Patent · US Expired

Switchable PLL circuit with constant amplification gradient

US5537448A · kind A · utility

9Cited by

8References

9Claims

0Family size

Assignee

Blaupunkt-Werke GmbH · DE

Inventors

Detlef Schwarz · Hannover, DE
Stefan Bartels · Bienenbüttel, DE

Key dates

Filing date	Mar 2, 1994
Grant date	Jul 16, 1996
Priority date	—
Expiry date	Mar 2, 2014

Classification

Technology area (CPC H)Electricity
CPC primaryH03L7/1075
WIPO fieldBasic communication processes
WIPO sectorElectrical engineering

Abstract

An improved Phase-Locked Loop (PLL) radio receiver circuit includes a phase detector, either an active loop filter or a set of parallel, alternately selectable loop filters, and a Voltage-Controlled Oscillator (VCO) whose input is connected to the output of the loop filter. The output of the VCO is fed to frequency divider. The output of the frequency divider and a reference frequency signal form the inputs to the phase detector/comparator. Toggling among the loop filters occurs such that the loop limit frequency, defined by a loop amplification of 1, is altered by this toggling without significantly changing the gradient of the amplification to the frequency, in a frequency range which includes the limit frequency.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.