Phase-locked loop circuit with switchable outputs for multiple loop filters

Patent

Phase-locked loop circuit with switchable outputs for multiple loop filters

- 22 Dec 1997

12

TL;DR: In this article, an electronic system, such as a wireless telephone handset (10), having multiple voltage-controlled oscillators (26, 28) so that the system can operate in a selected one of multiple frequency bands, is disclosed.

Abstract: An electronic system, such as a wireless telephone handset (10), having multiple voltage-controlled oscillators (26, 28) so that the system can operate in a selected one of multiple frequency bands, is disclosed. Each of the voltage-controlled oscillators (26, 28) is associated with one of multiple loop filters (32, 34), which filter the control voltage (CP1, CP2) responsive to which the frequency of oscillation of the voltage-controlled oscillators (26, 28) controlled. Only one of the voltage-controlled oscillators (26, 28) is enabled at any one time, responsive to a control signal (VCOSEL). Synthesizer circuitry (30) includes a phase detector (44) which is coupled to a common node (VCOCLK) at which outputs of the voltage-controlled oscillators (26, 28) are coupled; the phase detector (44) compares the phase of this signal (VCODIV) to a reference signal (REFDIV) based on a reference clock (REFCLK), and controls a charge pump (46) accordingly. A switch (48) is provided to selectably apply the output of the charge pump (46) to the loop filter (32, 34) associated with the selected voltage-controlled oscillator (26, 28).

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Citations

Patent

Low power fractional pulse generation in frequency tracking multi-band fractional-N phase lock loop

Khaled Sharaf, +1 more

- 21 Dec 1998

TL;DR: In this article, a dynamic power approach where the compensation circuitry is biased only during the fractional portion of the cycle is proposed to provide the advantages of fractional-N synthesizers with spur suppression, such as higher speed and lower phase noise with ultra low power dissipation.

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24

Patent

Self-calibrating shared-component dual synthesizer

Sudipto Chakraborty, +1 more

- 20 Dec 2013

TL;DR: In this paper, a self-calibrating shared-component dual synthesizer includes two frequency synthesizers that are adapted to operate (respectively) in transmit (TX) and receive (RX) modes.

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Patent

Fractional-spurs suppression scheme in frequency tracking multi-band fractional-N phase lock loop

Abdellatif Bellaouar, +2 more

- 21 Dec 1998

TL;DR: In this paper, the authors used fractional compensation timing circuitry to track a VCO output frequency, f O, and provide highly effective error cancellation in a fractional-N PLL synthesizer.

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22

Patent

Receiver capable of selecting optimal voltage controlled oscillator

Shuichi Ninomiya

- 21 May 1999

TL;DR: In this paper, a receive control portion activates each of VCOs, and then sets a reference dividing ratio N typ in the programmable divider, which determines whether the PLL circuit locks or not based on a signal inputted during this time.

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21

Patent

Multiband frequency generation using a single PLL-circuit

Christian Ries

- 29 Nov 2000

TL;DR: In this article, the output terminals of a voltage-controlled multiband oscillator (22-1,..., 22-N) are coupled to a frequency synthesis unit (10) via a frequency selective coupling unit (24).

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17

References

Patent

Phase lock loop having switchable filters and oscillators

Dickes Eric Jon, +2 more

- 22 Jul 1982

TL;DR: In this paper, a phase lock circuit including a phase/frequency detector, a plurality of selectable filters, and variable frequency signal generators are connected in a loop to lock an output signal to an input signal.

...read moreread less

46

Patent

Multiple accumulator fractional N synthesis with series recombination

Hietala Alexander W

- 18 Feb 1992

TL;DR: A fractional-N type frequency synthesizer (700) for use in a radiotelephone (901) is described in this article, where the synthesizer utilizes multiple latched accumulators within an accumulator network, to perform multiple integrals of an input signal.

...read moreread less

37

Patent

Phase-locked digital synthesiser

Haine John Leslie

- 29 Jul 1986

TL;DR: A phase-locked digital synthesizer as mentioned in this paper comprises a voltage-controlled oscillator (6) supplying a frequency divider (7) the output of which is fed to a phase-sensitive detector (9) also receiving an input from a reference oscillator.

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27

Patent

Switchable filter phase-locked loop frequency synthesizer device and method for achieving dual-mode cellular communications

Winston H. Lieu

- 09 Aug 1994

TL;DR: In this article, a cellular telecommunication device consisting of switchable loop filters, a loop filter switch controller, a programmable frequency synthesizer, and a voltage controlled oscillator arranged in a phase-locked loop configuration is described.

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