Patent ID: 8643444
Filing Date: 2014-02-04
Classification: G01S,H03L

Abstract:
1. A system, comprising: an uncompensated crystal resonator configured to provide a frequency source to a crystal oscillator; a temperature sensor whose electrical resistance varies as a function of temperature in a manner that is both substantially repeatable and predictable and is configured to measure a current temperature; a crystal oscillator configured to output a reference clock frequency signal for a cellular module and a global positioning system (GPS) module; a programmable cellular radio frequency (RF) phase locked loop configured to receive a reference clock signal of the crystal oscillator within the cellular module and compensate for a calculated frequency error between a cellular received downlink signal and a cellular local oscillator (LO) signal during operation of the cellular module; a programmable cellular baseband digital phase locked loop configured to generate a compensated clock for baseband frequency signaling based on the calculated frequency error; a programmable GPS RF phase locked loop and a programmable GPS baseband numerically controlled oscillator configured to receive the reference clock frequency signal and capable of receiving reference clock frequency error estimate signals corresponding to an estimated frequency error and compensate output signals of the GPS RF phase locked loop and the programmable GPS baseband numerically controlled oscillator in a manner that substantially cancels an effect of the estimated frequency error from the output signals; a temperature sensing circuit configured to output a signal substantially proportional to the current temperature as indicated by the temperature sensor; an analytic temperature sensor model configured to receive an output signal of the temperature sensing circuit and map the output signal of the temperature sensing circuit to a temperature sensor resistance estimate and further translate the temperature sensor resistance estimate to a crystal resonator reference oscillator temperature estimate; an analytic crystal reference oscillator frequency deviation versus temperature model configured to receive the temperature sensor resistance estimate of the analytic temperature sensor model and translate the temperature sensor resistance estimate to a frequency deviation estimate through a one-to-one mapping between the crystal resonator temperature and reference oscillator frequency deviation that is based on a calibrated temperature-to-frequency characteristic curve, wherein the programmable GPS RF phase locked loop, the programmable GPS baseband numerically controlled oscillator, or a combination of both are further configured to receive the frequency deviation estimate and compensate a frequency of the output signals, a phase of the output signals, or a combination of both in a manner that substantially cancels an effect of the estimated frequency error from the output signals of the GPS RF phase locked loop and the programmable GPS baseband numerically controlled oscillator thereby allowing the GPS RF phase locked loop, GPS baseband numerically controlled oscillator, or the combination of both to output frequency signals that are substantially temperature compensated in order to accurately process received satellite GPS signals, wherein the temperature sensing circuit comprises resistor divider circuits, an operational amplifier, feedback resistors, voltage offset resistors, and an analog-to-digital converter (ADC), wherein the resistor divider circuit is further comprised of a temperature sensor resistive element and a plurality of switched sense resistors.