Successive approximation calibration apparatus, system, and method for dynamic range extender

A method of extending the dynamic range of an electrical system including a variable gain amplifier connected to an analog-to-digital converter producing an output signal of predetermined bit-width, said method comprising:

• receiving an analog signal of particular temporal magnitude;
• amplifying the received analog signal by a first gain value;
• changing said first gain value to a second gain value as a function of the temporal magnitude of the received analog signal;
• converting the analog signal into a counterpart digital signal of predetermined bit-width;
• modifying the counterpart digital signal with a selected one of predetermined offset values effective to ensure continuous linearity;
• adjusting the bit-width of the counterpart digital signal to compensate for a change in amplification provided by said variable gain amplifier;
• and
• continuously extending the dynamic range of the electrical system, without abrupt variations.

A method of extending the dynamic range of an electrical system including a variable gain amplifier connected to an analog-to-digital converter producing an output signal of predetermined bit-width, said method comprising:

• receiving an analog signal of particular temporal magnitude;
• amplifying the received analog signal by a first gain value;
• changing said first main value to a second gain value as a function of the temporal magnitude of the received analog signal;
• converting the analog signal into a counterpart digital signal of predetermined bit-width;
• modifying the counterpart digital signal with a selected one of predetermined offset values effective to ensure continuous linearity;
• adjusting the bit-width of the counterpart digital signal to compensate for a change in amplification provided by said variable gain amplifier;
• and
• producing an output digital signal indicative of whether the analog signal detected exceeds a particular one of a plurality of predetermined thresholds and applying an offset corresponding to the particular threshold.

A processing system for an imager device comprising:

• a camera system for producing an imager signal;
• a correlated double sample circuit for receiving data from an imager;
• a variable gain amplifier connected to said correlated double sample circuit, for receiving the sampled output of the correlated double sample circuit;
• an analog-to-digital converter (ADC) coupled to said variable gain amplifier;
• a shifter for holding a bit sequence of predetermined length, said shifter connected to the output of said ADC;
• and
• a control circuit coupled to the output of said correlated double sample circuit and adapted to control the amplification setting of said variable gain amplifier, and to control the shift status of bits in said shifter, as well as to apply an offset value to correct a discontinuity in the gain characteristic;
• and
• wherein said control circuit includes another analog-to-digital converter and logic circuitry for determining the values of offsets to be used in eliminating discontinuities in the gain characteristic;
• and
• wherein said another analog-to-digital converter includes a plurality of comparators connected to the output of said correlated double sampling circuit, which are used to determine offset values used to eliminate discontinuities in the gain characteristic.

A method of correcting the extension of the dynamic range of an imaging system having a correlated double sampling system, a variable gain amplifier circuit connected to said correlated double sampling system, an analog-to-digital converter connected to said variable gain amplifier circuit, and a shifter containing a predetermined number of bits greater than the digital output width of said analog-to-digital converter, said shifter connected to said analog-to-digital converter for receiving the output bit set of said analog-to-digital converter into predetermined locations in said shifter, including:

• determining the magnitude of input signals from an imaging system, which are sampled by a correlated double sampling system;
• adjusting the gain in a variable gain amplifier in a selected direction;
• determining adjustment offset values corresponding to trip points at which gain adjustments are made;
• and
• repositioning the bit set stored in said shifter in an opposite direction from the gain direction expressed upon said variable gain amplifier, to produce a digital output of greater dynamic range from said shifter than from said analog-to-digital converter.