Variable delay element

• US 6,133,773 A
• Filed: 10/10/1997
• Issued: 10/17/2000
• Est. Priority Date: 10/10/1997
• Status: Expired due to Term

• Current Assignee: Rambus Inc.
• Original Assignee: Rambus Inc.
• Inventors: Sidiropoulos, Stefanos, Stark, Donald C., Portmann, Clemenz, Donnelly, Kevin S., Yu, Leung, Chau, Pak Shing, Lau, Benedict Chung-Kwong, Vu, Roxanne, Garlepp, Bruno Werner
• Primary Examiner(s): LE, DINH THANH
• Application Number:
  US08/947,477
• Time in Patent Office: 1,103 Days
• Field of Search: 327/246, 327/277, 327/287, 327/3, 327/156, 327/237, 327/231, 327/266, 327/274, 327/20
• US Class Current: 327/247
• CPC Class Codes: H03K 2005/00065 by current control, e.g. by parallel current control transistors
• CPC Class Codes: H03K 2005/00071 by adding capacitance as a load
• CPC Class Codes: H03K 2005/00163 using bipolar transistors
• CPC Class Codes: H03K 2005/00202 using current mirrors
• CPC Class Codes: H03K 2005/00208 using differential stages
• CPC Class Codes: H03K 2005/00286 Phase shifter, i.e. the delay between the output and input pulse is dependent on the frequency, and such that a phase difference is obtained independent of the frequency
• CPC Class Codes: H03K 5/13 Arrangements having a single output and transforming input signals into pulses delivered at desired time intervals

Abstract

A method and apparatus for an adjustable phase interpolator is provided. The adjustable phase interpolator includes a phase interpolator circuit that has a voltage input and a voltage output. The adjustable phase interpolator further includes a controllable capacitive load coupled to either the input or the output of the phase interpolator circuit. The controllable capacitive load is designed to add or subtract capacitance to the adjustable phase interpolator.

Claims