Electronic devices with ambient flicker detection

A folding capacitive transimpedance amplifier circuit, comprising:

• a photodiode configured to generate charge in response to ambient light;
• an integrating capacitor that receives the generated charge;
• a folding circuit coupled to the integrating capacitor, wherein the folding circuit is configured to complete a fold into the integrating capacitor to reduce the generated charge on the integrating capacitor when the generated charge exceeds a threshold voltage;
• an analog to digital converter configured to convert the generated charge and produce an output voltage;
• a timing and logic unit coupled to the analog to digital converter and the folding circuit;
• and
• a comparator that receives the generated charge from the integrating capacitor and compares the generated charge to the threshold voltage, wherein the timing and logic unit is configured to receive a signal from the comparator, and wherein the timing and logic unit is configured to clock the analog to digital converter and the folding circuit based on the signal from the comparator.

A folding capacitive transimpedance amplifier circuit, comprising:

• a photodiode configured to generate charge in response to ambient light;
• an integrating capacitor that receives the generated charge;
• a low pass filter configured to receive and filter the generated charge;
• a folding circuit coupled to the integrating capacitor, wherein the folding circuit is configured to complete a fold into the integrating capacitor to reduce the generated charge on the integrating capacitor when the generated charge exceeds a threshold voltage;
• a timing and logic unit coupled to the low pass filter and the folding circuit;
• and
• a comparator that receives the generated charge from the integrating capacitor and compares the generated charge to the threshold voltage, wherein the timing and logic unit is configured to receive a signal from the comparator, and wherein the timing and logic unit is configured to clock the low pass filter and the folding circuit based on the signal from the comparator.