PLLs may include a divider between the oscillator and the feedback input to the phase detector to produce a frequency synthesizer.
12.
Phase-locked loop frequency synthesizers make use of frequency dividers to generate a frequency that is a multiple of a reference frequency.
13.
The LO signal is generated by a Gunn diode oscillator whose frequency is controlled via a phase-lock loop system by a computer-controlled frequency synthesizer.
14.
The key to the ability of a frequency synthesizer to generate multiple frequencies is the divider placed between the output and the feedback input.
15.
Thus, in a PLL frequency synthesizer there are two buses, one for the reference counter, the other for the output ( or VCO ) counter.
16.
In practice this type of frequency synthesizer cannot operate over a very wide range of frequencies, because the comparator will have a limited varactor diodes.
17.
Their disadvantage is that changing frequency ( more than a small amount ) requires changing the crystal, but frequency synthesizer techniques have made this unnecessary in modern designs.
18.
His doctoral dissertation on " Architectures, Optimization Techniques, and VLSI Implementations for Direct Digital Frequency Synthesizers " became the basis for the development of the chip that launched Broadcom.
19.
In the 1970s, receivers began to be designed using frequency synthesizer circuits, which synthesized the receiver's input frequency from a crystal oscillator using the vibrations of an ultra-stable quartz crystal.
20.
With the advent of digital frequency synthesizers that could be set with high resolution by a keypad or incremental tuning knob, the requirement for bandspread control in many applications was eliminated.
