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:
Jan. 19, 1999
Filed:
Mar. 13, 1996
Shakil Barkat, Bartlett, IL (US);
Gregory Redmond Black, Vernon Hill, IL (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
A switching circuit (30) in a portable telephone connects a gate of a field-effect transistor (Q1) to a voltage below the transistor's gate threshold voltage when the voltage at a first power source terminal (B) falls below a threshold voltage, thus disconnecting the first power source terminal (B) from a portable telephone power input terminal (B+) and connecting a second power source terminal (A) to the power input terminal (B+). The threshold voltage is set at a voltage above the minimum supply voltage of the portable telephone. The first power source terminal may be connected to a main battery and the second power source terminal may be connected to an adapter such as a battery eliminator adapter, hands-free adapter, or mobile transceiver adapter. This switching circuit prevents a call in progress from being disconnected when power sources are exchanged during a GSM burst.