Analog-to-digital converter circuit having automatic range control

A method for converting an analog signal having a time varying amplitude in a dynamic range to a digital signal using an analog to digital converter having a digital output ranging from zero to full scale comprising:

• (a) sensing the amplitude of the analog signal;
• (b) determining the occurrence of a preselected event;
• (c) detecting a first peak amplitude of the sensed analog signal following the occurrence of a preselected event;
• (d) providing a reference potential corresponding to the detected first peak amplitude;
• (e) converting the analog signal sensed following the occurrence of a preselected event to a digital signal based on a relationship between the analog signal and the reference potential;
• and
• (f) repeating steps (c), (d), and (e) in response to the occurrence of each detected preselected event.

An apparatus for converting a sensed analog signal having a time varying amplitude within the dynamic range to a corresponding digital signal, comprising:

• a peak tracker circuit for monitoring the sensed analog signal and providing a reference potential with an amplitude corresponding to a sensed peak amplitude of the sensed analog signal;
• a level shifter circuit having an input for receiving the sensed analog signal and an output for providing a shifted analog signal, the shifted analog signal having the dynamic range of the sensed analog signal shifted in response to the reference potential;
• an analog to digital converter having an analog signal input for receiving the shifted analog signal and a reference input for receiving a signal corresponding to the reference potential and a digital output for converting the shifted analog signal to a digital signal based on a relationship between the shifted analog signal and the reference input signal;
• and
• a control circuit, responsive to the occurrence of a preselected event, for causing the peak tracker circuit to provide the reference potential with an amplitude corresponding to a sensed first peak amplitude of the sensed analog signal, the sensed first peak amplitude being the peak amplitude sensed first in time following each preselected event so that the analog to digital converter converts the shifted analog signals following each sensed first peak amplitude relative to the provided reference potential.

An apparatus for converting a sensed analog signal having a time varying amplitude within a dynamic range to a corresponding digital signal, comprising:

• a peak tracker circuit for monitoring the sensed analog signal and providing a reference potential with an amplitude corresponding to a sensed peak amplitude of the sensed analog including:
• a tracking circuit having an enabled condition for providing the reference potential with an amplitude corresponding to the amplitude of the sensed analog signal and a disabled condition for maintaining the reference potential at its amplitude at the time of disablement;
• and
• a peak detector circuit for determining when the sensed analog signal has reached a peak amplitude;
• an analog to digital converter having an analog signal input and a reference input for receiving a signal corresponding to the reference potential and a digital output for converting the analog signal to a digital signal based on a relationship between the analog signal and the reference input signal;
• and
• a control circuit, responsive to the occurrence of a preselected event, for causing the peak tracker circuit to provide the reference potential with an amplitude corresponding to a sensed first peak amplitude of the sensed analog signal, the sensed first peak amplitude being the peak amplitude sensed first in time following each preselected event so that the analog to digital converter converts the input analog signals sensed following each sensed first peak amplitude relative to the provided reference potential corresponding to said sensed first peak amplitude;
• wherein the control circuit disables the tracking circuit in response to the detection of a peak analog signal so that the reference potential corresponds to the peak analog amplitude, and enables the tracking circuit in response to each preselected event.

A method for converting an analog signal having a time varying amplitude in a dynamic range to a digital signal using an analog to digital converter having a digital output ranging from zero to full scale comprising:

• (a) sensing the amplitude of the analog signal;
• (b) determining the occurrence of a preselected event;
• (c) detecting a first peak amplitude of the sensed analog signal following the occurrence of a preselected event;
• (d) providing a reference potential corresponding to the detected first peak amplitude;
• (e) shifting the dynamic range of the sensed analog signal in response to the reference potential;
• (f) converting the shifted analog signal sensed following the occurrence of a preselected event to a digital signal based on a relationship between the analog signal and the reference potential;
• and
• (g) repeating steps (c), (d), (e), and (f) in response to each occurrence of a detected preselected event.