Abstract: Disclosed is an oscillator circuit (10) for use in a local oscillator of an RF communications device (100) that communicates over an RF channel. The oscillator circuit includes an oscillator transistor coupled to a power supply voltage (Vcc) through a buffer transistor, and a biasing network having bias voltage outputs coupled to a control input of the oscillator transistor and to a control input of the buffer transistor. In one embodiment the bias voltage network is coupled to Vcc, while in another embodiment the bias voltage network is coupled to a separate voltage (Vbias). Circuitry is provided for setting a magnitude of Vcc and/or Vbias as a function of at least one of RF channel conditions, such as channels conditions determined from a calculation of the (SNR), or an operational mode of the RF communications device. The magnitude of Vcc (and Vbias) may be set between about zero volts (i.e., turned off) and some maximum value.

Abstract: Systems and methods are provided for providing high dynamic range operation over a variable range of frequencies. A delta-sigma modulator, having associated frequency characteristics, produces a digital output signal. A digital-to-analog converter converts the digital output signal into an analog signal. A clock circuit provides a clock signal to the delta-sigma modulator and the digital-to-analog converter. A frequency control controls one or more of the clock circuit, the delta-sigma modulator, and the digital-to-analog converter to alter the frequency characteristics of the delta-sigma modulator. A filter circuit can provide one or more passbands to one or more downstream amplifiers ensuring that out of band quantization noise is removed before amplification.

Abstract: A local oscillator (LO) circuit is disclosed which provides improved isolation between the unselected LO source and a mixer. The LO circuit includes a first LO source to generate a first periodic signal cycling at a first frequency, a second LO source to generate a second periodic signal cycling at a second frequency different than the first frequency, a limiter, a first switching element to selectively couple the first LO source to the limiter, and a second switching element to selectively couple the second LO source to the limiter. The limiter improves the isolation of the leakage LO signal (i.e. the unselected LO signal) with respect to the selected LO signal. The improved isolation comes about because the limiter gain associated with the selected LO signal is greater than the gain associated with the leakage LO signal. A receiver and transmitter using the LO circuit are also disclosed.

Abstract: This disclosure presents a communication receiver system for spacecraft that includes an open loop receiver adapted to receive a communication signal. An ultrastable oscillator (USO) and a tone detector are connected to the open loop receiver. The open loop receiver translates the communication signal to an intermediate frequency signal using a highly stable reference frequency from the USO. The tone detector extracts commands from the communication signal by evaluating the difference between tones of the communication signal.

Abstract: A transceiver for a code division multiple access communication system comprises a receiver to receive coded information signals and a transmitter to transmit coded information signals. A local oscillator provides a time and frequency reference for the receiver and the transmitter. A timing controller provides timing signals for the receiver and the transmitter. A signal processor decodes received signals to determine a common error associated with the timing controller. A timing correction circuit smoothly adjusts the timing of the coded information signals transmitted by the transmitter responsive to the timing error to reduce the timing error over a desired time interval.

Abstract: A receiver and a composite component for preventing noise produced by sneaking of a local oscillation signal. An FM receiver comprises a high-frequency amplifier circuit 11, a mixing circuit 12, a local oscillator 13, intermediate-frequency filters 14 and 16, an intermediate-frequency amplifier circuit 15, a limit circuit 17, an FM detection circuit 18, and a stereo demodulation circuit 19. The mixing circuit 12 and the local oscillator 13 constitute a one-chip composite component 30 integrally formed on a semiconductor substrate. The frequency of the local oscillation signal is set so that the difference of frequency between the local oscillation signal and a modulated wave signal may be smaller than the occupied bandwidth of the modulated wave signal.

Abstract: In an exemplary application, an apparatus according to a disclosed embodiment receives a radio frequency signal and outputs an intermediate frequency signal. Rejection of image components in the intermediate frequency signal is obtained without the need to preprocess the radio frequency signal with an image reject filter. Such an apparatus may also exhibit an image rejection performance that is robust to frequency deviation of a local oscillator.

Abstract: An offset history table is implemented and maintained in a BLUETOOTH device and is used to pre-seed an expected frequency offset of a received signal from another BLUETOOTH device. The disclosed offset history table includes one entry for each piconet device in a particular piconet, each entry including a best guess of the relevant piconet device's frequency offset with respect to the receiving BLUETOOTH device. Using a frequency offset history table and a pre-seeded frequency offset corresponding to an expected frequency offset based on the offset value maintained in the frequency offset history table, the performance of a BLUETOOTH device can be increased in a steady state piconet scenario.

