The frequency error of an oscillator is minimized by characterizing the operating environment of the oscillator. An electronic device monitors parameters that are determined to have an effect on the frequency accuracy of the internal frequency source. Temperature is one parameter known to have an effect on the frequency of the internal frequency source and a primary contributor to device temperature is the RF Power Amplifier (PA). The electronic device collects and stores the activity level of the PA. The effective PA duty cycle over a predetermined period of time is calculated. The LO operating environment is stabilized by operating the PA at the calculated duty cycle when the LO is required to operate in a high stability mode.

Method and apparatus for compensating local oscillator frequency error through environmental control

The frequency error of an oscillator is minimized by characterizing the oscillator. A reference signal from an external source containing a minimal frequency error is provided to an electronic device. The external signal is used as a reference frequency to estimate the frequency error of an internal frequency source. The electronic device monitors parameters that are determined to have an effect on the frequency accuracy of the internal frequency source. Temperature is one parameter known to have an effect on the frequency of the internal frequency source. The electronic device collects and stores the values of the parameters as well as the corresponding output frequency or frequency error of the internal frequency source. The resultant characterization of the internal frequency source is used to compensate the internal frequency source when the internal frequency source is not provided the external reference signal.

Method and apparatus for compensating local oscillator frequency error

A clock circuit generates a reference clock signal based on a resonant frequency of a crystal, generates thermometer-coded signals based on the reference clock signal, and generates a pulse train based on the thermometer-coded signals. The pulse train has a frequency that is a multiple of the frequency of the reference clock signal. Additionally, the clock circuit includes a phase-lock loop for generating an output clock signal based on the pulse train and aligning a phase of the output clock signal with pulses in the pulse train. In various embodiments, the frequency of the reference clock signal is the same as the resonant frequency of the crystal and the frequency of the output clock signal is a multiple of the resonant frequency of the crystal. Moreover, reference clock signal and the output clock signal each have a long-term jitter based on the precision of the resonant frequency of the crystal.

Clock circuit for reducing long term jitter

A voltage controlled oscillator includes an active element having a first connection point for connection to a voltage source and an output connection point. A tunable resonator including a first voltage tunable dielectric device is connected to an input of the active element. A first circuit branch is also connected to the active element. The first circuit branch can include a second voltage tunable dielectric device. A tuning voltage controller supplies a control voltage to the first and second voltage tunable dielectric devices to control the frequency of an oscillating voltage at the output connection point. In a reflect type voltage controlled oscillator, the first circuit branch is a bypass circuit. In a transmission type voltage controlled oscillator, the first circuit branch includes a phase shifter and is connected between the active element output connection point and the tunable resonator.

Voltage controlled oscillators including tunable dielectric devices

Stereo recovery circuitry for a digital receiver is disclosed that provides increased accuracy and efficiency in recovering stereo signal information from transmitted stereo signals The stereo decoder includes a digitally controlled oscillator that recovers a pilot tone signal from transmitted stereo signal information By processing demodulated stereo signals on the digital side and digitally controlling the oscillator, the stereo decoder has increased efficiency and accuracy In one embodiment, the oscillator may be a phase-locked-loop having a loop filter and an amplitude stabilized tunable resonator Additional circuitry is disclosed for utilizing the pilot tone signal to recover left and right channel signal information from the demodulated stereo signals

Digital stereo recovery circuitry and method for radio receivers

There is described a stabilization process for the local oscillator frequency in wide-band tunable DROs employed in receivers of a digital microwave radio link. A microprocessor, already provided for normal operation control, cyclically reads the control voltage of a VCO inserted in a PLL which reconstructs an intermediate frequency carrier used to coherently demodulate the received signal. The voltage read is compared with an optimal reference value by taking an error signal which controls a varicap diode of the DRO for tuning correction. With each reading, the optimal value can be modified on the basis of temperature data supplied by a heat sensor to cancel the effect of temperature on the reference.

Automatic local oscillator frequency stabilization process in radio receivers employing a wide-band tunable local dielectric-resonator oscillator and associated device

De Marzi Giuseppe

Papers

Automatic local oscillator frequency stabilization process in radio receivers employing a wide-band tunable local dielectric-resonator oscillator and associated device