Abstract: A latching mechanism is provided. The latching mechanism includes a first member (2) having a first catch (4) and lateral catches (6), and a second member (1) having a notch (7) and lateral catches (8). In a first position, the first catch of the first member engages the notch of the second member. In a second position, the lateral catches of the first member engage the lateral catches of the second member. Further, when in the first position, the first catch and the notch are disengaged by squeezing one of the members at lateral points while sliding the members relative to one another until the lateral catches are engaged and the members are in the second position. Also provided is a battery pack (1, 2) having such a latching mechanism. Additionally, there is provided an electronic device that includes an operational unit (3), a tray (2) for holding battery cells, and a cover (1). The tray is removably coupled to the operational unit, and the cover is removably coupled to the tray.

Abstract: A wideband level shift circuit (200) used with low voltage ECL or CML topologies. includes a sub-Vbe voltage reference (201) whose output voltage is offset some fraction of a diode voltage drop below a supply voltage, where the fraction is held at a constant value as the diode voltage varies with temperature. A comparator circuit (203) is attached to the reference voltage circuit (201) as well as to a current sourcing transistor and differential buffer circuit (205). The comparator circuit (203) maintains the DC potential at the output of a current sourcing transistor so that the common-mode DC level of the output signal from a differential buffer is shifted down by a fraction of a diode drop from the common-mode DC level of a wideband AC input signal. The shift circuit (200) offers the advantages of a fraction of a diode DC voltage drop with little loss of AC signal bandwidth for circuits operating from low supply voltages.

Abstract: An antenna shroud (100) used for covering an antenna element includes a hollow non-conductive sheath (101) attached to a base (103). The base (103) is used for holding the sheath (101) into a fixed positioned while the antenna shroud (100) is positioned within an aperture (114) located within a radio housing. The antenna shroud (100) is used to seal the antenna opening in the radio housing and for protecting the antenna element from damage. Additionally, the antenna shroud (100) also is used to protect a user from coming into direct contact with radio frequency energy radiated by the antenna element.

Abstract: A direct current (DC) offset correction loop (200) for determining the required amount of DC offset to an analog input signal includes a digital integrator (211) for measuring the amount of DC offset present at the final output of a forward signal path and a hold circuit (213) for controlling the digital integrator (213). The DC offset correction loop (200) provides a constant amount of DC offset correction to the analog input signal.

Abstract: A frequency generating circuit scales a warp range of a frequency signal. The frequency generating circuit includes a first frequency signal (10) having a first offset signal with a first frequency relationship to the first frequency signal, and a second frequency signal (14). A frequency scaling element (16) receives the first frequency signal (10) and second frequency signal and provides a third frequency signal, such that the third frequency signal includes the first offset signal having a second frequency relationship to the third signal. A switch (54), has a control input (74), a first input for receiving the first frequency signal, a second input operably coupled to the frequency scaling element (16, 42) for receiving the third frequency signal and an output (76) operably coupled to the first input or the second input dependent upon a control signal applied to the control input (74).

Abstract: An integrated multi-mode bandpass sigma-delta radio frequency receiver subsystem with interference mitigation includes a first intermediate frequency amplifier. At least one mixer for mixing the output of the first amplifier and an oscillator signal. A second IF amplifier for amplifying and filtering the output of the at least one mixer. A multi mode multi bandwidth sigma delta analog digital converter for providing digital output signals with high dynamic range. A digital mixer providing I and Q signals a decimation network providing I and Q signals at reduced programmable data and clock frequencies and a formatting network for arranging the I and Q signals into a predetermined format for use with a digital signal processor.

Abstract: A tuned low noise mixer (200) for use in radio frequency (RF) communications includes a transconductance amplifier (203) for amplifying an RF input signal (201). An impedance matching network (207) is formed using an impedance matching transformer with a tap connection (207') between primary and secondary coils. A mixer circuit (209) is then used for mixing a local oscillator signal (211) with the output of the impedance matching network (207) while a load network (213) provides a load to an output (215) of the mixer circuit (209). The invention provides a novel RF mixer topology that has a substantially low noise figure and a proportionally large power gain with low current drain for eliminating the need for an low noise amplifier (LNA) commonly used in RF mixer circuitry.

