Cisco Technology, Inc.

Sanjay Sunder

Craig S Appel

Joseph V Pampanin

Kadaba Lakshmikumar

Romesh Kumar Nandwana

Peter C Metz

Alexander Christopher Kurylak

Prajwal M Kasturi

Techniques for testing connectivity between a first integrated circuit (IC) and a second IC of an electronics package are described. An example technique involves controlling a switch(es) in the first IC to configure a bias direction of a photodiode of the second IC to forward biased. A connectivity test between the first and second ICs is performed, when the photodiode is forward biased. Another technique involves controlling a switch(es) in the first IC to configure a bias direction of a photodiode in the second IC to reverse biased. A first voltage is measured at an input of a transimpedance amplifier (TIA) in the first IC when the photodiode is reverse biased. The switch(es) are controlled to change the bias direction of the photodiode to forward biased. A second voltage is measured at the input of the TIA when the photodiode is forward biased.

Enhanced direct current (DC) built-in-self-test (BIST) coverage for optical engines and advanced packaging

An integrated circuit includes a transimpedance amplifier and an injection circuit. The injection circuit generates a first electrical test signal and injects the first electrical test signal into the transimpedance amplifier. The first electrical test signal or an output of the transimpedance amplifier generated based on the first electrical test signal is used to determine whether the integrated circuit is faulty.

Fault detection in integrated circuits

Embodiments provide for a tunable driving circuit by monitoring a frequency of a ring oscillator of an electrical integrated circuit connected to an optical modulator to determine operational characteristics of the electrical integrated circuit; setting, based on the operational characteristics, a driving voltage for a plurality of tunable inverters and a plurality of fixed gain inverters that control the optical modulator, wherein each tunable inverter of the plurality of tunable inverters is connected in parallel with a corresponding fixed gain inverter of the plurality of fixed gain inverters on one of a first arm and a second arm connected to the optical modulator; and setting an amplification strength for the plurality of tunable inverters based on the operational characteristics.

Tunable driver

The fault detection system described provides an efficient method to test and monitor component to component connectivity in an electronic package using on chip test circuits and on chip components, which reduces the need for external testing equipment and analysis. The on chip nature allows for both real time testing in the assembly process of the electronic packages and during use of the electronic package by determining an on chip reference measurement and using the reference measurement to determine an operational status of the package.

Connectivity verification for flip-chip and advanced packaging technologies

Thermal tuning and quadrature control of opto-electronic devices using active extinction ratio tracking is proved by phase shifting, via a first phase shifter, a first optical signal carried on a first arm of an interferometer relative to a second optical signal carried on a second arm of the interferometer; combining the first optical signal with the second optical signal as an output signal; detecting a peak value in the output signal; and adjusting a relative phase offset imparted by the first phase shifter on the first optical signal relative to the second optical signal, based on the peak value, to increase an amplitude of the peak value. In various embodiments, the peak value is increased over time to maximize an extinction ratio of the optoelectronic device and maintain the extinction ratio in a maximized state during operation.

Thermal tuning and quadrature control using active extinction ratio tracking

Active relative intensity noise mitigation in nested interferometers using trans-impedance amplifiers is provided by splitting an optical carrier signal into a first version and a second version, wherein the first version is orthogonal to the second version; re-combining predefined portions of the first version and the second version to determine a noise level; modulating at least one of the first version and the second version based on the noise level to reduce the noise level; after modulating the at least one of the first version and the second version based on the noise level, encoding data onto at least one of the first version and the second version; and recombining the first version and the second version to transmit the data.

Growing community of inventors

Allentown, PA, United States of America

Sanjay Sunder