Phase Locked Loop with Frequency Monitor
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Disclosed is a circuit in which a highly stable Phase Locked Loop (PLL) has a wide capture range.
Loopwith Frequency Monitor
a circuit in which a highly stable Phase Locked
Loop (PLL) has a wide capture range.
monitor helps to enhance the capture range of a
PLL. A frequency synthesizer system consists of a Voltage Controlled
Oscillator (VCO) and a PLL .
A characteristics of PLL is that a highly accurate system is
apt to have a narrow operating range, whereas a PLL that works in a
wide operating range is apt to loose stability or accuracy. This
frequency monitor is attached to a highly accurate PLL, and brings
the oscillation frequency of the VCO into the capture range of the
PLL when the PLL fail to control the VCO.
frequency monitor works exclusively with the PLL. When
the oscillation frequency is in the capture range of the PLL, the PLL
has control of the VCO, and the frequency monitor has control of the
VCO. when the oscillation frequency of the VCO is outside the
capture range of the PLL.