US3727154A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bandpass filter including monolithic crystal elements and resistive elements
Assignee: Motorola Solutions Inc
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Filing: 1970-12-16
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Granted: 1973-04-10
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Expires: 1990-12-16
Abstract
Abstract A bandpass filter circuit includes a pair of monolithic crystal filter elements and a resistance-capacitance network, which may be a lattice network, connected between the crystal filter elements. The crystal filter elements are dual-coupled resonators which have a pair of resonator spots formed on a quartz wafer, and the resonators have relatively well defined bandpass characteristics extending above and below their resonant frequencies and provide an abrupt change in attenuation at the limits of the bandpass frequencies. The resistance-capacitance network used with the crystal filter elements acts to relocate the pole frequencies so that the characteristic curve of the complete filter closely approximates a Gaussian shape in the vicinity of the bandpass. The bandpass filter circuit thus formed is particularly adapted for use in a mobile receiver where extraneous undesired signals may occur in the crystal filter elements resulting from impulse type signals, such as that produced by spark discharge of the ignition system, and these undesired signals are greatly reduced or eliminated.
Inventors
- 👤 C Livenick
- 👤 J Dailing
- 👤 S Malinowski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:53
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H03H9/54; H03H9/545
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
257 words
A bandpass filter circuit for passing frequencies within a predetermined passband, including in combination, first and second resonators each including a single crystal wafer and electrode means cooperating therewith to form at least two separate resonating portions each including a pair of electrodes on opposite sides of said wafer, input signal means coupled to said pair of electrodes of the first resonating portion of said first resonator for applying therebetween signals including signals which fall within said predetermined passband of the filter circuit, each of said first and second resonAtors acting to couple signals through said wafer thereof from said first resonating portion to said second resonating portion thereof, a coupling circuit connected from said pair of electrodes of said second resonating portion of said first resonator to said pair of electrodes of said first resonating portion of said second resonator for coupling signals from said second resonating portion of said first resonator to said first resonating portion of said second resonator, said coupling circuit including resistance means connected in series circuit with said pair of electrodes of said second resonating portion of said first resonator and said pair of electrodes of said first resonating portion of said second resonator, said resistance means having a value such that the characteristic curve of the filter circuit in the passband is substantially of symmetrical Gaussian shape to reduce undesired impulse-type signal transients, and means coupled to said pair of electrodes of said second resonating portion of said second resonator for receiving the signal translated through the bandpass filter circuit.
Claim 2
Dependent Claim
257 words
A bandpass filter circuit for passing frequencies within a predetermined passband, including in combination, first and second resonators each including a single crystal wafer and electrode means cooperating therewith to form at least two separate resonating portions each including a pair of electrodes on opposite sides of said wafer, input signal means coupled to said pair of electrodes of the first resonating portion of said first resonator for applying therebetween signals including signals which fall within said predetermined passband of the filter circuit, each of said first and second resonAtors acting to couple signals through said wafer thereof from said first resonating portion to said second resonating portion thereof, a coupling circuit connected from said pair of electrodes of said second resonating portion of said first resonator to said pair of electrodes of said first resonating portion of said second resonator for coupling signals from said second resonating portion of said first resonator to said first resonating portion of said second resonator, said coupling circuit including resistance means connected in series circuit with said pair of electrodes of said second resonating portion of said first resonator and said pair of electrodes of said first resonating portion of said second resonator, said resistance means having a value such that the characteristic curve of the filter circuit in the passband is substantially of symmetrical Gaussian shape to reduce undesired impulse-type signal transients, and means coupled to said pair of electrodes of said second resonating portion of said second resonator for receiving the signal translated through the bandpass filter circuit.
Claim 3
Dependent Claim
56 words
The bandpass filter circuit of claim 1 wherein said crystal wafers of said first and second resonators are made of quartz, and said resistance means is a single resistor connected in series between one electrode of said second resonating portion of said first resonator and one electrode of said first resonating portion of said second resonator.
Claim 4
Dependent Claim
75 words
The bandpass filter circuit of claim 1 wherein said resistance means is formed of first and second resistors connected in an L-pad configuration, with said first resistor connected in series between one electrode of said second resonating portion of said first resonator and one electrode of said first resonating portion of said second resonator, and with said second resistor connected in shunt relation with said electrodes of said second resonating portion of said first resonator.
Claim 5
Dependent Claim
29 words
The bandpass filter circuit of claim 1 wherein said resistance means includes a resistor connected in series with said electrodes of said second resonating portion of said first resonator.
