Abstract: A frequency demodulator comprises a frequency discriminator configured to generate a frequency modulation signal from frequency modulated signal, circuitry for generating a phase modulation signal from the frequency modulation signal, and a click reduction signal processing (CRSP) circuit operable to remove noise enhancements from the phase modulation signal caused by clicks. By first converting the frequency modulation signal to a phase modulation signal, noise enhancements caused by clicks are more readily distinguished from other noise in the phase modulation signal. After the noise enhancements have been removed by the CRSP, the frequency modulation is recovered substantially free of clicks. Removal of the clicks results in an improved output signal-to-noise ratio, thereby advantageously extending the onset of the threshold effect.

Abstract: The present invention, generally speaking, uses multiple selectable power supply paths, a saturation detector, or combinations of the same to achieve efficient power supply processing. In one aspect of the invention, a power supply processing circuit includes a first switched converter stage and a second linear stage. Depending on the power supply desired, the first stage may be bypassed to avoid conversion losses. In another aspect of the invention, a saturation detector is used to control the first stage such that the second stage operates efficiently just short of saturation, thereby avoiding distortion.

Abstract: A multiple path angle modulator includes a closed secondary loop added to a main control loop to automatically adjust a scaling factor related to high frequency gain. The main control loop is configured as a primary path to process the low frequency portion of the angle modulation signal, and the secondary loop is configured as an auxiliary path to process the high frequency portions of the angle modulation signal. The secondary loop senses calibration information and uses it to continuously calibrate the gain within the modulation loop in real time while the system performs its primary operation, thereby eliminating the need for a system shut down or calibration specific timing, such as a lapse time, to balance the modulation paths. Calibration is continuously performed as a background process. The angle modulator is applicable to all modulation type systems.

Abstract: The present invention, takes advantage of the properties of quadrature signals to achieve precise quadrature alignment in a simple fashion. The expectation of the product of quadrature signals is zero. A phase error detection network therefore operates by multiplying the received quadrature signals and low-pass filtering the product to produce an error signal. When the signals are in precise quadrature relationship, the error signal will be zero. Real-time feedback control may be used to drive the error to zero. In accordance with another aspect of the invention, a variable phase shift network is achieved using a dual delay line. The difference in delay between the two delay lines is adjusted in response to the error signal to obtain precise quadrature alignment. The principles of the invention may be applied in connection with traditional mixer architectures or with switch-mode architectures.

Abstract: A phased array receiver includes a plurality of receive paths having a plurality of downconverters, a plurality of digitally controlled local oscillators associated with the plurality of receive paths, and a combiner. In response to a plurality of digital phase control signals, the plurality of digitally controlled local oscillators controls phases of a plurality of local oscillator signals generated by the plurality of digitally controlled local oscillators. The phases of the plurality of local oscillator signals are introduced as phase shifts in a plurality of intermediate frequency signals produced by the plurality of downconverters. The plurality of digitally controlled local oscillators is configured to respond to changes in digital values of the plurality of digital phase control signals to achieve a desired phase relationship among the phases of the intermediate frequency signals.

Abstract: A modulator includes a power driver, a power amplifier, and a heterojunction bipolar transistor (HBT) type device. The power driver is for receiving an amplitude modulation signal and for providing a control signal. The power amplifier is for receiving a phase modulation signal, a bias voltage, and the control signal. The power amplifier is for providing a radio frequency signal as an output based on the phase modulation signal, the bias voltage, and the control signal. The switching device is for coupling the power driver to the power amplifier such that the control signal is provided to the power amplifier in a timely manner.

Abstract: A multiple carrier radio system includes a baseband subsystem and a plurality of polar modulators. The polar modulators are mounted at antenna locations (e.g., in a base transceiver station (BTS)) above the ground), and are configured to receive modulation signals generated by the baseband subsystem. The plurality of polar modulators generates a plurality of modulated RF carrier signals using the modulation signals. The modulated RF carrier signals are radiated by a corresponding plurality of antenna elements coupled to the plurality of polar modulators.

