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:
A DC offset correction method and apparatus. In a DC offset correction loop (100), a DC offset is corrected using a binary search routine or any other digital or analog DC offset correction technique. In this binary search routine, the sign of the offset (138) is used to control a direction in which a digital to analog converter (DAC) (166) is stepped until the least significant bit of the DAC is set. The process is enhanced by opening up the bandwidth of the baseband filters (130) to permit the binary search to be clocked (180) at a higher clock rate. After the correction is established, the filters (130) are reset to normal operating conditions.
摘要:
A DC offset correction loop (200) utilizes a sign bit generator (204), binary search stage (206), and a digital-to-analog converter (208) in its feedback path to correct for DC offsets at the input of a gain stage (202). When a correction value is obtained, it is applied and held (524) to compensate for the DC offset. When a programming event occurs (534), such as detecting an increase in DC offset beyond a threshold, detecting a significant temperature change, or passage of time, a new DC offset correction cycle is initiated.
摘要:
A DC offset correction loop (200) utilizes a sign bit generator (204), binary search stage (206), and a digital-to-analog converter (208) in its feedback path to correct for DC offsets at the input of a gain stage (202).
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 method and an apparatus (300) for generating corrected quadrature phase signal pairs in a communication device are provided. The apparatus (300) includes a quadrature phase generator (310), programmable delay elements (320, 330) and a control circuit (360). The programmable delay elements (320, 330) receive a quadrature phase signal pair (signals I 312 and Q 314) from the quadrature phase generator (310). The control circuit (360) generates a control signal (362) based on outputs (325, 335) of the programmable delay elements (320, 330). The control signal (362) configures the programmable delay elements (320, 330). The programmable delay elements (320, 330) are configured to adjust delay between the signals I (312) and Q (314). The programmable delay elements (320, 330) are also used to adjust duty cycle for the quadrature phase signal pair to provide the corrected quadrature phase signal pair.
摘要:
A transceiver synthesizer includes components that enable it to be tuned non-invasively by software. The transceiver synthesizer includes a non-volatile memory (30) that can be non-invasively programmed with a digital value for each of a number of tuning variables. The digital values are converted by digital to analog converters (37, 38, 39) into tuning voltages. The tuning voltages are applied to voltage variable devices (60, 80, 95) that respond to changes in the applied tuning voltage to vary an operating characteristic thereof. The operating characteristics of the voltage variable devices (60, 80, 95) are non-invasively adjustable to tune the transceiver synthesizer for high and low port modulation deviation, reference oscillator make tolerance, automatic frequency control, reference oscillator temperature compensation etc.
摘要:
A transceiver (10) includes a dual port phase and magnitude balanced synthesizer modulator (60). The modulator (60) couples a modulation input to a voltage controlled oscillator (40) and to a reference oscillator (42) that are coupled together in a phase locked loop (44). The modulator 60 includes a magnitude balancing circuit (64) that divides a modulation input representing data or the like into a first modulation input signal applied to the reference oscillator (42) and a second modulation input signal for the voltage controlled oscillator (40). A phase balancing circuit (68) induces a negative phase shift in the second modulation input signal that is coupled to the voltage controlled oscillator (40) in order to compensate for the phase lag of the reference oscillator loop (44).
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.