Method and apparatus for measuring electrical noise in devices
AssigneeLucent Technologies Inc.
InventorSamuel Suresh Martin
Life of this patent
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Abstract
A method and apparatus for measuring electrical noise in devices is disclosed that comprises two distinct measurement phases. In one phase, the differential output resistance, r.sub.ab, between a first terminal, a, and a second terminal, b, of the device under test is measured. In the second phase, a voltage, V.sub.L (t), is measured across a load resistance, R.sub.L, that is in series with the first terminal, a, of the device under test. Then the output voltage noise spectral density, S.sub.VL, is determined based on a fourier transform of the voltage, V.sub.L (t); and the output current noise spectral density, S.sub.ia, is determined based on the output voltage noise spectral density, S.sub.VL, the load resistance, R.sub.L, and the differential output resistance, r.sub.ab.
Claims12
A method of measuring an output current noise spectral density, S.sub.ia, in a device that has at least a first terminal, a, and a second terminal, b, said method comprising the steps of:
- measuring a differential output resistance, r.sub.ab, between said first terminal, a, and said second terminal, b, of said device;
- measuring a voltage, V.sub.L (t), across a load resistance, R.sub.L, that is in series with said first terminal;
- determining an output voltage noise spectral density, S.sub.VL, based on a fourier transform of said voltage, V.sub.L (t);
- and
- determining said output current noise spectral density, S.sub.ia, based on said output voltage noise spectral density, S.sub.VL, said load resistance, R.sub.L, and said differential output resistance, r.sub.ab.
An apparatus for measuring an output current noise spectral density, S.sub.ia, in a device that has at least a first terminal, a, and a second terminal, b, said apparatus comprising:
- an A/D converter for measuring a differential output resistance, r.sub.ab, between said first terminal, a, and said second terminal, b, of said device, and for measuring a voltage, V.sub.L (t), across a load resistance, R.sub.L, that is in series with said first terminal;
- and
- a processor for determining an output voltage noise spectral density, S.sub.VL, based on a fourier transform of said voltage, V.sub.L (t), and determining said output current noise spectral density, S.sub.ia, based on said output voltage noise spectral density, S.sub.VL, said load resistance, R.sub.L, and said differential output resistance, r.sub.ab.
A method of quality control for semiconductor wafers by measuring an output current noise spectral density, S.sub.ia, in a device that has at least a first terminal, a, and a second terminal, b, said method comprising the steps of:
- fabricating a first semiconductor wafer containing said device in accordance with a first process;
- measuring a differential output resistance, r.sub.ab, between said first terminal, a, and said second terminal, b, of said device;
- measuring a voltage, V.sub.L (t), across a load resistance, R.sub.L, that is in series with said first terminal;
- determining an output voltage noise spectral density, S.sub.VL, based on a fourier transform of said voltage, V.sub.L (t);
- determining said output current noise spectral density, S.sub.ia, based on said output voltage noise spectral density, S.sub.VL, said load resistance, R.sub.L, and said differential output resistance, r.sub.ab ;
- modifying said first process based on said output current noise spectral density, S.sub.ia, to create a second process;
- and
- fabricating said second semiconductor wafer in accordance with said second process.
An apparatus that measures an output current noise spectral density, S.sub.ia, in a device that has at least a first terminal, a, and a second terminal, b, said apparatus comprising:
- means for measuring a differential output resistance, r.sub.ab, between said first terminal, a, and said second terminal, b, of said device;
- means for measuring a voltage, V.sub.L (t), across a load resistance, R.sub.L, that is in series with said first terminal;
- means for determining an output voltage noise spectral density, S.sub.VL, based on a fourier transform of said voltage, V.sub.L (t);
- and
- means for determining said output current noise spectral density, S.sub.ia, based on said output voltage noise spectral density, S.sub.VL, said load resistance, R.sub.L, and said differential output resistance, r.sub.ab.
Dependencies are inferred from the claim text.