Abstract: A local oscillator provides an in-phase local oscillating signal and quadrature-phase signal to first and second mixers outputting an input signal with a mixed in-phase local oscillating signal and quadrature-phase local oscillating signal, respectively. The oscillator comprises a local oscillator having first and second delay cells and outputting said in-phase local oscillating signal and said quadrature-phase local oscillating signal; and a correction circuit for controlling phase matching characteristics, said correction circuit setting bias current flowing in said first and second delay cells of said local oscillator as being to be different. In another embodiment, the phase matching characteristic is controlled by setting the bias voltage applied to the first and second delay cells as being to be different, by setting the width of the active device included in the first and second delay cells dells as being to be different, or by setting impedance of passive device to be different.

Abstract: An RF power oscillator for contactless card antennas shapes a carrier signal at the operating frequency utilizing a delay circuit having a number of taps for delaying the carrier signal by different lengths of time. The delayed signals are input into a buffer and output through impedance elements to a node coupled to the antenna. The resulting waveform for a square wave input signal, and equal-length delay taps, is a trapezoidal wave output. Any input wave form can be shaped in a variety of ways depending upon the combinations of delay taps used. Since the buffer drivers for each delayed wave switch state at slightly different times, the amplitude and bandwidth of emitted electromagnetic interference (EMI) is reduced for the transmission circuit.

Abstract: Methods to generate a mobile time reference are provided. A representative method includes providing a high frequency clock, providing a low frequency clock, generating a mobile time reference using the high frequency clock, maintaining the mobile time reference using the low frequency clock when the high frequency clock is turned off, and continuing to generate the mobile time reference using the high frequency clock when the high frequency clock has been turned back on. Systems and other methods are also provided.

Abstract: A receiver, in particular for mobile radio, includes a receiver branch with a mixer, downstream of an analog/digital converter. A reference generator generates a reference clock, which is fed to the converters or PLL synthesizers of the mixer by integral multiplication or division. As a result, a particularly energy-saving and space-saving circuit configuration is realized, which has a low level of mutual interference between the signals and is suitable (in particular for Universal Mobile Telecommunication System, UMTS). In a preferred embodiment, the receiver is developed into a transceiver by providing a transmission path.

Abstract: A receiver for use in a wireless communication system includes a voltage controlled oscillator and estimating means for obtaining a frequency estimate to adjust the voltage controlled oscillator, thereby correcting an oscillator frequency error. The estimating means performs a number of block correlations on a received signal with a known midamble reference. The output of the block correlators are conjugately multiplied and summed to produce a low-variance estimate of the phase change between correlators. A number of the largest summed values are located, and the located values that exceed a detection threshold are summed to provide a single complex number whose angle is an estimate of the phase change between the correlators.

Abstract: A semiconductor integrated circuit device for communication is provided with a PLL circuit or the like formed therein, the PLL circuit which is capable of realizing the compensation of fluctuation due to temperature change, the inhibition of increase in the chip area and the ensurement of the performance margin, and which controls a VCO having multiple oscillation frequency bands. In the case where automatic calibration is performed by switching a switch to a side of a DC voltage source in the PLL circuit using a VCO having multiple oscillation bands, a tuning voltage (Vtune) of an RFVCO is fixed to a voltage value of a DC voltage source. However, since a temperature characteristic of canceling a VCO oscillation frequency is given to the DC voltage source, it is possible to minimize the influence on the band selection when a calibration table comes to no optimum one.

Abstract: A power supply circuit of a low noise block converter (LNB) includes a plurality of output voltage regulators. A first output voltage regulator, a local oscillator circuit, a second output voltage regulator, and an LNA are connected in series in a direction in which a power supply current flows. Therefore, a voltage adjustment width of the output voltage regulator can be reduced and a power loss can be reduced. A value of current flowing in the power supply circuit can also be decreased. Accordingly, an LNB with a reduced power consumption can be realized.

Abstract: An analog open-loop voltage controlled oscillator (VCO) calibration circuit and method for selecting the frequency of the VCO for a phase locked loop (PLL). A frequency divider module produces a 50% duty cycle divided local oscillation and a 50% duty cycle divided reference signal, wherein the divided signals are substantially equal. A period-to-voltage conversion module converts the divided local oscillation signal and the divided reference signal to voltages proportional to the divided signals. A comparator module produces a frequency adjustment signal based on a comparison of the proportional voltages and couples the frequency adjustment signal to a logic module which produces a frequency compensation signal based on the frequency adjustment signal. The frequency compensation signal functions to adjust the configuration of switched capacitors in a capacitor bank, coupled to the VCO tuned circuit, until the divided local oscillation signal is substantially equal to the divided reference signal.

