Current generator

An apparatus, comprising:

• a voltage converter coupled to receive a reference voltage, and provide a reference current in response, wherein the voltage converter includes a plurality of trim transistors coupled to receive a respective bit of a calibration word, and wherein a level of the reference current is generated from the reference voltage in response to the number of trim transistors enabled;
• a current controlled oscillator coupled to receive the reference current and provide an oscillating signal in response, wherein a period of the oscillating signal is based on the level of the reference current;
• and
• a digital calibration coupled to receive a count indicative of a number of periods of the oscillating signal that occur during a pulse signal, and provide the calibration word in response.

An imaging system, comprising:

• an array of pixels coupled to generate image data in response to image light;
• readout circuitry coupled to receive the image data and perform one or more operations on the image data, the readout circuitry including a current generator coupled to provide a reference current, wherein the reference current provides an operating point for the one or more operations, and wherein the current generator comprises:
• a low dropout regulator (LDO) coupled to receive a reference voltage, and provide a reference current in response, wherein the LDO includes a plurality of trim transistors coupled to receive a respective bit of a calibration word, and wherein a level of the reference current is generated from the reference voltage in response to the number of trim transistors enabled;
• a current controlled oscillator coupled to receive the reference current and provide an oscillating signal in response, wherein a period of the oscillating signal is based on the level of the reference current;
• and
• a digital calibration coupled to receive a count indicative of a number of periods of the oscillating signal occurring during a pulse signal, and provide the calibration word in response.