Patent ID: 9647655
Date: 2017-05-09
CPC Classifications: H03K,H04N

Claim:
1. A current to frequency converter comprising: a node configured to be coupled to a photodetector and to receive a photo-current from the photodetector; a capacitor having a first terminal and a second terminal and configured to accumulate electrical charge derived from the photo-current on the first terminal and the second terminal; a switch network configured to selectively couple one of the first terminal and the second terminal to the node; a Master-Slave (MS) Flip Flop (FF) coupled to the switch network and configured to operate the switch network to toggle which of the first terminal and the second terminal is coupled to the node based on a voltage at the node, the MS FF including: a voltage reference configured to generate a first reference voltage; and a comparator coupled to the node, the voltage reference, the enable input of the first latch, the inverted enable input of the second latch, and the MS FF, wherein the comparator is configured to compare the voltage at the node with the first reference voltage, provide an output signal at a first level to the MS FF in response to a determination that the voltage at the node exceeds the first reference voltage, and provide the output signal at a second level to the MS FF in response to a determination that the voltage at the node is less than the first reference voltage, wherein the second latch of the MS FF is configured to generate a pulse signal at its latch output based on the output signal received from the comparator, the pulse signal having a frequency corresponding to an intensity of light incident on the photodetector.