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:
Nov. 21, 1995
Filed:
Dec. 07, 1994
Trung T Nguyen, San Jose, CA (US);
Jin Zhao, Milpitas, CA (US);
LSI Logic Corporation, Milpitas, CA (US);
Abstract
A bias voltage generator for a voltage controlled oscillator is described. In one aspect of the invention, the bias voltage generator includes a biasing circuit to generate a minimum clock output at zero operating voltage, and includes a common mode rejection circuit for the BIASN and BIASP control voltages for the differential delay stages and a IDD test current shut-down circuit. A differential delay stage is described that includes a current source controlled by the BIASN and BIASP control voltages from the bias voltage generator, a resistance linearization circuit for current controlling transistors of a BIASN circuit, and a process variation circuit for compensating for temperature and process variations. The improved characteristics of the resulting VCO permits high frequency operation with a relatively low gain, relatively constant gain throughout operating voltage range, improved noise rejection capabilities, increased speed of delay stage, and reduced output signal swing. All of which contribute to improved phase locked loop reliability especially when operating near the ends of the operating range.