Abstract: A radio system includes a baseband integrated circuit and a radio frequency module partitioned along an analog-digital boundary. The baseband integrated circuit is configured to generate modulation signals from a digital message. The radio frequency module includes a controlled oscillator, a radio frequency upconverter and a power amplifier. The controlled oscillator is configured to generate a radio frequency transmit carrier signal. The radio frequency upconverter is configured to generate radio frequency modulated signals from the radio frequency transmit carrier signal and information contained in the modulation signals received from the baseband integrated circuit. Finally, the power amplifier is configured to amplify the radio frequency modulated signals so that the resulting amplified radio frequency modulated signals are suitable for being radiated over the air to a remote receiver.

Abstract: An apparatus for providing an angle modulated signal includes a tunable oscillator circuit, a variable time delay circuit, and an optional scaling and delay control apparatus. The tunable oscillator circuit generates an oscillatory signal having a predetermined frequency. The variable time delay circuit operates to delay the oscillatory signal in accordance with time varying changes in an angle control signal, thereby producing the desired angle modulated signal. The scaling and delay control apparatus is configured to scale the angle control signal to account for frequency dependent phase delays of the oscillatory signal through the variable time delay circuit.

Abstract: Methods and systems for recovering clock and data in data streams communicated over serial communications links. An exemplary serial communications receiver system includes a line receiver configured to receive a data stream from a serial communications link and an instant-acquisition clock and data recovery circuit coupled to the line receiver. The instant-acquisition clock and data recovery circuit includes a time interval detector and a sampling clock selector. The time interval detector is operable to sample the data stream received by the line receiver according to a multi-phase set of sampling clocks. The sampling clock selector is operable to designate one of the sampling clocks of the multi-phase set of sampling clocks as a recovered clock, based on a data transition in the received data stream detected by the time interval detector.

Abstract: The present invention, generally speaking, uses multiple selectable power supply paths, a saturation detector, or combinations of the same to achieve efficient power supply processing. In one aspect of the invention, a power supply processing circuit includes a first switched converter stage and a second linear stage. Depending on the power supply desired, the first stage may be bypassed to avoid conversion losses. In another aspect of the invention, a saturation detector is used to control the first stage such that the second stage operates efficiently just short of saturation, thereby avoiding distortion.

Abstract: A hybrid modulator apparatus includes a modulator that amplitude modulates a power supply signal. A correction circuit coupled in parallel with the modulator reduces errors caused by the modulator. In one embodiment the modulator includes a digital pulse-width modulator (PWM) and a buck converter. The K most significant bits (MSBs) of N-bit input digital words are used by the digital PWM and a buck converter to generate an amplitude modulated power supply signal having a plurality of quantized voltage levels. The remaining N?K bits of each N-bit words may be used to dither the input drive to the PMW, to produce an error signal at the output of the modulator representing quantization errors caused by only applying the K MSBs to the PWM. The correction circuit compares the error signal to a signal formed form all N bits of the N-bit words in reducing the quantization errors.

Abstract: The present invention, generally speaking, takes advantage of the properties of quadrature signals to achieve precise quadrature alignment in a simple fashion. In particular, the expectation of the product of quadrature signals is zero. In accordance with the teachings of the invention, a phase error detection network therefore operates by multiplying the received quadrature signals and low-pass filtering the product to produce an error signal. When the signals are in precise quadrature relationship, the error signal will be zero. Real-time feedback control may be used to drive the error to zero. In accordance with another aspect of the invention, a variable phase shift network is achieved using a dual delay line. The difference in delay between the two delay lines is adjusted in response to the error signal to obtain precise quadrature alignment. The principles of the invention may be applied in connection with traditional mixer architectures or with switch-mode (e.g., “aliased undersampling”) architectures.

