An effective technique for phase noise improvement in a fractional-N synthesizer is described. The method requires using in a 90" phase shift lock a non-linear continuous-time or sampled-data block before the loop filter. Behavioral simulations on a fractional-N synthesizer incorporating different non-linear blocks and a second-order single bit sigma delta modulator show that it is possible to ...

1. Definition. A PLL is a feedback system that includes a VCO, phase detector, and low pass filter within its loop. Its purpose is to force the VCO to replicate and track the frequency and phase at the input when in lock. The PLL is a control system allowing one oscillator to track with another. It is possible to have a phase offset between input and output, but when locked, the frequencies mus...

Fully-integrated, high-frequency continuous-time filters can be reafized in MOS technology using a frequency-locking approach to stabilize the time constants. A simple fufly-differential integrator, optimized for phase-error cancellation, forms the basic element; a complete filter consists of intercoupled integrators. The center frequency of the filter is Ioeked to an extemaf reference frequenc...

A "trimethyl lock" system has been known to facilitate lactonization reactions through what has been termed a stereopopulation control mechanism. We have found that a similar trimethyl lock system can also facilitate cyclic ether formation with the concomitant release of a carboxylic acid in the presence of anhydrous tetrabutylammonium fluoride. To study this base-mediated trimethyl lock-facili...

We report a single-loop PLL that operates in a wide-bandwidth, fractional-N mode (with no fractional spur reduction scheme) during transient but in a narrow-bandwidth, integer-N mode during phase lock. This hybrid PLL, as an extension of the conventional fast-lock PLL (that shifts only its bandwidth while retaining the same frequency division mode), simultaneously achieves the fastlock advantag...