摘要:
A method for tuning a filter is provided. The amplitude of a first signal (I1) is compared with the amplitude of a comparison signal. The first signal is generated with a first filter, which receives a first input signal, and there is a phase difference between the first signal (I1) and the comparison signal. A tuning signal is then generated based on differences between the amplitudes of the first signal (I1) and the comparison signal. The tuning signal compensates for any phase and/or amplitude offset in the first signal (I1).
摘要:
A frequency synthesizer that utilizes locked loop circuitry, for example delay locked loop and/or phase locked loop circuits is provided with a means for minimizing static phase/delay errors. An auto-tuning circuit and technique provide a measurement of static phase error by integrating the static phase error in the DLL/PLL circuit. A correction value is determined and applied as a current at the charge pump or as a time/phase offset at the phase detector to minimize static phase error. During normal operation the DLL/PLL is operated with the correction value resulting in substantially reduced spur levels and/or improved settling time.
摘要:
A signal generation power management control system (100) for use in a portable communications device includes a digital signal processor (DSP) (101) for processing a digital source input and providing a digital processed bit stream A digital-to-analog converter (DAC) (103) is used for converting the digital processed bit stream to provide an analog signal. A power management controller (115) within the DSP (101) is then used for interpreting control parameters of signal processing components used within the portable communications device and dynamically adjusting the bias current of these components based on minimal signal requirements of the analog signal.
摘要:
A DC offset correction method and apparatus. Several DC offset correction schemes including a digital binary search scheme (100), a digital slow averaging scheme (200) and an analog integration (50) scheme are provided. A controller (160) selects one or more of the correction schemes in accordance with the desired characteristics provided by each scheme.
摘要:
An oscillator circuit (100) provides improved noise immunity by utilizing a differential common base configuration. The oscillator includes a differential transistor pair (102, 104) having common bases (110) coupled through an AC ground (108) and emitters coupled through a differential common mode point (120). First and second resonant tank circuits are each referenced to the differential common mode point (120) for generating a differential output (OUT, OUTX).
摘要:
A method and apparatus for tuning the voltage controlled oscillator (VCO) (110) of a Phase Locked Loop (100) by comparing the VCO (110) voltage control line (116) to reference voltage (V.sub.1). With feedback, the voltage control line (116) is driven to the reference voltage level (V.sub.1).
摘要:
A selective call receiver (100) for receiving and transmitting paging signals has a transceiver (104) having an integer divide synthesizer (105) for achieving a fast lock time. The transceiver (104) has a reference oscillator (202) that generates a reference signal in a direct injection path and a modulator (206) coupled in the direct injection path modulates the reference signal to generate a modulated reference signal. A phase locked offset loop (220) coupled to the direct injection path generates a low frequency signal derived from the reference signal, a multiplier (210) coupled to the modulator (206) multiplies the modulated reference signal, and a mixer (214) coupled to the multiplier (210) receives the modulated reference signal in the direct injection path and an output signal from the phase locked offset loop (220) to generate a first local oscillator output signal and a modulated transmit carrier.
摘要:
A method and apparatus for improving signal reception in a receiver (100) by performing all-channel and/or on-channel estimations on a received signal so as to predict future RF environments. The prediction is achieved through the use of one or more detector systems (122, 124) positioned to sample and detect predetermined signal metrics of the received signal (103) prior to analog-to-digital conversion (112) and subsequent post-processing (114). Future estimations of the channel condition are thus generated prior to the arrival of the actual samples (115) at a controller section (116). The detectors (122, 124) provide triggers (123, 125) to the controller (116) so that active stages (130) within the receiver (100) can be adjusted and scaled as needed via a serial port interface (SPI) (126) based on signal conditions.
摘要:
A method and apparatus for improving signal reception in a receiver (100) by performing all-channel and/or on-channel estimations on a received signal so as to predict future RF environments. The prediction is achieved through the use of one or more detector systems (122, 124) positioned to sample and detect predetermined signal metrics of the received signal (103) prior to analog-to-digital conversion (112) and subsequent post-processing (114). Future estimations of the channel condition are thus generated prior to the arrival of the actual samples (115) at a controller section (116). The detectors (122, 124) provide triggers (123, 125) to the controller (116) so that active stages (130) within the receiver (100) can be adjusted and scaled as needed via a serial port interface (SPI) (126) based on signal conditions.
摘要:
Systems and method for reducing phase imbalance in radio frequency (RF) signals are disclosed. The phase imbalance in an RF signal may be due to phase imbalance in the local oscillator used for upconversion in a transmitter, and downconversion in a receiver. The RF signal is converted to a digital signal. The phase imbalance in the digital signal is measured by using a digital signal processor. The digital signal processor generates a compensation signal in response to the measurement of the phase imbalance. The compensation signal is used to generate a tuning signal to tune the local oscillator used for the upconversion or downconversion, thereby reducing the phase imbalance.