(12) United States Patent ao) Patent No.: us 6,657,468 Bi
Best et al. (45) Date of Patent: Dec. 2,2003
Glasser et al., "The Design and Analysis of VLSI Circuits", Addison-Wesley Publishing Company, Copyright© 1985.
* cited by examiner
Primary Examiner—Dinh T. Le
(74) Attorney, Agent, or Firm—Pennie & Edmonds LLP (57) ABSTRACT
A circuit to control the edge rate of a digital signal includes a conductor to carry a digital signal. A first capacitive component has a first node and a second node, with the second node being coupled to the conductor. A first phase control circuit has a first input node coupled to the conductor, a second input node to receive a first enable signal and an output node coupled to the first node of the first capacitive component. The first phase control circuit processes the digital signal from the conductor and the first enable signal to produce a control signal at the output node to control the edge rate of the digital signal. The first phase control circuit produces the control signal in one of at least two different phase relationships with the digital signal according to a state of the first enable signal. The control signal may be in phase with the digital signal or complementary to the digital signal.
21 Claims, 10 Drawing Sheets