Modulation Mapping – identifying the different operating frequency
Scan Chain failure analysis
Laser Voltage Extraction (LVx)
LVx is a combination of image and waveform-based analytical methods comprised of two components: Laser Voltage Imaging (LVI) and Continuous Wave Laser Voltage Probing (CW-LVP). LVx enables visualization of transistor activity across a field-of-view in the frequency domain, and permits the fast acquisition of functional waveforms.
Laser Voltage Imaging (LVI)
LVI maps specific frequencies of operation to physical transistor locations. This enables rapid identification of which areas of circuitry are active at a particular frequency. The technique may be used to locate failures in scan chains, or as a methodology to determine the optimal location of a signal to be acquired using Laser Voltage Probing (LVP). As the laser is scanned across the active device, the signal analyzer amplitude of the selected frequency is plotted as an intensity signal. The image thus formed visually displays transistors which are functioning at the selected frequency. By selecting a different frequency in the analyzer, a different set of transistors operating at the newly chosen frequency will be highlighted. The highlighted transistor data from all selected frequencies may be color coded to provide a more complete picture of how the device is functioning.
Scan Chain Failure Analysis
Since LVI highlights the areas of the circuit that operate at a particular frequency, the technique lends itself well to the analysis of scan chain failures. A failing scan chain is identified through the use of test equipment. By feeding the scan chain a signal at a predetermined frequency and comparing a good device with a failing one, it is possible to locate breaks in the scan chain.
Continuous Wave Laser Voltage Probing (CW-LVP)
The same hardware used to implement LVI also makes it possible to acquire functional waveform data using Continuous Wave Laser Voltage Probing (CW-LVP). Unlike high-bandwidth pulsed-laser LVP, such as that employed in the DCG Systems Ruby instrument, this fast LVP uses a Continuous Wave (CW) laser.
The difference between CW-LVP and pulsed-laser LVP
The advantage of CW-LVP when compared to pulsed-laser LVP is the real-time sampling, which provides higher efficiency in capturing multiple samples for each trigger from the stimulus, hence shortening the acquisition time. The effective bandwidth of the system using CW-LVP is limited to approximately 7 GHz, which makes it suitable for quick functional analysis.
LVx upgrade for the EmiScope, Meridian and Ruby
- On the Meridian, LVx provides a valuable ability to perform functional analysis correlated to emission or laser stimulation data.
- On the EmiScope, CW-LVP waveforms complement the TRE histograms in order to validate timing and functional data.
- For the Ruby, LVI indicates the optimal location for the placement of the LVP probe.