Impedane measurement of chip, package, and board power supply system using pseudo impulse response
View Patent ↗A method for measuring impedance of a microprocessor chip, electronic packaging, and circuit board power supply system by generating a pseudo-impulse current having a width size in the time domain not larger than the inversion of a maximum frequency of interest and obtaining a voltage measurement in a frequency domain of the pseudo-impulse current. The mechanism of the present invention then predicts the normalized Fourier transformation of the current in the frequency domain, wherein the normalized Fourier transformation depends upon a switching charge of the pseudo-impulse current, measures the switching charge of the pseudo-impulse current, obtains a first current measurement at zero frequency using the measured switching charge, and obtains a second current measurement at a frequency of interest using the first current measurement. The mechanism of the present invention then calculates the impedance of the chip/package/board power supply system using the voltage measurement and the second current measurement.
1. A computer implemented method for measuring impedance of a chip/package/board power supply system using a pseudo-impulse response, the computer implemented method comprising:
generating a pseudo-impulse current having a width size in a time domain not larger than an inversion of a maximum frequency of interest;
obtaining a voltage measurement in a frequency domain of the pseudo-impulse current;
predicting a normalized Fourier transformation of a current in a frequency domain, wherein the normalized Fourier transformation depends upon a switching charge of the pseudo-impulse current;
measuring the switching charge of the pseudo-impulse current;
obtaining a first current measurement at zero frequency using the measured switching charge;
obtaining a second current measurement at a frequency of interest using the first current measurement; and
calculating an impedance of the chip/package/board power supply system using the voltage measurement and the second current measurement.
2. The computer implemented method of claim 1 , wherein the pseudo-impulse current is generated using a repetitive switching event.
3. The computer implemented method of claim 2 , wherein the repetitive switching event comprises a plurality of latches in a scan chain switching upon each scan of data.
4. The computer implemented method of claim 1 , wherein the pseudo-impulse current is generated using a Logic Built-in Self Test scan shift technique.
5. The computer implemented method of claim 4 , wherein the Logic Built-in Self Test scan shift technique generates the pseudo-impulse current by scanning data through a scan chain.
6. The computer implemented method of claim 1 , wherein the pseudo-impulse current is generated using clock circuitry, wherein a switch of the clock circuitry generates the pseudo-impulse current at each clock cycle edge.
7. The computer implemented method of claim 1 , wherein obtaining a voltage measurement further comprises:
using sense pairs to obtain the voltage measurement in the time domain; and
performing a Fourier transformation of the voltage measurement in the time domain to obtain a measurement for voltage in the frequency domain.
8. The computer implemented method of claim 7 , wherein the Fourier transformation is performed by an oscilloscope.
9. The computer implemented method of claim 1 , wherein measuring the switching charge of the pseudo-impulse current includes:
repeating the pseudo-impulse current; and
measuring the change in current within a particular time period.
10. The computer implemented method of claim 1 , wherein obtaining a first current measurement at zero frequency is performed using the equation:
I
(
ω
)
❘
ω
→
0
=
lim
ω
→
0
1
2
π
∫
-
∞
+
∞
I
(
t
)
*
ⅇ
-
ⅈ
ω
t
ⅆ
t
=
1
2
π
∫
-
∞
+
∞
I
(
t
)
*
(
lim
ω
→
0
ⅇ
-
ⅈω
t
)
ⅆ
t
=
1
2
π
∫
-
∞
+
∞
I
(
t
)
*
ⅆ
t
=
Q
0
2
π
where
charge
Q
o
=
∫
-
∞
+
∞
I
(
t
)
*
ⅆ
t
where I(ω) is the normalized Fourier transformation of current I(t), and switching charge Q 0 is the integration of current over time.
11. The computer implemented method of claim 1 , wherein measuring the switching charge of the pseudo-impulse current is performed using the equation:
Q 0 =ΔI*ΔT
where Q 0 is an amount of charged switched during each pseudo-impulse, ΔI is a stable state current, and ΔT is a time period between each pseudo-impulse.
