US 5,296,856 A · Window tracking ADC

Abstract

A window tracking analog to digital convertor (10) and method of signal conversion is disclosed. A sample and hold amplifier (16) samples an analog input signal and passes the sampled signal to a window comparator (20). The window comparator (20) analyzes the analog input signal to determine if its amplitude falls between upper and lower reference levels which establish a tracking "window." If the amplitude of the signal falls outside of the window, a control processor (34) and window reference tracker (24) adjusts the reference levels in the direction of the reference level which was exceeded until the analog input signal falls within the window, the adjusted reference level in the direction of adjustment representing the level of the sampled signal. A continuous interval timer (38) counts the amount of time that the analog input signal remained within the window. Once the window is adjusted, a digital output signal represented by the amplitude of the sampled signal and the number of timing intervals is sent an instrument such as a computer for use.

Claims15

Dependent claims

A method of converting an analog input signal into a digital output signal, comprising the steps of:

(a) sampling an analog input signal to be converted, said analog input signal having an amplitude;
(b) comparing said amplitude of said sampled analog input signal to a voltage window defined by an upper reference voltage and a lower reference voltage;
(c) generating an out of limit signal in response to said amplitude of said sampled analog input signal falling outside said voltage window;
(d) adjusting, in response to said out of limit signal, said voltage window until said amplitude of said sampled analog input signal is within said voltage window;
(e) generating a plurality of periodic timing signals;
(f) counting said timing signals and generating a first output signal indicative of the number of timing signals occurring between said out of limit signal and an immediately preceding out of limit signal;
and
(g) generating a second output signal indicative of said adjusted voltage window, said second output signal corresponding to said amplitude of said sampled analog input signal.

5 more elements

An apparatus for converting an analog signal into digital form, comprising:

(a) signal sampling means for sampling an analog input signal to be converted, said analog signal having a voltage level;
(b) comparator means for comparing said analog input signal to a voltage window and generating an out of limit signal in response to said analog input signal having a voltage level outside said voltage window, said voltage window defined by an upper reference voltage and a lower reference voltage;
(c) reference tracker means for adjusting said voltage window until said voltage level of said analog input signal is within said window, said reference tracker means responsive to said out of limit signal;
(d) timer means for generating a plurality of periodic timing signals;
and
(e) processor means for counting the number of timing signals occurring between consecutive out of limit signals and generating a first output signal indicative thereof and for generating a second output signal indicative of said voltage level of said analog input signal.

3 more elements

Dependencies are inferred from the claim text.

Window tracking ADC

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Window tracking ADC

Life of this patent

Abstract

Claims15