Abstract: Aspects of a method and system for implementing a low power, high performance fractional-N PLL synthesizer are provided. The synthesizer comprises a reference generator/buffer, a charge pump, a divider, a VCO, a loop filter, and a phase-frequency detector (PFD). The reference generator/buffer may increase the frequency of the input reference signal to the PFD. The PFD may generate a single signal for controlling the charge pump utilizing the increased frequency input reference signal and a divider signal generated by the divider whose input frequency may be substantially the same as that of a VCO output signal. The single signal charges a charge up portion of the charge pump and a charge down portion is charged by a leakage current. The VCO signal may be generated based on a filtered output of the charge pump generated by the loop filter. The divider may utilize true single phase clock (TSPC) logic.

Abstract: Certain aspects of a method and system for mitigating effects of pulling in multiple phase locked loops in multi-standard systems may include selecting an input frequency range of operation at a voltage controlled oscillator based on a particular wireless band of operation in a system that handles a first wireless communication protocol and a second wireless communication protocol. An image rejection mixer may be enabled to generate an output signal for the particular wireless band of operation based on mixing a plurality of received signals within a selected frequency range. An in-phase (I) component and a quadrature (Q) component of the generated output signal may be generated by utilizing a RC-CR quadrature network.

Abstract: A novel circuit for obtaining the bandwidth of a phase-locked loop circuit is disclosed. The circuit adjusts a phase of a signal (reference or generated), causing the phase-locked loop circuit to adjust the frequency of its voltage-controlled oscillator as it recovers a phase lock. The circuit times the duration of the recovery stage, from which the loop bandwidth may be obtained. Adjustments to the programmable portions of the phase-locked loop may then be made in accordance with design specifications.

Abstract: A method and circuit for selecting the band of a multi-band voltage controlled oscillator in a phase locked loop is described. In one implementation, the circuit comprises a voltage controlled oscillator, a selection circuit for selecting a band for the voltage controlled oscillator from a plurality of predetermined bands, a decision circuit for determining if the selection circuit should select a new band from the plurality of predetermined bands, and a charging circuit for adjusting the input voltage into the voltage controlled oscillator.

Abstract: A method and circuit for selecting the band of a multi-band voltage controlled oscillator in a phase locked loop is described. In one implementation, the circuit comprises a voltage controlled oscillator, a selection circuit for selecting a band for the voltage controlled oscillator from a plurality of predetermined bands, a decision circuit for determining if the selection circuit should select a new band from the plurality of predetermined bands, and a charging circuit for adjusting the input voltage into the voltage controlled oscillator.

Abstract: Stable, robust, and high-resolution delta-sigma error feedback modulators, such as those used in digital-to-analog converters and phase-locked loops, include an L-order noise transfer function that is provided with L+1 high-order bits from a truncation element. The stability of such delta-sigma error feedback modulators is independent of the input signal. Moreover, the out-of-band gain of the noise transfer function need not be limited, which improves the resolution and the signal-to-noise ratio of the in-band signal.

Abstract: Stable, robust, and high-resolution delta-sigma error feedback modulators, such as those used in digital-to-analog converters and phase-locked loops, include an L-order noise transfer function that is provided with L+1 high-order bits from a truncation element. The stability of such delta-sigma error feedback modulators is independent of the input signal. Moreover, the out-of-band gain of the noise transfer function need not be limited, which improves the resolution and the signal-to-noise ratio of the in-band signal.

Abstract: A circuit for controlling the loss of a VCO in a master-slave tuning system includes an envelope detector, an amplitude regulator, a current-mode circuit, and a low-pass filter. The envelope detector receives the VCO output voltage and provides VCO output envelope voltage, V.sub.ENV. The amplitude regulator receives V.sub.ENV and a reference voltage, V.sub.REF, and provides a sourcing current if V.sub.ENV is less than V.sub.REF, and draws a sinking current if V.sub.ENV is greater than V.sub.REF. The current-mode circuit receives V.sub.ENV and provides a control current, I.sub.Q. The low-pass filter has high DC gain for integrating the control current and the sourcing or sinking current to provide the VCO control voltage, V.sub.CON, to the VCO. The control current, I.sub.Q, is proportional to the inverse of V.sub.ENV multiplied by the time derivative of V.sub.ENV.