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Takushi HASHIDA Yuuki ARAGA Makoto NAGATA
A diagnosis testbench of analog IP cores characterizes their coupling strengths against on-chip environmental disturbances, specifically with regard to substrate voltage variations. The testbench incorporates multi-tone digital noise generators and a precision waveform capture with multiple probing channels. A prototype test bench fabricated in a 90-nm CMOS technology demonstrates the diagnosis of substrate coupling up to 400 MHz with dynamic range of more than 60 dB. The coefficients of noise propagation as well as noise coupling on a silicon substrate are quantitatively derived for analog IP cores processed in a target technology, and further linked with noise awared EDA tooling for the successful adoption of such IP cores in SoC integration.
Yuuki ARAGA Nao UEDA Yasumasa TAKAGI Makoto NAGATA
A probing front end circuit (PFE) senses and digitizes voltage noises at in-circuit locations on such as power supply wiring and substrate taps in a chip, with the simplest circuit construction only with a source follower or a unity gain buffer, followed by a latch comparator. The PFE with 2.5V I/O transistors in a 65nm CMOS technology node demonstrates 9.0 ENOB and 60.7dB SFDR in equivalent sampling at 1.0Gs/s, for a sinusoidal waveform of 10MHz with 200mV peak-to-peak amplitude. Behavioral modeling of an entire waveform acquisition system using PFEs includes the statistical variations of reference voltage and sampling timing. The simulation quantitatively explains the measured dynamic properties of on-chip noise monitoring, such as the AC response in SNDR and digitizing throughputs, with the clear dependency on the frequency and amplitude of input waveforms.