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. 30, 1999
Filed:
Apr. 16, 1997
Patrick P Siniscalchi, Sachse, TX (US);
Davy H Choi, Garland, TX (US);
William R Krenik, Garland, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A programmably variable transconductance circuit (10) and method for varying its transconductance includes first and second current control input devices (16, 18), each having an input (17,19) to which a differential input voltage may be applied. A pair of current steering circuits (26, 28, 30, 32) are each connected in series with a respective one of the first and second current control devices (16, 18) for dividing respective currents in the first and second current control devices (16, 18) between a differential output current path (12, 14) and another current flow path, and a programmable voltage source (90) supplying V.sub.CONTROL is connected to control the current division by the current steering circuits (26, 28, 30, 32). The programmable voltage, V.sub.CONTROL, is provided by a programmable current control loop (90), which incorporates a master transconductance circuit, to establish a constant transconductance independently of temperature variations. A dynamically controllable resistance, such as an MOS transistor (24), or the like, is connected between the first and second current control input devices (16, 18), and a second voltage source (V.sub.GATE) is connected to the dynamically controllable resistance (24) to maintain the dynamically controllable resistance (24) at a constant value.