Pulse shaping maybe used, for example, so that the processor can implement the same detection algorithms to detect return pulses off a target and the test pulses. The processor may issue a sequence of pulses to shape the test current pulse. The processor may control the duration of the voltage pulse to shape the amplitude of the test current pulse. In an embodiment, the control signal is a voltage pulse that is produced in response to a logic signal from the processor. The processor processes the voltage signal produced by the test current signal to provide a measure of the health or characteristics of the parasitic capacitor as a proxy for the health or characteristics of the photodiode. This time-varying voltage signal is coupled through the parasitic capacitor between the photodiode's anode and cathode to induce a test current signal at the photodiode's cathode. The switch is responsive to a control signal to produce a time-varying voltage signal that is coupled through the circuit element into the photodiode's bias network. In an embodiment, a BIT circuit comprises a solid-state switch and a circuit element such as a capacitor or transformer. The transimpedance stage converts the test current signal to a test voltage signal that is supplied to the processor to evaluate the health or characteristics of the photodiode. This signal is coupled through the parasitic capacitance to induce a test current signal at the photodiode's anode. To perform the ΒΓΓ, a time-varying voltage signal such as a pulse is applied at the photodiode's anode. A processor processes the voltage signals from one or more photodiodes to evaluate characteristics of the A transimpedance stage converts the photocurrent signal to a voltage signal. Under normal operating conditions, the photoconductive photodiode responds to incident photons from a target by generating a photocurrent signal at its cathode. A failure or degradation of the photodiode manifests as a similar failure or degradation of the parasitic capacitance. This is accomplished by using the health or characteristics of the photodiode's parasitic capacitance as a "proxy" for the health or characteristics of the photodiode itself. G01R31/2635- Testing light-emitting diodes, laser diodes or photodiodes.G01R31/2632- Circuits therefor for testing diodes.G01R31/26- Testing of individual semiconductor devices.G01R31/00- Arrangements for testing electric properties Arrangements for locating electric faults Arrangements for electrical testing characterised by what is being tested not provided for elsewhere.G01R- MEASURING ELECTRIC VARIABLES MEASURING MAGNETIC VARIABLES.
Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.) Filing date Publication date Application filed by Raytheon Co filed Critical Raytheon Co Publication of EP2564222A1 publication Critical patent/EP2564222A1/en Application granted granted Critical Publication of EP2564222B1 publication Critical patent/EP2564222B1/en Status Active legal-status Critical Current Anticipated expiration legal-status Critical Links Original Assignee Raytheon Co Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.) Kuehn Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) Granted Application number EP11709821A Other languages German ( de) Google Patents Photoconductive photodiode built-in test (bit) Google Patents EP2564222A1 - Photoconductive photodiode built-in test (bit) EP2564222A1 - Photoconductive photodiode built-in test (bit)
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