Pacific Communication Sciences, Inc.

Rockwell Semiconductor Systems, Inc.

Titan Linkabit Corporation

Bjorn E Bjerede

Joseph T Lipowski

James E Petranovich

Benny Madsen

Sheldon L Gilbert

F Matthew Rhodes

John Francis O'Connor

Methods and apparatus for digital cordless telephone systems are preferably implemented in an integrated circuit chip set having one or more chips, adapted to receive a voice signal, for converting the voice signal into a digital signal of a desired form, for converting the digital signal into an analog signal and for modifying the frequency of the analog signal, for up converting during transmission the frequency of the analog signal from an intermediate frequency to a desired radio frequency and for down converting during reception from a selected radio frequency to the intermediate frequency and for amplifying the radio frequency signal during transmission and for switching the antenna between the transmit and receive paths. It is preferred for the chip set to include a base chip, an intermediate frequency chip, a radio frequency chip and an amplifier chip. It is preferred to also provide a synthesizer integrated circuit chip for generating carrier select signals to be used by the radio frequency chip in selecting desired carrier frequencies. The invention also includes a frequency translation scheme to be utilized in conjunction with the various chips. Utilization of this scheme serves to reduce spurious noise as well as to suppress transmit signals during receive operations. The invention also includes various sensors for adjusting the level of the signal to be transmitted and for adjusting the level of the signal received at the antenna.

Method and apparatus of frequency generation for use with digital

An integrated circuit chip set is provided for use in a radio communication system in which a modulated digital input signal is processed for transmission and a modulated signal received from an antenna is processed to provide an output signal, wherein the modulation of the signals is either QPSK or FSK and the signal transmission and reception is by either TDD or FDD. The chip set includes an IF integrated circuit chip for processing a digital input signal to convert the digital input signal into an analog input signal and to provide the input signal at an intermediate frequency and for processing a received signal at the intermediate frequency to down convert the frequency thereof and to provide an output signal from the down-converted received signal; and an RF integrated circuit chip for processing the input signal provided by the IF chip at the intermediate frequency to up convert the frequency thereof to a transmission frequency and for processing a received signal provided at the reception frequency to down convert the frequency thereof to the intermediate frequency. The IF chip includes switches and terminals for enabling the IF chip to be connected for processing by the IF chip of QPSK-modulated signals or to be connected for processing by the IF chip of FSK-modulated signals; and the RF chip includes terminals for enabling the RF chip to be connected for processing by the RF chip of TDD transmitted and received signals or to be connected for processing by the RF chip of FDD transmitted and received signals.

Universal radio architecture for low-tier personal communication system

Methods and apparatus for frequency synthesization are shown for generating an output signal of desired frequency. The frequency synthesizer includes an oscillator for generating an output signal at the desired frequency in response to a control signal. A first detector compares the output signal to a reference signal and generates a first difference signal representative of the differences, preferably in phase and frequency, between the output and the reference signals. A second detector compares the output signal to the reference signal and generates a second difference signal. A controller generates the control signal in response to either the first or second difference signal. A selector member selects between the first and second detectors to provide either the first or second control signal to the controller in response to a selection signal. A lock detector detects when the output signal and said reference signal are in a predetermined relation and generates the switch signal in response to the detection of the occurrence of such predetermined relation.

Method and apparatus for frequency synthesization in digital cordless

A direct digital frequency synthesizer generates an analog waveform of a predetermined frequency from accumulated digital frequency words which, as accumulated, represent the phase of a sine wave of the predetermined frequency. The synthesizer includes a phase accumulator, a 4-bit non-linear digital-to-analog converter (DAC) and a sample and hold circuit. The phase accumulator includes a 4-bit coarse-component accumulator for accumulating coarse phase components of the digital frequency words and a fine-component accumulator for accumulating fine phase components of the digital frequency words. The phase accumulator increments the coarse-component accumulator in response to the accumulated fine phase components exceeding a predetermined value. The 4-bit non-linear DAC converts the four bits accumulated in the coarse-component accumulator into an analog waveform of the predetermined frequency. The phase accumulator suppresses the generation of spurious frequency components in the analog waveform by randomly dithering the rate at which the coarse component accumulator is incremented by the phase accumulator. The sample and hold circuit is coupled to the output of the nonlinear DAC for mitigating any glitch errors induced in the nonlinear DAC by sampling the analog waveform at such times as when glitch-induced errors are not present.

Growing community of inventors

La Jolla, CA, United States of America

Bjorn E Bjerede