Abstract: The method of the present invention produces a plurality of bi-level waveforms on the ROW/common lines and COLUMN/segment lines of a passive multiplexed liquid crystal display (LCD). These waveforms drive the LCD display using binary data from display memory locations. At periodic intervals a counter is incremented while the counter value is then used to 1) look-up in a table the bi-level data to output on the ROW/commons; 2) look-up memory locations associated with the active COLUMN/segments; and 3) to provide inverted COLUMN/segments data before sending the bi-level data to the COLUMN/segment lines of the LCD. The counter increments from zero to four times the number of ROW/commons before being reset to zero and the waveforms repeated. Thus, an algorithm produces one ON/select voltage and one OFF/non-select voltage that are provided to the LCD.

Abstract: A housing (101) for a portable two-way radio (100) includes a first aperture (107) located substantially at one end of the housing (101) for engaging an first attachment apparatus such as a belt clip (201). A second aperture (111) is located substantially at the opposite end of the radio housing (101) for engaging a second attachment apparatus. The first aperture (107) and the second aperture (111) are used with the belt clip (201) such that the clip may be secured within either the first aperture (107) or second aperture (111) for attachment to a user's body or other object. The attachment of the belt clip (201) is unique in that it can be bent without being disengaged from its associated aperture.

Abstract: The invention concerns a method and apparatus for providing frequency control of an oscillator circuit. The apparatus includes an oscillator (9), an error estimator (10) f.sub.r producing a set of error estimates and a median filter (11) for producing a median value from the set of estimates. The median filter (11) is connected to the oscillator (9) which is responsive to the median value to vary its frequency thereby reducing the error.

Abstract: A method of multiplex driving a passive liquid crystal display (LCD) using a bi-level LCD multiplex driver for providing one or more bi-level waveforms on the ROW/common lines and COLUMN/segment lines of a multiplexed liquid crystal display (LCD). These waveforms drive the LCD display using binary data from display memory locations. At periodic intervals the machine state is advanced with the present state used to 1) look-up in a table the bi-level data to output on the ROW/commons, and 2) look-up memory locations associated with the active COLUMN/segments; and 3) to provide inverted COLUMN/segments data before sending the bi-level data to the COLUMN/segment lines of the LCD. The states advance four times the number of ROW/commons before being reset to the initial state and the waveforms repeated. Thus, the machine produces one ON/select voltage and one OFF/non-select voltage are provided to the LCD according to predetermined formulas.

Abstract: A voltage controlled oscillator circuit (58) having a modulation input port (60) for receiving a modulation input signal through modulation circuit (62, 64, 66, 68) and a frequency resonator circuit (28, 74, 76, 80, 82, 84) operable coupled to the modulation input port (60) for providing a modulation dependent impedance. A semiconductor element (90) has three ports, a gate port (98), a source port (96) and a drain port (92), and the modulation circuit is operably coupled to the gate port (98) of the field effect transistor (90) via a first capacitance (70) and the source port (96) of the field effect transistor (90) via a second capacitance (71). This enables the modulation sensitivity to be substantially independent of temperature variations of circuit elements.

Abstract: A double resonant wideband patch antenna (100) includes a planar resonator (101) forms a substantially trapezoidal shape having a non-parallel edge (103) for providing a substantially wide bandwidth. A feed line (107) extends parallel to the non-parallel edge (103) for coupling while a ground plane (111) extends beneath the planar resonator for increasing radiation efficiency.

Abstract: A belt clip (100) use with an electronic device includes an attachment member (101) for securing the electric device to a fixed object such as a person's belt. The attachment member (101) includes a protective cover retention area (107) for enabling a protective cover (13), that is used as a port or dust cover for protecting unused electrical connectors, to be frictionally engaged therein.

Abstract: A wideband level shift circuit (200) used with low voltage ECL or CML topologies includes a sub-Vbe voltage reference (201) whose output voltage is offset some fraction of a diode voltage drop below a supply voltage, where the fraction is held at a constant value as the diode voltage varies with temperature. A comparator circuit (203) is attached to the reference voltage circuit (201) as well as to a current sourcing transistor and differential buffer circuit (205). The comparator circuit (203) maintains the DC potential at the output of a current sourcing transistor so that the common-mode DC level of the output signal from a differential buffer is shifted down by a fraction of a diode drop from the common-mode DC level of a wideband AC input signal. The shift circuit (200) offers the advantages of a fraction of a diode DC voltage drop with little loss of AC signal bandwidth for circuits operating from low supply voltages.