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:
May. 24, 1994
Filed:
Nov. 16, 1992
Lloyd F Linder, Agora Hills, CA (US);
Dwight D Birdsall, Norwalk, CA (US);
Kelvin T Tran, Carson, CA (US);
Hughes Aircraft Company, Los Angeles, CA (US);
Abstract
A bandgap reference voltage source (104) has positive and negative terminals (104a,104b) which are connected through high impedance constant current sources (124c,126c) to positive and negative voltage supplies (+VDD,-VEE) respectively. The effect of variations of the voltage supplies (+VDD, -VEE) on the voltage source (104) is low due to the high impedances of the currents sources (124c,126c), providing a high power supply rejection ratio (PSRR). The reference voltage (VREF) generated by the voltage source (104) is converted into a reference current (IREF) which flows through two equal series resistors (108,110), and also through current mirrors (124,126) which produce positive and negative output currents corresponding thereto. The current sources (124c,126c) for the voltage source (104) are also controlled by the current mirrors (124,126). A servo control amplifier (232) senses the voltage at the junction (234) of the resistors (108,110) and adjusts the voltage at either the positive or negative terminal (104a,104b) of the voltage source (104) to maintain the voltages at the terminals (104a,104b) symmetrical with respect to ground, thereby preventing the voltage source (104) from latching to one of the voltage supplies (+VDD,-VEE) during startup.