General Electric Company

Ericsson Ge Mobile Communications Inc.

Ericsson Gmbh

Xtal Technologies, Ltd.

Gerald E Roberts

Samuel Toliver

Robert J Crescenzi

Alfred G Staples

Michael E Roberts

Johannes J Vandegraaf

John R Lane

John R Poirier

William P Overstreet

John U Daniels, Jr

Robert B Sanders

A Gordon Staples

Fulvio Bonecchi

David Bing

Samual Toliver

Myron A Turner, Jr

Jeff Johnson

Harry J Peppiatt

A passive bandpass tracking filter tracks the frequency of an RF input signal received within a radio receiver's tracking range of RF frequencies. The bandpass filter includes parallel inductor and capacitor circuits connected in shunt between the input and output filter ports. A tracking control signal is selectively applied to change the capacitance of the LC circuits in order to shift the filter's frequency characteristics/profile as the filter tracks through the tracking band. The filter attenuates half-IF, receiver IF, and image spurious signals. In particular, the filter substantially attenuates the image spurious signal throughout the tracking frequency range by 50 dB or more below the filter output signal level. The filter also attenuates the half-IF spurious signal throughout the tracking frequency range by well over 10 dB or more below the filter output signal level. The receiver IF spurious signal is attenuated about 40 dB. The bandpass tracking filter has both a low insertion loss of about 5.0 dB or less and a substantially constant insertion loss variance at the RF receive frequency of about 1 dB or less over the entire tracking frequency range.

Radio frequency tracking filter

An architecture and frequency plan for a wideband UHF radio minimizing spurious output signal emissions uses a low value for the ratio of the maximum RF operating frequency to the (first) intermediate frequency (IF) in the radio, as part of its internal superheterodyne conversion process. A minimum value or a value sufficiently close to the minimum value of this ratio allows the radio design to be optimized to reduce spurious outputs and the effects of inherently present major harmonics. These and other advantages and features permit a radio design to be realized in a cost effective manner for an array of stringent performance specifications including low spurious output emissions.

Architecture and frequency plan for a UHF portable radio

The present invention discloses a method for obtaining frequency parameters to determine the resonator frequencies, the synchronous peak separation frequency, and the normal center frequency of a coupled-dual resonator crystal. Under this method, a plurality of frequencies are applied to a first electrode. This application is performed once while the second electrode and the common electrode are connected by a short circuit, and then again when the second electrode and the common electrode are capacitively connected or open circuited. During each application of the plurality of frequencies to the crystal, the phase response for the output of the resonator circuit is monitored. Then the time response of the crystal is determined. Next, the time delay relative maxima for the time response is determined. Finally, the frequencies at which the time delay relative maxima occur are determined. These frequencies correspond to the inflection points where the change in phase goes from monotonically increasing to monotonically decreasing. These frequencies are used to calculate the resonator frequencies, the synchronous peak separation frequency, and the normal center frequency of the crystal. Alternatively, all of the critical frequencies can be determined with the second electrode and the common electrode connected by a short circuit. In this case, however, the critical frequencies correspond to the time delay maxima and minima for the time response. This method is applicable regardless of the frequencies of the resonators or the amount of frequency separation between the resonators.

Method for measuring selected frequencies of a coupled-dual resonator

The present invention discloses a method for obtaining frequency parameters to determine the resonator inductances of a crystal. Under this method, a plurality of frequencies are applied to a first electrode. This application is performed once while the second electrode and the common electrode are connected by a short circuit, and then again when the second electrode and the common electrode are capactively connected or open circuited. During each application of the plurality of frequencies to the crystal, the phase response for the output of the resonator circuit is monitored. Then the time response of the crystal is determined. Next, the time delay relative maxima for the time response is determined. Finally, the frequencies at which the time delay relative maxima occur are determined. These frequencies correspond to the inflection points where the change in phase goes from monotonically increasing to monotonically decreasing. This process is repeated with the crystal turned around in the test fixture to obtain a second set of frequencies. These frequencies are then used to calculate the resonator inductances of the crystal. Alternatively, all of the critical frequencies can be determined with the second electrode and the common electrode connected by a short circuit. In this case, however, the critical frequencies correspond to the time delay maxima and minima for the time response. This method is applicable regardless of the frequencies of the resonators or the amount of frequency separation between the resonators.

