摘要:
A temperature compensated crystal oscillator (10), has a crystal oscillator circuit (12), a voltage controlled reactance element (30), a temperature compensation network (50), and a programmable DC-DC converter network (60) having an output (62) connected to the voltage controlled reactance element (30), or the temperature compensation network (50) or both. The DC-DC converter network (60) provides the capability of operating over an extended voltage range, by increasing the supply voltage to a level necessary to operate the voltage controlled reactance element (30). Much of this structure is adapted for use in an integrated circuit, and provides the advantages of minimizing power and current consumption.
摘要:
A low current oscillator/buffer amplifier configuration is disclosed which provides a simple, inexpensive, low power oscillator with reduced harmonic output. Buffer 60 is coupled to the resonant tank circuit 58 of oscillator 50 by means of impedance transform network 70. This technique of tapping directly from the tank provides a buffered output signal having low harmonic content. Furthermore, impedance transform network 70 permits coupling feedback amplifier 52 to buffer amplifier 62 in a totem-pole amplifier stage configuration. This feature provides a significant current savings over conventional oscillator/buffer circuits. The instant invention is particularly well adapted for use as reference frequency oscillators in portable radio applications.
摘要:
A method within adjusting values of a passive temperature compensation network for use in an oscillator includes the steps of determining the frequency variation of the oscillator from nominal over a specified temperature range, determining the maximum frequency variation over the temperature range, and recalculating the performance of the circuit over the temperature range utilizing reduced values for the temperature compensation components therein. The oscillation frequency can be utilized as the controlled parameter to a laser based component trimming system. Power is applied to the oscillator and the compensation component is trimmed until the circuit oscillates at the specified target frequency.
摘要:
Heat-generating ovenized crystal oscillators can be directly mounted to a circuit board. Thermal isolation of an OCO from heat-sinking circuit board material and other temperature-sensitive components on a circuit board is accomplished by means of perforations (12) in the circuit board that surround the mounting area of the OCO on the board.
摘要:
A controllable crystal oscillator includes a crystal resonator having first and second electrodes, a gain stage having first and second terminals connected to the first and second electrodes for starting and maintaining the oscillation, first and second capacitor banks connected to the first and second terminals for providing a capacitive load to the resonator, and first and second dynamic switches interconnected between the terminals and the respective capacitor banks for cycling the capacitor banks in and out of connection.
摘要:
A modified temperature compensation signal (110) is provided in a temperature compensated crystal oscillator (TCXO) circuit (100) in the following manner. A temperature dependent current generator (104) produces a temperature compensation signal (108) whose amplitude changes responsive to changes in ambient temperature. The temperature compensation signal (108) is scaled, based on a plurality of discrete frequency adjust values (212), to produce the modified temperature compensation signal (110).