| US 7,579,918 B2 | ||
| Clock generator with reduced electromagnetic interference for DC-DC converters | ||
| Kuo-Chun Hsu, Miaoli (Taiwan) | ||
| Assigned to Taiwan Semiconductor Manufacturing Co., Ltd., Hsin-Chu (Taiwan); and Global Unichip Corp., Hsin-Chu (Taiwan) | ||
| Filed on Dec. 28, 2006, as Appl. No. 11/647,626. | ||
| Prior Publication US 2008/0157831 A1, Jul. 03, 2008 | ||
| Int. Cl. H03K 3/02 (2006.01) | ||
| U.S. Cl. 331—143 [331/111; 331/177 R; 327/132; 323/282] | 19 Claims |
| 1. A clock generator comprising:
a current source for generating a constant current;
a current mirror coupled between a supply voltage and the current source for generating a mirror current equal to the constant
current multiplied by a predetermined value; and
a charge control module coupled with the current source and the current mirror for charging a capacitor when a voltage thereof
is lower than a predetermined threshold voltage and for discharging the capacitor when the voltage thereof is higher than
the predetermined threshold voltage, thereby generating a clock signal at a predetermined frequency, wherein the charge control
module includes a multiplexer coupled to the current source for receiving input signals having various voltage levels from
the current source,
wherein the charge control module adjusts the predetermined frequency by selecting the voltage level of the input signals
received from the current source to change the predetermined threshold voltage.
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