Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Current driver
Patent
1996-02-07
1997-09-09
Callahan, Timothy P.
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Current driver
326 30, H03K 190185
Patent
active
056660782
ABSTRACT:
An output driver circuit is disclosed that generates an accurate and predictable output impedance driver value corresponding to a programmable external impedance. The output driver circuit includes an external resistance device, voltage comparator device, control logic, an evaluate circuit and off-chip driver (OCD) circuit. Voltage from the external resistance device (VZQ) is compared with voltage created from the evaluate circuit (VEVAL) by the voltage comparator device, which indicates to the control logic whether VEVAL is greater than or less than VZQ. The control logic will adjust the evaluate circuit accordingly with a count until the two voltages are basically equal (i.e., the count is alternating between two adjacent binary count values). At which time the control logic operates the OCD with the lower of the two adjacent count values to produce a proper and predictable driving impedance.
REFERENCES:
Thaddeus J. Gabara and Scott C. Knauer; Digitally Adjustable Resistors in CMOS for High-Performance Applications; Mar. 12, 1992.
Lamphier Steven H.
Pilo Harold
Schneiderwind Michael J.
Towler Fred J.
Callahan Timothy P.
International Business Machines - Corporation
Nu Ton My-Trang
Walter, Jr. Howard J.
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