US 2004/0164812 A1 · Fully integrated broadband tuner

Abstract

A fully integrated single-loop frequency synthesizer, which can serve as a local oscillator for a broadband tuner, is disclosed, thus allowing the creation of a single-chip solution for broadband applications. The tank circuits are integrated into the tuner chip through the combination of a phase-locked loop and multiple on-chip VCOs comprising narrow-tuning range varactors. Drift in the VCOs caused by heat is overcome by designing the VCOs to overlap each other. Initial tolerance problems associated with the VCOs are overcome by the use of a calibration method. The calibration of the VCOs is accomplished by utilizing the lock detect output of the phase-locked loop and a binary search algorithm. The edges of each VCO are determined with this calibration method, thereby enabling VCO selection based on the desired channel. A sufficient number of VCOs are provided such that whatever the initial tolerance shift, the full broadband spectrum can still be covered after calibration. Additionally, the problem of coupling between the local oscillator signal and the incoming radio frequency signal is mediated by the use of a programmable 2/4 divider. This 2/4 divider also provides additional flexibility in choosing the number of VCOs to put on the chip and which VCO to use in a particular implementation.

Claims32

Dependent claims

A phase-locked loop frequency synthesizer comprising:

a phase/frequency detector that compares a reference frequency with an output frequency signal and generates an appropriate charge pump control voltage;
a charge pump coupled to said phase/frequency detector that generates a loop filter control current from the charge pump control voltage;
a loop filter coupled to said charge pump that generates a loop filter voltage;
an oscillator bank coupled to the loop filter comprising a plurality of voltage controlled oscillators;
a feedback circuit coupled between said oscillator bank and said phase/frequency detector that provides the output frequency signal to the phase/frequency detector;
and
a logic interface coupled to said oscillator bank for enabling one of said voltage controlled oscillators at a time.

4 more elements

Dependencies are inferred from the claim text.

Fully integrated broadband tuner

Life of this patent

Fully integrated broadband tuner

Life of this patent

Abstract

Claims32