Photo-diode emulator circuit for transimpedance amplifier testing

An optical range finder comprising:

• an integrated circuit (IC) device that includes a die, the die including:
• a transimpedance amplifier (TIA),
• a photodiode emulation circuitry configured to:
• receive one or more parameters specifying one or more characteristics of a test current signal to be provided to the TIA,
• generate the test current signal in accordance with the one or more parameters, and
• provide the test current signal to the TIA,
• wherein the photodiode emulation circuitry includes:
• a reference current generator configured to generate a reference current,
• a digitally controlled oscillator configured to generate a first voltage signal as a periodic signal comprising a plurality of pulses, where the one or more characteristics include a pulse period and the digitally controlled oscillator is configured to ensure that a pulse period of the first voltage signal is in accordance with the pulse period specified by the one or more parameters,
• a digitally controlled pulse generator configured to generate a second voltage signal based on the first voltage signal, where the one or more characteristics include a pulse width and the digitally controlled oscillator is configured to ensure that a pulse width of the second voltage signal is in accordance with the pulse width specified by the one or more parameters,
• a digitally controlled rise/fall time generator configured to generate a third voltage signal based on the second voltage signal and on the reference current, where the one or more characteristics include a rise time and a fall time of the plurality of pulses and the digitally controlled rise/fall time generator is configured to ensure that a rise time and a fall time of the third voltage signal is in accordance with the rise time and the fall time specified by the one or more parameters, and
• a current generator configured to generate the test current signal based on the third voltage signal.