Coded data generation or conversion – Analog to or from digital conversion – Analog to digital conversion
Reexamination Certificate
2006-03-07
2006-03-07
JeanPierre, Peguy (Department: 2819)
Coded data generation or conversion
Analog to or from digital conversion
Analog to digital conversion
C341S118000, C341S172000
Reexamination Certificate
active
07009549
ABSTRACT:
A pipelined analog-to-digital converter (ADC) (30) with improved precision is disclosed. The pipelined ADC (30) includes a sequence of stages (20), each of which includes a sample-and-hold circuit (22), an analog-to-digital converter (23), and the functions of a digital-to-analog converter (DAC) (25), an adder (24), and a gain stage (27) at which a residue signal (RES) is generated for application to the next stage (20) in the sequence. A multiplying DAC (28) performs the functions of the DAC (25), adder (24), and gain stage (27) in the stage (20), and is based on an operational amplifier (29). Sample capacitors (C10, C20) and reference capacitors (C122, C222) receive the analog input from the sample-and-hold circuit (22) in a sample phase; parallel capacitors (C121, C221) are provided to maintain constant circuit gain. Extended reference voltages (VREFPX,VREFNX) at levels that exceed the output range (V0+, V0−) of the operational amplifier (29) are applied to the reference capacitors, in response to the digital output of the analog-to-digital converter (23) in its stage (20). The reference capacitors (C12, C22) are scaled according to the extent to which the extended reference voltages (VREFPX,VREFNX) exceed the op amp output levels (V0+, V0−). The effects of noise on the reference voltages (VREFPX,VREFNX) on the residue signal (RES) are thus greatly reduced.
REFERENCES:
patent: 6249240 (2001-06-01), Ballaouar
patent: 6909391 (2005-06-01), Rossi
patent: 6909393 (2005-06-01), Atriss et al.
Abo et al., “A 1.5 V, 10-bit, 14.3-MS/s CMOS Pipeline Analog-to-Digital Converter”, J. Solid State Circ., vol. 34, No. 5 (IEEE, May 1999), pp. 599-606.
Brady W. James
Jean-Pierre Peguy
Mai Lam T.
Swayze, Jr. W. Daniel
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