Method for measuring the inductance of each resonator of a coupled-dual

A clip for surface-mounting a coupled-dual resonator crystal to a circuit board includes an elongated housing shaped complementary to the housing of the crystal and having an opening along a side for receiving the crystal. A tab spaces first and second shielding portions which overlie the end of the crystal housing. A first shield portion engages the middle ground terminal of the crystal shielding the input and output terminals, while the second shield extends from the first shield to overlie the output terminal, likewise shielding it from the input terminal. Distal portions of the input, output and common terminals, together with pads at the opposite end of the clip, mount the clip mechanically to the surface of a circuit board.

Attachment for surface-mounting a resonator crystal on a circuit board

A monolithic coupled-dual resonator crystal filter coupled to improve switching arrangements is tested using both resonator ports to quickly measure selected resonator parameters useful in frequency adjustment, production and test systems as well as accurately measuring other filter crystal parameters, all without requiring removal of the crystal structure from the test fixture.

Switching arrangement method and apparatus for making parameter

In coupled-dual resonator crystals, key parameters, such as resonator frequencies and synchronous peak separation frequency, are determined using a four frequency measuring process and apparatus wherein additional impedance is connected in parallel with the driving point impedance of the input resonator so as to allow the measurement of the critical frequencies above about 45 MHz.

Method and apparatus for parameter measurement of coupled-dual resonator

A third case or manner of obtaining the four critical frequencies useful in accurately measuring coupled-dual resonator crystals, wherein both ports of the crystal structure are monitored, rather than a single port in the previously known cases. Here the B port, for example, is monitored with the A-side open-circuited or with a capacitor in parallel with it, and the A port is monitored with the B-side short-circuited.

Method and apparatus for implementing four-frequency measuring process

A monolithic coupled-dual resonator crystal filter is produced for operation with wide bandwidths (especially at high center frequencies) by providing an ultra-small gap between juxtaposed resonator electrodes. A gap width of substantially less than 0.006 inch is obtained by laser-machine trimming the gap. An initial single electrode may thus be divided into a pair of such juxtaposed resonator electrodes. Further metallic plate-back is provided on the electrodes for center-frequency control. Although this typically may decrease the coupling bandwidth somewhat, an increased thickness of metallic plate-back material on the ground electrode, opposite the ultra-thin gap area on the active side of the crystal wafer, provides precisely controlled extra wide bandwidth.

Monolithic crystal filter with wide bandwidth and method of making same

A dual-coupled resonator crystal is fine-tuned by frequency balancing the input and output resonators and thereafter plating a coupling adjust spot on the grounded side shadowing the unelectroded region of the front side of the crystal to produce a change in synchronous peak separation frequency. Thereafter, the front side electrodes are sequentially plated to bring plateback and synchronous peak separation frequency to their target values. Interim adjustments in synchronous peak separation frequency may be made during the tuning process to compensate for misalignment of the plating elements.

Coupled-dual resonator crystal

Method and apparatus for selectively fine-tuning a coupled-dual

A system for plating resonator electrodes or the like by the vapor deposition process employs one or more shutters between the deposition material source and a plating mask. At least one of the shutters has a pair of apertures aligned with different apertures in the plating mark. In one embodiment comprising a two shutter, four position system, the two shutters may be positioned such that either, both or neither of the resonators can be plated. Because each shutter is either ON or OFF, a simple binary analogy for control of the shutters results.

Shutter apparatus for fine-tuning a coupled-dual resonator crystal

A multi-resonator crystal body is physically supported by electrical lead wires extending from a support substrate having individual shaped electrical conductors thereon which are thus connected to each resonator on the crystal body such that the individual resonator electrodes can be selectively short-circuited, or open-circuited, or displayed to an external electrical network to facilitate final finishing of the resonator electrodes. Predetermined electrical circuits (e.g. a short-circuit effected by conductive cement or paint) are thereafter connected across some of the resonator electrodes via the shaped conductive areas on the support substrate before the entire assembly is encapsulated in a standard pin connector housing arrangement. Besides greatly facilitating the tuning of individual crystal resonators to desired frequencies during the finishing operation, this mounting arrangement is also believed to provide improved temperature characteristics and/or shock mounting of the crystal body.

Monolithic crystal filter and method of manufacturing same

An improved crystal is provided with an aluminum baseplate, a nickel plating on the aluminum baseplate, and a silver plating on the nickel plating. The nickel is plated on the aluminum baseplate before the aluminum has oxidized to provide high yields of stable crystals.

Piezoelectric crystal electrodes and method of manufacture

A crystal filter structure and fabrication method therefor. The crystal filter is constructed as a thick film circuit on a ceramic substrate. The coupling capacitors are painted on the ceramic substrate as part of the thick film circuit. The capacitors are laser trimmed to precise tolerance in order to provide a crystal filter having precise characteristics.

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Lynchburg, VA, United States of America

Gerald E Roberts