12. The computer implemented method of claim 1 , wherein the frequency of interest includes frequencies between 100 kHz to 1 GHz.
13. A data processing system for measuring impedance of a chip/package/board power supply system using a pseudo-impulse response, the data processing system comprising:
a bus;
a storage device connected to the bus, wherein the storage device contains computer usable code;
at least one managed device connected to the bus;
a communications unit connected to the bus; and
a processing unit connected to the bus, wherein the processing unit executes the computer usable code to generate a pseudo-impulse current having a width size in a time domain not larger than an inversion of a maximum frequency of interest, obtain a voltage measurement in a frequency domain of the pseudo-impulse current, predict a normalized Fourier transformation of a current in a frequency domain, wherein the normalized Fourier transformation depends upon a switching charge of the pseudo-impulse current, measure the switching charge of the pseudo-impulse current, obtain a first current measurement at zero frequency using the measured switching charge, obtain a second current measurement at a frequency of interest using the first current measurement, and calculate an impedance of the chip/package/board power supply system using the voltage measurement and the second current measurement.
14. A computer program product for measuring impedance of a chip/package/board power supply system using a pseudo-impulse response, the computer program product comprising:
a computer usable medium having computer usable program code tangibly embodied thereon, the computer usable program code comprising:
computer usable program code for generating a pseudo-impulse current having a width size in a time domain not larger than an inversion of a maximum frequency of interest;
computer usable program code for obtaining a voltage measurement in a frequency domain of the pseudo-impulse current;
computer usable program code for predicting a normalized Fourier transformation of a current in a frequency domain, wherein the normalized Fourier transformation depends upon a switching charge of the pseudo-impulse current;
computer usable program code for measuring the switching charge of the pseudo-impulse current;
computer usable program code for obtaining a first current measurement at zero frequency using the measured switching charge;
computer usable program code for obtaining a second current measurement at a frequency of interest using the first current measurement; and
computer usable program code for calculating an impedance of the chip/package/board power supply system using the voltage measurement and the second current measurement.
15. The computer program product of claim 14 , wherein the pseudo-impulse current is generated using a Logic Built-in Self Test scan shift technique.
16. The computer program product of claim 15 , wherein the Logic Built-in Self Test scan shift technique generates the pseudo-impulse current by scanning data through a scan chain.
17. The computer program product of claim 14 , wherein the computer usable program code for obtaining a voltage measurement further comprises:
computer usable program code for using sense pairs to obtain the voltage measurement in the time domain; and
computer usable program code for performing a Fourier transformation of the voltage measurement in the time domain to obtain a measurement for voltage in the frequency domain.
18. The computer program product of claim 14 , wherein the computer usable program code for measuring the switching charge of the pseudo-impulse current further comprises:
computer usable program code for repeating the pseudo-impulse current; and
computer usable program code for measuring the change in current within a particular time period.
19. The computer program product of claim 14 , wherein obtaining a first current measurement at zero frequency is performed using the equation:
I
(
ω
)
❘
ω
→
0
=
lim
ω
→
0
1
2
π
∫
-
∞
+
∞
I
(
t
)
*
ⅇ
-
ⅈ
ω
t
ⅆ
t
=
1
2
π
∫
-
∞
+
∞
I
(
t
)
*
(
lim
ω
→
0
ⅇ
-
ⅈω
t
)
ⅆ
t
=
1
2
π
∫
-
∞
+
∞
I
(
t
)
*
ⅆ
t
=
Q
0
2
π
where
charge
Q
o
=
∫
-
∞
+
∞
I
(
t
)
*
ⅆ
t
where I(ω) is the normalized Fourier transformation of current I(t), and switching charge Q 0 is the integration of current over time.
20. The computer program product of claim 14 , wherein measuring the switching charge of the pseudo-impulse current is performed using the equation:
Q 0 =ΔI*ΔT
where Q 0 is an amount of charged switched during each pseudo-impulse, ΔI is a stable state current, and ΔT is a time period between each pseudo-impulse.