Gain ranging analog-to-digital converter with error correction

Details Gain ranging analog-to-digital converter with error correction Gain ranging analog-to-digital converter with error correction

1998-10-08

2001-08-07

Jeanpierre, Peguy (Department: 2819)

Coded data generation or conversion

Analog to or from digital conversion

Nonlinear

C341S155000

Reexamination Certificate

active

06271780

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention pertains in general to Analog-to-Digital Converters and, more particularly, to a Gain Ranging Analog-to-Digital Converter.
BACKGROUND OF THE INVENTION
In order to increase the dynamic range for Analog-to-Digital Converters, a technique known as “gain ranging” has been utilized. This technique requires two data conversion paths, each path having a different amplification associated therewith. A threshold detector determines the signal level on the input and then defines the signal path that is to be utilized. If it is below a defined low signal level threshold, the high gain path is utilized, and if it is above a predetermined high signal level threshold, the high gain path is utilized. If the signal level is detected as being between the two thresholds, then a “blending” of the two signals can be facilitated.
One disadvantage to the above-noted gain ranging technique is that, when the two digital signals are combined in the blending operation, it is important to ensure that the two paths have the same magnitude, phase and DC off-set characteristics. The DC off-set can be removed with a high pass filter in each path. However, any remaining mismatch due to gain or phase mismatch can result in audible distortion. It is this gain mismatch and phase mismatch that must be corrected for in order to ensure that the combining of the two digital outputs is achieved correctly to prevent such distortion.
SUMMARY OF THE INVENTION
The present invention disclosed and claimed herein comprises a digital microphone system including a gain ranging analog-to-digital convertor. The analog-to-digital convertor is operable to convert an analog signal to a digital signal and process a digital signal in the digital domain. During this conversion operation, a digital processing system is operable to detect the magnitude of this signal and vary the conversion gain thereof as a function of the magnitude of the signal. At least two digital signals are combined in this operation to yield a resulting digital signal with the combining operation including a phase equalization operation performed between the two combined signals to minimize distortion in the audio signal in the analog domain corresponding to the resulting digital signal in the digital domain.
In another aspect of the present invention, the analog-to-digital convertor comprises a high gain conversion path and a low gain conversion path, the high gain path imparting a first gain thereto and the low gain path imparting a second gain thereto lower than the first gain. A proportionality device is provided for varying the gain in at least one of the paths relative to the other of the paths. A summing device then sums the output of the high gain path and the low gain path with a controller controlling the proportionality device to determine the amount of signal to be summed from each of the high and low gain paths in accordance with a predetermined summing profile. An equalizer is provided in one of the paths for adjusting the fade between the high and low gain paths to minimize distortion in the resulting signal.


REFERENCES:
patent: 4010462 (1977-03-01), Armistead
patent: 4383247 (1983-05-01), Assard
patent: 4393369 (1983-07-01), Davies
patent: 4399416 (1983-08-01), Gillespie
patent: 4581595 (1986-04-01), Silagi
patent: 4584558 (1986-04-01), Maschek et al.
patent: 4674062 (1987-06-01), Premerlani
patent: 4817167 (1989-03-01), Gassmann
patent: 4851842 (1989-07-01), Iwamatsu
patent: 4999628 (1991-03-01), Kakubo et al.
patent: 5031193 (1991-07-01), Atkinson et al.
patent: 5245665 (1993-09-01), Lewis et al.
patent: 5506910 (1996-04-01), Miller et al.
patent: 5821889 (1998-10-01), Miller
patent: 5878335 (1999-03-01), Kushner
patent: 5999802 (1999-12-01), Aschwanden
patent: 6097324 (2000-08-01), Myer et al.
“20 Bit A-to-D & D-to-A Converting Systems for Digital Audio,” Yasunori Tani, Kozo Nuriya, Nobuyuki Seki and Tetsuhiko Kaneaki, IEEE Transactions on Consumer Electronics, vol. 35, No. 3, Aug. 1989, pp. 528-535.
“20 Bit A-to-D & D-to-A Converting Systems for Digital Audio”, Y. Tani, K. Nuriya, N. Seki and T. Kaneaki, IEEE 1989 International Conference on Consumer Electronics, Digest of Technical Papers, Jun. 6-9, 1989, pp. 210-211.

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