The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 16, 2003
Filed:
Sep. 04, 2002
Rodney A. Hughes, Tacoma, WA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A charge pump comprises a first current mirror that injects a first charging current onto a loop filter and a second charging current onto an integrator capacitor. The first and second charging currents are controlled by a first common control signal. The first charging current mirrors the second charging current. A second current mirror drains a first discharging current from the loop filter and a second discharging current from the integrator capacitor. The first and second discharging currents are controlled by a second common control signal. The first discharging current mirrors the second discharging current. A sampling circuit couples the second charging and discharging currents to the integrator capacitor, which charges or discharges with a difference current between the second charging and discharging currents. A control circuit detects a voltage difference between the loop filter and integrator capacitor and adjusts the first common control signal to minimize the voltage difference.