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US 6,639,530 B2Granted
Modulation of an analog signal into a digital representation thereof
AssigneeBroadcom Corporation
InventorsHenrik Jensen, Brima Ibrahim
Life of this patent
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Abstract
A method and apparatus for modulating a signal into a digital representation thereof includes processing that begins by integrating a difference between an input signal and an analog feedback signal to produce an integrated signal. The processing then continues by quantizing the integrated signal to produce a quantized signal. The processing continues by generating a spectral shaping signal to compensate for non-linearities of the analog feedback signal. The processing further continues by injecting the spectral shaping signal into the quantized signal to produce a spectrally adjusted quantized signal. The processing further continues by converting the spectrally adjusted quantized signal into the analog feedback signal.
Claims15
A Delta Sigma modulator comprises:
- cascaded integrators operably coupled to integrate a difference between an analog input and an analog feedback signal to produce an integrated signal;
- quantizer operably coupled to quantize the integrated signal to produce a three-level quantized signal;
- spectral shaping module operably coupled to receive the quantized signal, wherein the spectral shaping module produces a spectrally adjusted quantized signal having:
- a first logic value when the three-level quantized signal is at a first level,
- a second logic value or a third logic value when the three-level quantized signal is at a second level, wherein the second logic value or the third logic value is determined in accordance with a random selection pattern, and
- a fourth logic value when the three-level quantized signal is at a third level;
- and
- the digital-to-analog feedback section including at least one digital-to-analog converter that includes two current sources that produce the analog feedback signal in one of three states based on the spectrally adjusted quantized signal, wherein the at least one digital-to-analog converter produces:
- a first state of the three states by disabling both of the two currents sources when the spectrally adjusted quantized signal is the first logic value,
- a second state of the three states by enabling one of the two current sources and disabling another of the two current sources when the spectrally adjusted quantized signal is the second logic value,
- or enabling the another of the two current sources and disabling the one of the two current sources when the spectrally adjusted quantized signal is the third logic value, and
- a third state of the three states by enabling both of the two current sources when the spectrally adjusted quantized signal is the fourth logic value.
9 more elements
A method for modulating an analog signal into a digital signal, the method comprises:
- integrating a difference between an analog input and an analog feedback signal to produce an integrated signal;
- quantizing the integrated signal to produce a three-level quantized signal, wherein the three-level quantized signal is representative of the digital signal;
- generating a spectral shaping signal to compensate for non-linearities of the analog feedback signal;
- injecting the spectral shaping signal into the quantized signal to produce a spectrally adjusted quantized signal, wherein the spectrally adjusted quantized signal has:
- a first logic value when the three-level quantized signal is at a first level,
- a second logic value or a third logic value when the three-level quantized signal is at a second level, wherein the second logic value or the third logic value is determined in accordance with a random selection pattern as indicated by the spectral shaping signal, and
- a fourth logic value when the three-level quantized signal is at a third level;
- and
- converting the spectral adjusted quantized signal into the analog feedback signal, wherein the analog feedback signal is one of three states, wherein the analog feedback signal is in:
- a first state of the three states when the spectrally adjusted quantized signal is the first logic value,
- a first representation of a second state of the three states when the spectrally adjusted quantized signal is the second logic value,
- a second representation of the second state of the three states when the spectrally adjusted quantized signal is the third logic value, and a third state of the three states when the spectrally adjusted quantized signal is the fourth logic value.
9 more elements
An apparatus for modulating an analog signal into a digital signal, the apparatus comprises:
- processing module:
- and
- memory operably coupled to the processing module, wherein the memory includes operational instructions that cause the processing module to:
- integrate a difference between an analog input and an analog feedback signal to produce an integrated signal;
- quantize the integrated signal to produce a three-level quantized signal, wherein the three-level quantized signal is representative of the digital signal;
- generate a spectral shaping signal to compensate for non-linearities of the analog feedback signal;
- inject the spectral shaping signal into the quantized signal to produce a spectrally adjusted quantized signal, wherein the spectrally adjusted quantized signal has:
- a first logic value when the three-level quantized signal is at a first level,
- a second logic value or a third logic value when the three-level quantized signal is at a second level, wherein the second logic value or the third logic value is determined in accordance with a random selection pattern as indicated by the spectral shaping signal, and
- a fourth logic value when the three-level quantized signal is at a third level;
- and
- convert the spectral adjusted quantized signal into the analog feedback signal, wherein the analog feedback signal is one of three states, wherein the analog feedback signal is in:
- a first state of the three states when the spectrally adjusted quantized signal is the first logic value,
- a first representation of a second state of the three states when the spectrally adjusted quantized signal is the second logic value,
- a second representation of the second state of the three states when the spectrally adjusted quantized signal is the third logic value, and a third state of the three states when the spectrally adjusted quantized signal is the fourth logic value.
12 more elements
Dependencies are inferred from the claim text.