Patent Number:
7,088,962
Title:
On-chip loop filter for a PLL
Abstract:
An on-chip loop filter includes a 1.sup.st resistor, a 1.sup.st capacitor, a 2.sup.nd capacitor, a 3.sup.rd capacitor, a 2.sup.nd resistor, and a 4.sup.th capacitor. The 1.sup.st resistor is operably coupled to receive a charge pump output. The 1.sup.st capacitor is coupled in series with the 1.sup.st resistor where the second node of the 1.sup.st capacitor is coupled to a return. The 2.sup.nd capacitor is coupled in parallel with the series combination of the 1.sup.st resistor and 1.sup.st capacitor. The 3.sup.rd capacitor is coupled in parallel with the 2.sup.nd capacitor. The 2.sup.nd resistor is coupled to a node of the 3.sup.rd capacitor and to a node of the 4.sup.th capacitor. The other node of the 4.sup.th capacitor is coupled to ground. To enable these components to be placed on-chip, the 1.sup.st capacitor is of a 1.sup.st capacitor construct having a 1.sup.st quality factor, the 2.sup.nd capacitor is of a 2.sup.nd capacitor construct having a 2.sup.nd quality factor, where the 2.sup.nd quality factor is greater than the 1.sup.st quality factor, and the 3.sup.rd and 4.sup.th capacitors are of a 3.sup.rd capacitor construct having a 3.sup.rd quality factor, which is greater than the 2.sup.nd quality factor.
Inventors:
Anand; Seema B. (Beverly Hills, CA), Wu; Stephen (Fountain Valley, CA)
Assignee:
Broadcom Corporation
International Classification:
H04B 1/40 (20060101); H04B 1/06 (20060101); H04B 7/00 (20060101)
Expiration Date:
8/08/02018