Phase-Locked Loop Circuit
In wireless applications, phase-locked-loop frequency synthesizers require very good phase noise performance in order to obtain a good signal-t-noise ratio for the desired signals even in the presence of very large nearby unwanted signals. Inside frequency synthesizers, thermal noise generated by the charge pump and resistors in the loop filter will modulate the voltage-controlled oscillator and degrade the phase noise performance. To reduce thermal noise, the capacitors thus required are too large to be put on the chip. As a result, off-chip capacitors need to be used and thus the product size and cost are inevitably increased. A split loop filter [US Patent 5,384,502] (also referred to as dual-loop filter) has been proposed as an effective solution to reduce these capacitors. However, its main problem is the requirement of a wide-dynamic-range voltage adder, which either causes a lot of noise or consumes a lot of power and chip area.
This new invention is a novel design based on the split loop filter not only to further reduce the size of the capacitors but also to provide many other critical advantages. The split loop filter is modified such that the output of the integrator and that of the low-pass filter are used to separately control two parallel voltage-controlled capacitors (varactors). As a result, the summing is inherently done in the capacitance domain, and a voltage adder is not needed. Moreover, the two paths in the loop filter become completely separated and can be independently optimized.
The use of this new phase-locked loop can reduce the total capacitance and the total chip area by around half while maintaining the same tuning range for the synthesizer. It is because a large signal magnitude in the low-pass filter's path can be used to maximize the signal-to-noise ratio whereas a small signal magnitude in the integrator's path can be used to provide the desired tuning range.
The proposed circuitry is much simpler and performs much better than all existing solutions not only in terms of less noise and lower supply voltage but also in terms of lower power consumption because a voltage adder - which would inevitably contribute a lot of noise, require a large dynamic range, and consume a lot power - is no longer needed.
- Frequency synthesizer for mobile phones and cordless phone
- Wireless and portable applications that require a high-performance frequency synthesizers
Patent Number: CN101338519B
Application Number: CN200810130446A
Inventor: XIN, Hao-zhong | FEI, Bin
Priority Date: 2 Jul 2007
Priority Number: CN101338519B
Application Date: 2 Jul 2008
Publication Date: 22 Jun 2011
IPC Current: D06M0015333 | D06M0015263 | D06M002312 | D06M010106 | D06M010110 | D06M010132 | D06M010134
Assignee Applicant: The Hong Kong University of Science & Technology
Title: Insect repellant fabrics and its manufacture method | Insect repellent fabric and manufacturing method thereof
Usefulness: Insect repellant fabrics and its manufacture method | Insect repellent fabric and manufacturing method thereof
Summary: The method is useful to prepare a prytheroid compound-treated fabric (preferably cottons, polyesters, blends, wool and nylons) (claimed), which is useful as insect repellant. The ability of (I) to repel insect (mosquito) was tested. The result showed that only one person was stung by 12 standing mosquitos in 2 minutes.
Novelty: Preparing prytheroid compound-treated fabric, comprises dissolving polysaccharide compound in aqueous solution, heating and adding prytheroid mixture to solution, initiating graft polymerization in solution and applying solution to fabric
电子
电路设计
12 Oct 2001
US 6538519
TTC.PA.116
香港