Abstract: A carrier recovery method and apparatus using multiple stages of carrier frequency recovery are disclosed. A receiver uses multiple frequency generation sources to generate carrier signals used to downconvert a received signal. An analog frequency reference having a wide frequency range and coarse frequency resolution is used in conjunction with a digital frequency reference having a narrow frequency range and fine frequency resolution. The multiple carrier signals are multiplied by a received signal to effect a multi-stage downconversion, resulting in a baseband signal. A frequency tracking module measures the residual frequency error present in the baseband signal. The measured residual frequency error is then used to adjust the frequencies of the carrier signals generated by the multiple frequency generation sources.

Abstract: A mobile station is disclosed for performing an automatic frequency control based on a correspondence of a frequency error and TCXO control voltage to a base station. A plurality of frequency error measuring units each measure a frequency error between an internal clock signal and a clock signal in a specified base station. A plurality of control voltage calculators, each associated with a corresponding one of the plurality of frequency error measuring units, integrate a frequency error measured by the corresponding frequency error measuring unit to produce a control voltage. A control voltage selector selects a control voltage corresponding to a base station currently in communication with the mobile station from among control voltages calculated by the plurality of control voltage calculators. A clock signal generator generates an internal clock signal at a frequency in accordance with the selected control voltage.

Abstract: A system, apparatus and corresponding method by which to synchronize to a time reference a main module of a device—a main module such as global positioning system (GPS) receiver—using a cellular communication signal received by a cellular module also included in the device. To synchronize the main module to the reference time, the invention provides a method including the steps of: having the cellular module respond to the cellular communication signal by providing to a clock module of the main module a trigger pulse derived from the data component of the cellular communication signal, and also by providing to the main module information relating the trigger pulse to a universal time. The main module is then able to resolve a value for time based on the information relating the trigger pulse to a universal time and the trigger pulse.

Abstract: A mobile communications device using a common oscillator for communication and global positioning system (GPS) functions. In one embodiment, a communications unit receives a precision carrier frequency signal from a source and generates a reference signal that is used to calibrate a common oscillator.

Abstract: An amplitude modulation receiver including an antenna for receiving a signal and an input filter connected to the antenna. A variable gain amplifier is connected to the input filter and is responsive to a gain control signal. An A/D converter is connected to the variable gain amplifier and is responsive to a sampling signal and provides a sampled digital signal. A D/A converter receives a demodulated signal and provides an analog output signal. A controller receives and demodulates the sampled digital signal from the A/D converter, generates the gain control signal for the variable gain amplifier, generates the sampling signal for the A/D converter, and provides the demodulated signal to the D/A converter. The demodulation and generation of the gain control signal and the sampling signal are performed in software.

Abstract: Only a single, standard-independent clock rate is generated in a signal processor or a signal processing structure, and correspondingly only precisely one clock frequency generator is then arranged on the chip. The signal processing path includes at least one controllable, asynchronous decimator for transposing the reception signals present in a uniform time frame into a respective standard-specific time frame. This enables signals of a variety of mobile phone standards to be processed.

Abstract: The present invention is related to a method and apparatus for automatic frequency correction of a local oscillator. The apparatus receives a carrier signal. The carrier signal includes a code sequence known to the apparatus. The apparatus downconverts the carrier signal to a baseband signal using the local oscillator. The apparatus performs a block correlation of the samples of the baseband signal with the known code sequence to generate a frequency error signal. The frequency error signal is fed back to the local oscillator to correct the frequency error.

Abstract: For use in an orthogonal frequency division multiplexing (OFDM) transceiver, a multimode local oscillator circuit and a method of operating the same. In one embodiment, the circuit includes: (1) a single sideband mixer having an output, first and second inputs and a local oscillator input and (2) a signal generator, coupled to the single sideband mixer, for alternatively providing to the first and second inputs: (2a) constant values to cause the single sideband mixer to generate a first receiver local oscillator signal for operating the OFDM transceiver as a zero intermediate frequency receiver and (2b) a first orthogonal baseband signal to cause the single sideband mixer to generate a second receiver local oscillator signal for operating the OFDM transceiver as a low intermediate frequency receiver.

Abstract: DC offset is estimated in a wireless receiver during a period when receive energy is blocked from reaching a mixer within the receiver. The estimated DC offset value may then be used to reduce DC offset within the wireless receiver when a receive signal is subsequently being processed.