Claim 6
Dependent Claim
29 words
The bandpass filter circuit of claim 1 wherein said resistance means includes a resistor connected in series with said electrodes of said first resonating portion of said second resonator.
Claim 7
Dependent Claim
49 words
The bandpass filter circuit of claim 1 wherein said resistance means includes a first resistor connected in series with said electrodes of said second resonating portion of said first resonator, and a second resistor connected in series with said electrodes of said first resonating portion of said second resonator.
Claim 8
Dependent Claim
48 words
The bandpass filter circuit of claim 1 wherein said resistance means includes a first resistor connected in series with said electrodes of said second resonating portion of said first resonator, and a second resistor connected in parallel with said first resistor and its associated series connected resonating portion.
Claim 9
Dependent Claim
48 words
The bandpass filter circuit of claim 1 wherein said resistance means includes a first resistor connected in series with said electrodes of said first resonating portion of said second resonator, and a second resistor connected in parallel with said first resistor and its associated series connected resonating portion.
Claim 10
Dependent Claim
70 words
The bandpass filter circuit of claim 1 wherein said resistance means includes a first resistor connected in series with said electrodes of said second resonating portion of said first resonator, a second resistor connected in series with said electrodes of said first resonating portion of said second resonator, and a third resistor connected in shunt relation with said first and second resistors and their respective associated series connected resonating portions.
Claim 11
Dependent Claim
259 words
In a bandpass filter circuit for passing frequencies within a predetermined passband which includes first and second resonators each having first and second resonating portions with a pair of electrodes, input signal means coupled tO the electrodes of the first resonating portion of the first resonator for applying therebetween signals including signals which fall within said predetermined passband of the filter circuit, a coupling circuit for coupling signals from the electrodes of the second resonating portion of the first resonator to the electrodes of the first resonating portion of the second resonator, and means coupled to the electrodes of the second resonating portion of the second resonator for receiving the signal translated therethrough; the improvement wherein each of the first and second resonators comprises a single quartz crystal wafer and first and second pairs of electrodes thereon forming first and second resonating portions, with each pair including electrodes on opposite sides of said wafer, each of said first and second resonators acting to couple signals through said wafer thereof from said first resonating portion to said second resonating portion thereof, and wherein said coupling circuit includes resistance means and capacitance means, with said resistance means being connected in series circuit with said pair of electrodes of said second resonating portion of said first resonator and with said pair of electrodes of said first resonating portion of said second resonator, said resistance means having a value such that the characteristic curve of the filter circuit in the passband is of substantially symmetrical Gaussian shape to reduce undesired impulse-type signal transients.
Claim 12
Dependent Claim
259 words
In a bandpass filter circuit for passing frequencies within a predetermined passband which includes first and second resonators each having first and second resonating portions with a pair of electrodes, input signal means coupled tO the electrodes of the first resonating portion of the first resonator for applying therebetween signals including signals which fall within said predetermined passband of the filter circuit, a coupling circuit for coupling signals from the electrodes of the second resonating portion of the first resonator to the electrodes of the first resonating portion of the second resonator, and means coupled to the electrodes of the second resonating portion of the second resonator for receiving the signal translated therethrough; the improvement wherein each of the first and second resonators comprises a single quartz crystal wafer and first and second pairs of electrodes thereon forming first and second resonating portions, with each pair including electrodes on opposite sides of said wafer, each of said first and second resonators acting to couple signals through said wafer thereof from said first resonating portion to said second resonating portion thereof, and wherein said coupling circuit includes resistance means and capacitance means, with said resistance means being connected in series circuit with said pair of electrodes of said second resonating portion of said first resonator and with said pair of electrodes of said first resonating portion of said second resonator, said resistance means having a value such that the characteristic curve of the filter circuit in the passband is of substantially symmetrical Gaussian shape to reduce undesired impulse-type signal transients.
Claim 13
Dependent Claim
40 words
The combination of claim 10 wherein said capacitance means includes a first capacitor connected across said electrodes of said second resonating portion of said first resonator, and a second capacitor connected across said first resonating portion of said second resonator.
Claim 14
Dependent Claim
40 words
The combination of claim 11 wherein said resistance means is a single resistor connected in series between one electrode of said second resonating portion of said first resonator and one electrode of said first resonating portion of said second resonator.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-09 | 1976-10-09 | 1977-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-09 | 1980-10-09 | 1981-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-09 | 1984-10-09 | 1985-04-10 | $7700.00 | Window Closed / Lapsed |