External component programming for crystal oscillator temperature compensation
First Claim
1. A temperature compensated crystal oscillator circuit, comprising:
- a temperature compensation circuit, a crystal oscillator, a voltage variable reactance, an A/D converter, and an external discrete component, the component being coupled in one of a voltage divider and a current driver stage, the voltage variable reactance being coupled to the crystal oscillator and the temperature compensation circuit;
the discrete component being selected to generate a predetermined voltage, the voltage being coupled to the A/D converter which produces a set of digital signals, the digital signals correlating to the predetermined voltage and being coupled to the temperature compensation circuit such that a desired temperature compensation signal is produced; and
the compensation signal driving the voltage variable reactance which reactively loads the crystal oscillator such that an output frequency from the crystal oscillator remains substantially constant over a desired range of temperatures.
2 Assignments
0 Petitions
Accused Products
Abstract
A temperature compensation circuit (10) for a crystal oscillator programmed by a single component (12), such as a resistor. The component (12) provides a voltage to an A/D converter (26). The digital signals (28) from the A/D converter (26) are divided and directed to separate signal generators (44,46,48,50,56) which control different aspects of the temperature compensation circuit (10). These aspects include a hot, cold, linear, balance and warp adjustment. The temperature compensation circuit (10) drives a varactor (18) which reactively loads a crystal oscillator (14) to compensate frequency over temperature. By using a single component (12) to program the circuit (10), an EEPROM is no longer needed which saves IC space and reduces IC processing steps, and the use of multiple external components to perform a compensation is avoided which further saves physical space.
-
Citations
22 Claims
-
1. A temperature compensated crystal oscillator circuit, comprising:
-
a temperature compensation circuit, a crystal oscillator, a voltage variable reactance, an A/D converter, and an external discrete component, the component being coupled in one of a voltage divider and a current driver stage, the voltage variable reactance being coupled to the crystal oscillator and the temperature compensation circuit; the discrete component being selected to generate a predetermined voltage, the voltage being coupled to the A/D converter which produces a set of digital signals, the digital signals correlating to the predetermined voltage and being coupled to the temperature compensation circuit such that a desired temperature compensation signal is produced; and the compensation signal driving the voltage variable reactance which reactively loads the crystal oscillator such that an output frequency from the crystal oscillator remains substantially constant over a desired range of temperatures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. A temperature compensated crystal oscillator circuit, comprising:
-
a temperature compensation circuit, a crystal oscillator, a varactor, an A/D signal generator, and a resistor having a low temperature coefficient of resistance, the resistor being coupled in a current driver stage, the varactor being coupled to the crystal oscillator and the temperature compensation circuit; the resistor being selected to generate a predetermined voltage, the voltage being coupled to the A/D signal generator which produces a set of digital signals, the digital signals correlating to the predetermined voltage and being coupled to the temperature compensation circuit such that a desired temperature compensation signal is produced; and the compensation signal driving the varactor which reactively loads the crystal oscillator such that an output frequency from the crystal oscillator remains substantially constant over a desired range of temperatures. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
-
-
22. A communication device, comprising:
-
a receiver circuit; a local oscillator circuit for generating local oscillator signals including a reference oscillator comprising; a temperature compensation circuit, a crystal oscillator, a voltage variable reactance, an A/D converter, and an external discrete component, the component being coupled in one of a voltage divider and a current driver stage, the voltage variable reactance being coupled to the crystal oscillator and the temperature compensation circuit; a predetermined voltage generated at the component, the voltage being coupled to the A/D converter which produces a set of digital signals, the digital signals correlating to the predetermined voltage and being coupled to the temperature compensation circuit such that a desired temperature compensation signal is produced; and the compensation signal driving the voltage variable reactance which reactively loads the crystal oscillator such that an output frequency from the crystal oscillator remains substantially constant over a desired range of temperatures.
-
Specification