Abstract: This patent describes a method and system which overcomes the LO-leakage problem of direct conversion and similar RF transmitters and receivers. To solve this problem a virtual LO™ signal is generated which emulates mixing with a local oscillator (LO) signal. However, the virtual local oscillator (VLO) signal is constructed using signals that do not contain a significant amount of power (or no power at all) at the wanted output RF frequency, so there is no LO component to leak to the output. The invention also does not require sophisticated filters or large capacitors as other designs in the art, so it is fully integratable.

Abstract: A portable radio terminal for realizing automatic frequency control (AFC) for automatically controlling the oscillation frequency of an oscillator includes a unit for intermittently performing AFC operation, and a unit for shortening an AFC operation stop period when the frequency shift of the oscillation frequency is large. An AFC control method is also disclosed.

Abstract: A modulator generates a combined signal consisting of audio and video signals and converts the combined signal to one of a plurality of frequencies in dependence upon a desired output frequency and broadcast standard. The modulator includes a summing amplifier, a first frequency synthesizer and a second frequency synthesizer. The summing amplifier has a first input for receiving a video signal, a second input for receiving a first audio signal, a third input for receiving a second audio signal, and an output for outputting a modulated summed signal. The first frequency synthesizer generates a first frequency for mixing with the modulated summed signal to generate a high intermediate frequency (HI-IF) signal. The second frequency synthesizer generates a second frequency for mixing with said HI-IF signal to generate a desired RF output signal.

Abstract: A frequency synthesizer usable in a wireless communication device is disclosed that may ensure a low phase noise and an improved performance. The frequency synthesizer has a phase locked loop comprising a controllable oscillator generating an output signal with an output frequency that can be adjusted within a predefined frequency range dependent on the value of a first control signal. A phase/frequency detector generates an error signal in response to a phase and/or frequency difference between an input signal generated by frequency dividing said output signal, and a reference signal. A loop filter generates the first control signal based on said error signal and outputs same to the controllable oscillator. A control unit generates a second control signal from the loop filter signal and provides the second control signal to the controllable oscillator, which is arranged for modifying the predefined frequency range based on the second control signal.

Abstract: In a mobile communication device, communication can be resumed upon next communication without causing problem even when an AFC control signal becomes abnormal upon interruption of communication. Locked state and unlocked state of an AFC portion is monitored by an AFC monitoring portion 5. Upon interruption of communication, if in unlocked state, a TCXO 1 is controlled by the AFC portion using a TCXO control signal upon preceding locked state. By this, when communication failure is caused by influence of building, tunnel or the like or when communication is terminated, a reference frequency of the mobile communication device does not significantly offset from the reference frequency of a base station to facilitate communication upon next communication.

Abstract: A vehicular electronic apparatus contains a microcomputer, and a crystal oscillator for determining an operating frequency for the microcomputer. An oscillation frequency of the crystal oscillator is selected such that a frequency difference between a frequency of a broadcast wave received by a vehicular receiver and an oscillation frequency of the crystal oscillator or a higher harmonic of the oscillation frequency is 15 kHz or higher or 400 Hz or lower, to suppress an interference in receiving the broadcast wave.

Abstract: A method and apparatus for compensating an oscillator in a location-enabled wireless device is described. In an example, a mobile device includes a wireless receiver for receiving wireless signals and a GPS receiver for receiving GPS signals. The mobile device also includes an oscillator having an associated temperature model. A frequency error is derived from a wireless signal. The temperature model is adjusted in response to the frequency error and a temperature proximate the oscillator. Frequency error of the oscillator is compensated using the adjusted temperature model. In another example, a frequency error is derived using a second oscillator within the wireless receiver.

Abstract: A phase locked loop (PLL) frequency synthesizer to produce a local oscillator signal for a superheterodyne transmitter for operation at a first and a second RF frequency band that are disparate. The transmitter has a fixed intermediate frequency that is a sizable fraction of the bandwidth of one or more of the RF bands. The superheterodyne transmitter includes a first and a second RF upconverter, each having a local oscillator input coupled to the frequency synthesizer. The synthesizer includes a voltage controlled oscillator (VCO) to provide a VCO frequency signal and a non-integer frequency multiplier to produce a frequency multiplied signal having a frequency wither at the VCO frequency or at a non-integer multiple of the VCO signal depending on a control input.

