Dual independently clocked analog-to-digital conversion for...

Details Dual independently clocked analog-to-digital conversion for... Dual independently clocked analog-to-digital conversion for...

2001-02-28

2002-02-19

Pascal, Robert (Department: 2817)

Amplifiers

Modulator-demodulator-type amplifier

C330S20700P, C375S238000

Reexamination Certificate

active

06348836

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to noise-shaping digital amplifiers, and specifically to techniques for using and generating multiple and independent clocks in such amplifiers. It should be noted at the outset that although the invention is described herein with reference to a bandpass (e.g., RF) implementation, the present invention is also applicable to other amplifier configurations such as, for example, baseband audio amplifiers and motor drive circuits.
FIG. 1
shows an RF bandpass noise-shaping amplifier
100
designed according to techniques described in U.S. Pat. No. 5,777,512 for METHOD AND APPARATUS FOR OVERSAMPLED, NOISE-SHAPING, MIXED-SIGNAL PROCESSING issued Jul. 7, 1998, the entire disclosure of which is incorporated herein by reference for all purposes. RF amplifier
100
includes a frequency selective network
102
which, using continuous-time feedback, noise shapes the modulated RF input. Network
102
comprises at least one resonator stage having a transfer function designed to pass a band centered around 900 MHz.
A/D converter
104
converts the noise shaped RF signal to digital data using a sampling frequency fs which, in this example, is 3.6 GHz. A/D converter
104
may comprise a comparator.
Gate drive circuitry
106
takes the pulse train from A/D converter
104
and generates gate drive for each of FETs
108
and
110
of the power output stage of amplifier
100
. The output power stage shown includes three inductors L
1
, L
2
and L
3
, and capacitor C
1
. This configuration creates two separate resonances at nodes A and B respectively when the corresponding one of FETs
108
and
110
is off.
The continuous-time feedback to frequency selective network
102
is provided via feedback path
112
. The output signal of the power stage is passed to a matching network
114
which passes the output RF signal to antenna
116
for transmission.
As will be understood, the amplifier configuration of
FIG. 1
allows for two quantization states. With two quantization states there is a high number of signal transitions resulting in high drive losses. Therefore, it is desirable to provide techniques by which such losses may be mitigated or eliminated.
SUMMARY OF THE INVENTION
According to the present invention, an amplifier architecture is provided in which multi-level switching is enabled. That is, the amplifier architecture described herein exhibits more than two quantization states. This is achieved, in part, with parallel signal paths each of which has its own sampling circuitry. The multiple quantization states includes a state in which there is no signal output, thereby avoiding the undesirable switching losses described above. According to a specific embodiment, the clock signals for the different sampling circuits are independently developed resulting in a variety of other advantages.
Thus, the present invention provides an electronic device which includes at least two sampling circuits, and at least two switching stages configured in parallel. Each of the switching stages is coupled to one of the sampling circuits. The sampling circuits and the switching stages enable the electronic device to exhibit more than two quantization states. The electronic device further includes clock generation circuitry for generating independent clock signals for each of the sampling circuits.
A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings.


REFERENCES:
patent: 4326170 (1982-04-01), Levy
patent: 4667144 (1987-05-01), Jones et al.
patent: 4949048 (1990-08-01), Tokumo et al.
patent: 5023566 (1991-06-01), El-Hamamsy et al.
patent: 5479337 (1995-12-01), Voigt
patent: 5777512 (1998-07-01), Tripathi et al.
patent: 5781067 (1998-07-01), Tota
patent: 6130910 (2000-10-01), Anderson et al.
Karsten Nielson, “High-Fidelity PWM-Based Amplifier Concept For Active Loudspeaker Systems With Very Low Energy Consumption”,J. Audio Eng. Soc., vol. 45 No. 7/8, Jul./Aug. 1997, pp. 555-570.

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