Abstract: A crystal amplifier for driving a crystal to oscillate at a resonant frequency including a controlled current source, a primary amplifier core, a high gain amplifier core, and a controller. Both amplifier cores are coupled in parallel, and each has an input coupled to an amplifier input node and an output coupled to an amplifier output node coupled across the crystal. The current source provides a core bias current to the source node. The controller enables the high gain amplifier core and sets the core bias current to a high current level to achieve a high negative resistance at a startup time, and then disables the high gain amplifier core and sets the core bias current to a lower steady state current level after oscillation is achieved. A level detector may be used for detecting oscillation and for determining when to adjust the core bias current.

Abstract: A crystal amplifier for driving a crystal to oscillate at a resonant frequency including a current source, an amplifier, and at least one degeneration resistor. The amplifier has an input coupled to an amplifier input node and has an amplifier output current path coupled the amplifier output node. Each degeneration resistor is coupled in series with the amplifier output current path. The current source provides a core bias current through the amplifier output current path and through each degeneration resistor to a reference node. The resistance of each degeneration resistor may be selected to minimize a frequency shift over an operating temperature range while maintaining at least one operating parameter within predetermined operating limits, or can be selected based on a crystal type. Each degeneration resistor may be fixed or adjustable.

Abstract: A crystal driver integrated circuit with external oscillation signal amplitude control including an amplifier core, an input pin and an output pin, an adjustable capacitor, and a controller. The controller operates the amplifier core in any one of multiple operating modes including an oscillator mode and a bypass mode. During the bypass mode, the controller disables the amplifier core and adjusts the adjustable capacitor so that an amplitude of an oscillation signal received via the input pin from an external oscillator has a target amplitude. The external oscillation signal may be capacitively coupled for capacitive voltage division or directly coupled for impedance attenuation. An available voltage may be provided as a source voltage to the external oscillator via the output pin. An internal voltage regulator and/or switch may be included to re-provision the output pin to provide the source voltage during the bypass mode.

Abstract: A rotary vessel for a filter assembly has a rotor body rotatable about an axis of rotation and a spigot, integral or coupled with the rotor body, extending away from the rotary body along the axis of rotation. The spigot has an abutment surface against which, in use, a cooperating surface of the filter assembly abuts to inhibit movement of the rotary vessel relative to the cooperating surface and parallel to the axis of rotation. The filter assembly has a housing with main body and closure member separably attachable to the main body. The closure member retains the rotary vessel inside the housing and is separable from the main body to permit removal of the rotary vessel from the housing. A connector releasably couples the closure member to the rotary vessel such that the rotary vessel is removable from the housing by separating closure member and main body.

Abstract: A rotary vessel for a filter assembly has a rotor body rotatable about an axis of rotation and a spigot with a non-circular cross-section and integral with or coupled to the rotor body. The spigot extends away from the rotor body along the axis of rotation and engages with a bearing. The spigot facilitates transfer of rotary motion between the rotor body and the bearing. A filter assembly has a housing with a main body and a closure member separably attachable to the main body. The rotary vessel is disposed inside the housing. The closure member retains the rotary vessel inside the housing and is separable from the main body to permit removal of the rotary vessel from the housing. The spigot integral with or coupled to the rotor vessel engages with a bearing of the filter assembly to rotatably support the rotary vessel in the housing.

Abstract: A ring detect circuit is shown that includes a regenerative latch configured to be coupled to a telephone line. The regenerative latch is configured to generate a fast transient signal in response to a ring signal on the telephone line. The latch is coupled to an isolation transformer through a capacitor. The fast transient passes across the capacitor and through the transformer. A comparator detects the fast transient and, responsive thereto, generates a ring detect signal.

Abstract: A ring detect circuit is shown that includes a regenerative latch configured to be coupled to a telephone line. The regenerative latch is configured to generate a fast transient signal in response to a ring signal on the telephone line. The latch is coupled to an isolation transformer through a capacitor. The fast transient passes across the capacitor and through the transformer. A comparator detects the fast transient and, responsive thereto, generates a ring detect signal.