentially and repeatedly selecting said paths wherein each path Is selected for a period of time which is less than 1/nth of the period of a complete switching sequence of all of said paths, a common shunt impedance at the output end of said paths, and a low pass filter through which output from the band-stop filter is taken.
Claim 3
Dependent Claim
35 words
A filter as claimed in claim 1 wherein each path is selected for a period of time which is equal to 1/4n of the period of a complete switching sequence of all of said paths.
Claim 4
Dependent Claim
50 words
A band-stop filter as claimed in claim 2 wherein there is provided sampling and holding means connected and arranged to hold the output signal of a selected path substantially level during the period which follows the switching off of that path and during which none of the paths are selected.
Claim 5
Dependent Claim
48 words
A band-stop filter as claimed in claim 3 wherein the sampling and holding means is included between said common shunt impedance at the output ends of said paths and said low pass filter through which output from the band-stop filter is taken, said shunt impedance being a resistor.
Claim 6
Dependent Claim
68 words
A band-stop filter as claimed in claim 3 wherein the sampling and holding means consists of a series connected switch which, when closed, applies output signals from said paths to charge a shunt connected capacitor, said series connected switch being so controlled as to be closed during periods in which any of the paths is selected and open during periods in which none of said paths is selected.
Claim 7
Dependent Claim
32 words
A band-stop filter as claimed in claim 5 wherein the control of the series connected switch is such that it is closed after a short delay following the selection of each path.
Claim 8
Dependent Claim
25 words
A band-stop filter as claimed in claim 6 wherein the delay is substantially one quarter of the time period during which the path is selected.
Claim 9
Dependent Claim
36 words
A band-stop filter as claimed in claim 5 wherein the control of the series connected switch is such that it is opened at approximately the middle of the time period during which a path is selected.
Claim 10
Dependent Claim
24 words
A band-stop filter as claimed in claim 5 wherein means are provided for adjusting the time of opening of the said series connected switch.
Claim 11
Dependent Claim
63 words
A band-stop filter as claimed in claim 1 wherein the band-stop filter is provided with sampling and holding means which precede the plurality of switchably selectable capacitive parallel paths, and are adapted and arranged to sample an input waveform prior to a path being selected and to hold the sampled value thereof substantially level during the period in which said path is selected.
Claim 12
Dependent Claim
43 words
A band-stop filter as claimed in claim 10 wherein the sampling and holding means is arranged to sample the input waveform during each period in which none of the paths are selected and to hold the samples value substantially level between consecutive samples.
Claim 13
Dependent Claim
42 words
A band-stop filter as claimed in claim 10 wherein the sampling and holding means comprises a series connected switch which when closed, applies the input waveform to charge a shunt connected capacitor which is connected to apply voltage thereacross to said paths.
References Cited (Backward Citations)
US2584986A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-06 | 1975-03-08 | 1975-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-06 | 1979-03-08 | 1979-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-06 | 1983-03-08 | 1983-09-07 | $7700.00 | Window Closed / Lapsed |