Abstract: Methods and apparatus for controlling power in a polar modulation transmitter. An exemplary polar modulation transmitter includes a radio frequency power amplifier (RF PA), a phase path having circuitry operable to generate a constant amplitude phase modulated signal, and an amplitude path including an envelope modulator circuit having first and second envelope modulation paths. The RF phase modulated signal is applied to an RF input of the RF PA, while an envelope modulated power supply signal generated by a selected one of the first and second envelope modulation paths is coupled to a power supply input of the RF PA. The second envelope modulation path is selected during times when the power required by the RF PA is below some predetermined power level. During times when the RF PA requires power above the predetermined power level, the first envelope modulation path is selected.

Abstract: A polar-based modulator includes an amplitude signal generator operating at a set gain and a command module that selects an appropriate one parameter lookup table based on an identification of the current network communication system. The command module receives a digital representation of the desired amplitude and using the received digital amplitude and selected parameter lookup table determines control commands used by a scalar to appropriately modulate an amplitude modulated signal output from the amplitude signal generator. Use of the parameter lookup table and command module in the digital realm eliminates the complexities of comparable functionality in the analog realm. Further, operating the amplitude signal generator at a set gain and scaling the output eliminates the complexities associated with generating an appropriately amplified signal within the amplitude signal generator and improves the overall efficiency for generating such an amplitude modulated signal.

Abstract: Methods and apparatus for reducing radiated field feedback in radio frequency (RF) transmitters. An exemplary RF transmitter includes a power amplifier (PA) and a low-field oscillator (LFO) that are co-located, either on a common module or integrated in the same integrated circuit chip. By using an LFO for the transmitter's local oscillator, radiated field feedback from the PA to the LFO is substantially reduced. In addition to, or instead of using an LFO to reduce radiated field feedback, the LFO or a voltage controlled oscillator (VCO) may be configured to operate at either a harmonic or a non-integer multiple of the transmitter's output signal frequency.

Abstract: The present invention, generally speaking, provides methods and apparatus for producing an amplitude modulated communications signal, in which a constant-envelope carrier signal is modified in response to a power control signal to produce a modified constant-envelope carrier signal. The modified constant-envelope carrier signal is amplified in response to an amplitude modulation signal to produce a communications signal having amplitude modulation and having an average output power proportional to a signal level of the modified constant-envelope carrier signal. This manner of operation allows wide dynamic range of average output power to be achieved. Because amplitude modulation is applied after amplitude varying circuitry used to produce the modified constant-envelope carrier signal, the amplitude modulation is unaffected by possible non-linearities of such circuitry.

Abstract: A radio frequency power amplifier (RF PA) apparatus includes an RF PA and a waveform converter. The waveform converter is configured to receive a sinusoidal RF signal and generate a nonsinusoidal RF signal, which is used to drive an active device (e.g., a field effect transistor (FET) or bipolar junction transistor (BJT)) of the RF PA. The nonsinusoidal RF signal, which may comprise a square wave or a substantially-square wave signal, has signal characteristics that result in less leakage through the active device's input-output parasitic capacitance, compared to the leakage that would result if the sinusoidal RF signal was used to drive the active device. The leakage control methods and apparatus of the present invention may be advantageously employed in a variety of applications including, for example, RF polar transmitters.

Abstract: A power amplifier of a polar transmitter having separate amplitude and phase paths is configured so that its output power is controlled by power control circuitry disposed in both the amplitude and phase paths of the transmitter. Coarse power control is provided by coarse power control circuitry configured in the phase path. Fine power control is performed by digital power control circuitry configured in the amplitude path. The combined coarse power control circuitry in the phase path and digital power control circuitry in the amplitude path allows the output power of the power amplifier to be controlled at the accuracy and resolution required by wireless communications standards such as, for example, the W-CDMA standard.

Abstract: The present invention, generally speaking, provides a time shift angle demodulator that is of simple construction and has an extended linear range. Range extension is achieved by using the input signals directly, not simply post-processing the S-PFD outputs. In accordance with one embodiment of the invention, a method of measuring the phase or frequency of a periodic input signal uses a periodic reference signal and includes comparing the input signal to the reference signal to obtain a lead signal and a lag signal; changing the count of an up/down counter in dependence on the input signal, the reference signal, the lead signal and the lag signal; and using the lead signal, the lag signal and the count signal to produce a phase or frequency signal.