| US 7,602,255 B1 | ||
| Loop circuits that reduce bandwidth variations | ||
| Kang-Wei Lai, Milpitas, Calif. (US); Ninh D. Ngo, Palo Alto, Calif. (US); Kazi Asaduzzaman, Fremont, Calif. (US); Mian Z. Smith, Los Altos, Calif. (US); Wanli Chang, Saratoga, Calif. (US); and Tim Tri Hoang, San Jose, Calif. (US) | ||
| Assigned to Altera Corporation, San Jose, Calif. (US) | ||
| Filed on Sep. 25, 2007, as Appl. No. 11/861,144. | ||
| Int. Cl. H03L 7/00 (2006.01) | ||
| U.S. Cl. 331—16 [331/34; 331/177 R; 331/176; 331/175; 331/185] | 20 Claims |
| 1. A circuit comprising a feedback loop, the feedback loop comprising:
a detector;
a charge pump that generates an output current in response to at least one output signal of the detector, wherein the charge
pump comprises a first current source generating a first current that varies based on threshold voltages of transistors in
the circuit; and
a loop filter coupled to the charge pump, wherein the charge pump adjusts the output current in response to variations in
a process of the circuit to reduce variations in a bandwidth of the feedback loop.
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