Abstract: A temperature compensating circuit is provided in a radio unit, an ambient temperature is detected by a temperature sensor of the temperature compensating circuit, the detected temperature value is supplied to a correction address storage section as an address after it is converted to a digital value, and thus a correction address corresponding to a correct temperature value obtained by correcting the detected temperature value is read out. Then, the correction address is supplied to a frequency correction data storage section to read out frequency correction data corresponding to the corrected temperature value, and the frequency correction data is converted to an analog control voltage by a D/A converter and then supplied to a variable capacitance element of a reference oscillator, thereby making it possible to correct the reference oscillation frequency according to the temperature.

Abstract: An oscillator that provides a quadrature output and has a cross-coupled configuration is disclosed. The oscillator generates an output signal having a frequency. Two phase shift circuits, or stages, are activated by a control signal to provide phase shifts within the oscillator. Each phase shift circuit includes poles to provide the phase shift. A pole includes a varactor to tune, adjust or vary the phase shift accordingly.

Abstract: The present invention provides for a system and method for improvement of radio transmitter and receiver frequency accuracy for a local radio communication unit that communicates digital data with a remote communication unit. In the local unit the received radio signal is down-converted, and converted to complex baseband digital samples by an analog-to-digital converter. A downlink digital phase rotator applies a fine frequency shift to the samples in accordance with a receiver frequency offset command. The resultant baseband signal is used by the data demodulator and by a receiver frequency error estimator to obtain receiver frequency errors. A data modulator generates baseband complex samples which are shifted in carrier frequency by an integrated uplink digital phase rotator in accordance with a transmitter frequency offset command. The modulated samples are then converted by a digital-to-analog converter and upconverted in frequency for radio transmission to the remote unit.

Abstract: In an impedance matching circuit for a multi-band radio frequency device, a first radio frequency signal in a first sub-band of a multi-band radio frequency signal is selectively outputted. Further, a second radio frequency signal in a second sub-band of the multi-band radio frequency signal is selectively outputted. Selective outputting is done through partly shared and partly non-shared reactive elements, without the need to switch reactive elements.

Abstract: A tuning arrangement in a radio receiver includes a front-end circuit having a tunable band-pass filter that is capable of tunably selecting channels within at least one frequency band of an RF signal. A noise source coupled to an input of the tunable band-pass filter introduces a wide-band noise signal into the front-end circuit. A signal detector coupled to an output of the front-end circuit measures at least one signal power associated with a filtered noise signal derived from the wide-band noise signal. A tuning controller, coupled to the tunable band-pass filter by a tuning control signal, adjusts the tuning control signal in response to the at least one measured signal power for tuning the tunable band-pass filter to a desired filter response.

Abstract: Apparatus, and an associated method, for facilitating frequency offset estimation between communication stations operable in a communication system. A likelihood polynomial is calculated and provided to a filter. The filter forms a filtered representation of the likelihood polynomial, and the filtered representations are down-sampled by a decimator. A sampled, filtered representation of the likelihood polynomial is thereby obtained. The filtered, sampled representation is applied to a root calculator that calculates the roots of the polynomial, thereafter, to be used to compensate for the frequency offset.

Abstract: A frequency scanning receiver minimizes the time needed for setting the frequency of a phased lock loop of a first local oscillator. The frequency scanning receiver is configured so that when the reference frequency of the PLL of the first local oscillator has been set at a high frequency, and the frequency error is less than the second IF, the frequency error is controlled to be zero by the control circuit switching the frequency of a second local oscillator or third local oscillator to an appropriate frequency using an output of a frequency discriminator.

Abstract: A variable frequency oscillator comprising: an oscillatory circuit for generating a periodic output dependent on the capacitance between a first node and a second node of the circuit, and having a capacitative element connected between the first node and the second node; the capacitative element comprising: a variable capacitance unit, the capacitance of which is variable for varying the frequency of the output and a plurality of finite capacitances each being selectively connectable in parallel with the variable capacitance unit between the first node and the second node to trim the frequency of the output.

Abstract: A tuner comprises a first frequency changer with a mixer and local oscillator. The output of the frequency changer is connected to a first intermediate frequency filter, whose output is connected to a second frequency changer. The output of the frequency changer is connected to the usual second intermediate frequency filter and to an amplitude detector. A reference oscillator is connectable under control of a controller via a multiplexer to the input of the mixer. During an alignment mode of the tuner, the reference signal from the oscillator is supplied to the mixer and the local oscillators and are controlled by the controller to sweep across a frequency range encompassing all possible pass frequencies of the filter. The controller monitors the output of the detector so as to establish the frequency response of the filter. Frequency offsets are then stored in the synthesizers and so as to center each channel during a reception mode on the actual center frequency of the filter.

