Trans-impedance amplifier with increased dynamic range

A non-transitory computer-readable medium with computer code instruction stored thereon, the computer code instructions, when executed by an a processor, cause an apparatus to:

• sample a first voltage from a first trans-impedance amplifier, the first voltage being a function of a first input current to the first trans-impedance amplifier;
• sample a second voltage from a second trans-impedance amplifier, the second voltage being a function of a second input current to the second trans-impedance amplifier;
• determine a first ratio of the first voltage to a feedback resistance associated with the first trans-impedance amplifier;
• determine a second ratio of the second voltage to a feedback resistance associated with the second trans-impedance amplifier;
• and
• add the first ratio and the second ratio to produce an estimate of a source current consisting of the first input current and the second input current;
• the first trans-impedance amplifier configured to receive a first input current and produce a first voltage as a function of the first input current, the first trans-impedance amplifier characterized by a first saturation current at which the first trans-impedance amplifier ceases to produce the first voltage as a linear function of the first input current, and the first trans-impedance amplifier having a first gain characteristic;
• the second trans-impedance amplifier configured to receive a second input current and produce a second voltage as a function of the second input current, the second trans-impedance amplifier characterized by a second saturation current at which the second trans-impedance amplifier ceases to produce the second voltage as a linear function of the second input current, and the second trans-impedance amplifier having a second gain characteristic;
• and
• the first trans-impedance amplifier and the second trans-impedance amplifier being coupled to a current steering element configured to:
• cause the first input current to flow from a current source to the first trans-impedance amplifier until the first input current reaches a first threshold current that is less than the first saturation current;
• and
• when the first input current reaches the first threshold current, cause the second input current to flow from the current source to the second trans-impedance amplifier until the second input current reaches a second threshold current that is less than the second saturation current, the second input current being current from the current source that exceeds the first threshold current.

A non-transitory computer-readable medium with computer code instruction stored thereon, the computer code instructions, when executed by an a processor, cause an apparatus to:

• sample a first voltage from a first trans-impedance amplifier, the first voltage being a function of a first input current to the first trans-impedance amplifier;
• sample a second voltage from a second trans-impedance amplifier, the second voltage being a function of a second input current to the second trans-impedance amplifier;
• determine a first ratio of the first voltage to a feedback resistance associated with the first trans-impedance amplifier;
• determine a second ratio of the second voltage to a feedback resistance associated with the second trans-impedance amplifier;
• add the first ratio and the second ratio to produce an estimate of a source current consisting of the first input current and the second input current;
• and
• digitize, using an analog-to-digital converter (ADC), the first voltage to produce a first digitized voltage, and to digitize the second voltage to produce a second digitized voltage.