Image Processing Reference
In-Depth Information
Preheating
• Replacement of execution program
• Replacement of Measurement Die
• Change of measurement clock frequency
• Change of measurement supply voltage
Supply Voltage: fix as VDD1
Clock frequency: fix as F1
Temperature of atmosphere: Ta1
Execution Program: Program A
Calibration
In-situ measurement
Supply Voltage: varied
Clock frequency: gating
Temperature of atmosphere: Ta1
Supply Voltage: fix as VDD1
Clock frequency: fix as F1
Temperature of atmosphere: Ta1
Execution Program: standby
Execution Program: Program A
• Re-selection of VMONs
Fig. 8. Procedure for in-situ measurement
as described in section2.1, since the ring oscillator oscillates asynchronously with the chip
operating frequency, high resolution can be achieved by averaging multiple low-resolution
measurements using an oscilloscope (Abramzon, et al., 2004). This method is also effective
for eliminating noise from measurements. If the wire length between VMON and VMONC is
longer, the amplitude of the signal becomes small. This small amplitude suffers from the effect
of noise. However, by using this averaging method, the influence of noise can be reduced, and
signals can be measured clearly.
3. Measurement results
The in-situ measurement scheme was implemented in a 3G cellular phone processor
(Hattori et al., 2006) as an example. Supply-noise maps for the processor were obtained while
several actual applications were running. Figure 9 shows a chip photomicrograph. Three
CPU cores and several IPs, such as an MPEG-4 accelerator, are implemented in the chip. A
general-purpose OS runs on the AP-SYS CPU, and a real-time OS runs on the APL-RT CPU.
The chip was fabricated using 90-nm, 8-Metal (7Cu+1Al), dual-Vth low-power CMOS process
technology.
This chip has 20 power domains, and seven VMONs are implemented in several of the power
domains (Kanno, et al., 2006). Five VMONs are implemented in the application part (AP-Part),
and two VMONs are implemented in the baseband part (BB-Part). VMONs 1, 3, 4, and 5 are
in the same power domain, whereas the others are in separate power domains. The reason
these four VMONs were implemented in the same power domain is that this domain is the
largest one, and many IPs are integrated in it.