Abstract: A receiver uses an adaptive algorithm to tune a low-cost crystal oscillator according to a temperature compensation profile so as to produce a precision master reference frequency despite temperature, initial tolerance, and aging effects. An automatic frequency control system also tunes the crystal oscillator. The adaptive algorithm adjusts the temperature compensation profile for the crystal oscillator according to the adjustments made by the automatic frequency control should a received signal's quality factor exceed that associated with the temperature compensation profile.

Abstract: A communication apparatus is provided which employs two oscillators to generate a transmission signal and a reception signal, and prevents harmful spurious components from being produced. As shown in FIGS. 9A and 9B, the oscillation frequency fVCO2 of a VCO 2 is given by fVCO2=N×(2×fDD), where fDD is the difference between the transmit frequency fT and receive frequency fR. A 3/(2×N) frequency multiplier outputs a signal with a frequency 3×fDD, and a divide-by-N circuit (2/(2×N) frequency multiplier) outputs a signal with a frequency 2×fDD. Thus the transmit intermediate frequency fTIF is given by fTIF=3×fDD, and the receive intermediate frequency fRIF is given by fRIF=2×fDD. The oscillation frequency fVCO1 of a VCO 1 is fCH. The transmit frequency fT is given by fT=fCH+fTIF=fCH+3×fDD. The circuit can prevent a transmission spurious problem to its own reception band.

Abstract: 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.

Abstract: A ranging receiver (10) including a cellular module (11), for providing time according to a positioning system to enable synchronizing a wireless system to the positioning system. The ranging receiver (10) includes both the cellular module (11) and a main module (12) that provides ranging receiver functionality. When the cellular module (11) receives a time-stamped frame from the wireless system, it sends a trigger signal over a special hardware path to the main module (12), which then relates the time of trigger receipt to time according to the positioning system by calculating a position-velocity-time (PVT) solution, using a local clock (18) to get the difference in time between receipt of the trigger and the instant to which the PVT solution applies, and then communicates to the cellular module (11) when it received the trigger, according to positioning system time.

Abstract: A receiver (22) includes an IF filter (44) and a nearby process-variant circuit (80) formed on a common semiconductor substrate (24). The actual center frequency of the IF filter (44) is determined by resistors (70, 74) and capacitors (72, 76) exhibiting imprecise values and is unlikely to equal a nominal center frequency. The process-variant circuit (80) includes a test resistor (102) and test capacitor (104) formed using the same resistor-forming and capacitor-forming processes used to form the IF filter resistors (70, 74) and capacitors (72, 76). In response a test signal (88) from the process-variant circuit (80) and a reference signal (84) from a process-invariant circuit (82), a tuning parameter for a tunable local oscillator (90) is determined so that a local oscillation signal (94) will exhibit a frequency which, when mixed with an RF signal (38) yields an IF signal (42) at the actual center frequency of the IF filter (44).

Abstract: A direct conversion receiver apparatus includes a local oscillator to produce a first local oscillation signal and a second oscillation signal. A first modulation circuit modulates the first local oscillation signal, and a second modulation circuit modulates the second local oscillation signal. A RF mixer mixes a received radio frequency signal with the modulated first local oscillation signal, and another RF mixer mixes the received radio frequency signal with the modulated second local oscillation signal. Demodulating circuits translate desired signals of the mixed signal from the RF mixers into band and translate undesired signals of the mixed signal out of band. Filters remove the undesired signals from the demodulated signals.

Abstract: A system, apparatus and corresponding method for providing a frequency reference to a user module, such as a global positioning system (GPS) receiver module. The method includes the steps of: a) having a cellular module respond to a cellular communication signal by providing a trigger pulse derived from the data component of the cellular communication signal; and b) directing the trigger pulse along a special hardware path leading from the cellular module to a user module. The special hardware path conducts the trigger pulse in such a way that the trigger pulse is provided to the user module substantially free of any significant random delays. The user module typically includes a frequency generation module that provides a stable frequency reference based on the trigger pulse.

Abstract: A method and apparatus for generating a self-correcting local oscillation includes processing that begins by generating a synthesized frequency from a reference frequency. The processing then continues by dividing the synthesized frequency by a divider value to produce a divided frequency. The processing continues by generating an auxiliary frequency and mixing the auxiliary frequency with the divided frequency to produce a corrected frequency. The processing then continues by mixing the corrected frequency with the synthesized frequency to produce a local oscillation.