WO2000025142A1 - System for measuring noise figure of a radio frequency device - Google Patents
System for measuring noise figure of a radio frequency device Download PDFInfo
- Publication number
- WO2000025142A1 WO2000025142A1 PCT/US1999/024207 US9924207W WO0025142A1 WO 2000025142 A1 WO2000025142 A1 WO 2000025142A1 US 9924207 W US9924207 W US 9924207W WO 0025142 A1 WO0025142 A1 WO 0025142A1
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- power
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/26—Measuring noise figure; Measuring signal-to-noise ratio
Definitions
- the present invention relates in general to systems for measuring the noise figure of a radio frequency device and in particular to a system for measuring noise figure employing a randomly modulated signal as a device stimulus.
- Noise figure F a commonly used measure of the noise produced by radio frequency devices, is defined as the signal-to-noise ratio P SI /P NI of the device's input signal divided by the signal-to-noise ratio P so /P No of the device's output signal:
- An electronic device has a gain (or loss) G
- the output signal noise P N0 of any device includes a component GP NI , the amplified noise in the device's input signal, and an "added noise" component P NA generated by the device itself:
- the standard input signal noise power P NI used when measuring noise figure F is the very small noise power P 0 produced by a resistor operating at a room temperature, specifically 290 degrees Kelvin. A resistor of any size will generate the same amount of noise power.
- a resistor's noise power P N is evenly distributed over the radio frequency range and has a value in any frequency band of width B that is proportional to resistor temperature T,
- the well-known "Y-factor" method determines noise figure F in a manner that satisfies the standard definition of noise figure and yet allows us to employ test signal powers that may be larger or smaller than P 0 .
- FIG. 1 represents a radio frequency DUT 10 as an ideal (noiseless) amplifier 12 having a gain (or loss) G and a noise generator 14 producing "excess" noise power P E .
- the excess noise power is represented as being equivalent to the noise power output of a resistor at some temperature T E :
- the output of noise generator 14 drives the input of a summer 16.
- Amplifier 12 then amplifies its input signal with gain G to produce an output signal of power
- the quantity GkBT E is simply another way of expressing the added noise P NA produced by device 10.
- T E (T H -YT C )/(Y-1) [15]
- equation [18] is independent of bandwidth B . As long as the DUT output powers P HO and P co are measured over the same bandwidth, it is not necessary to know the exact bandwidth over which the measurements are taken.
- the present invention is a method and apparatus for testing noise figure F of a radio frequency device under test (DUT) .
- a radio frequency sine wave signal is randomly (or pseudo-randomly) modulated to provide a test signal for which power is distributed non-unifor ly over the radio frequency spectrum.
- Powers P HI and P CI are equivalent to the thermal noise power in bands of width B of signals produced by resistors held at differing "hot” and "cold" temperatures T H and T c , respectively.
- T H P HI /kB
- T c P CI /kB
- the test signal is applied as an input signal to the DUT and a resulting DUT output signal is processed to produce a time domain data sequence representing DUT output signal magnitude as a function of time.
- the time domain data sequence is then transformed to a frequency domain data sequence representing the power of the DUT output signal carried in successive frequency bands of width B.
- Two values of the second data sequence represent output signal powers P H0 and P co signal carried in the two frequency bands F H and F c .
- a "measured" noise figure F M is then computed as
- GAIN is the gain of the DUT and where F s is the noise figure F s of measurement system itself.
- F s the noise figure F s of measurement system itself.
- the method of the present invention is easier to implement within an automatic test equipment environment than prior art systems because it does not require the use of resistors held at particular temperatures as test signal sources .
- FIG. 1 is a block diagram modeling a radio frequency device being driven by noise produced by a resistor
- FIG. 2 illustrates in block diagram form an apparatus for measuring noise figure F of a radio frequency device under test (DUT) in accordance with the present invention
- FIG. 3 is a plot of the power density P' ⁇ of the TEST signal of FIG. 2, and
- FIG. 4 illustrates the spectrum analyzer of FIG. 2 in more detailed block diagram form.
- test signal power P 0 is defined as the power produced by a resistor at 290 degrees K within that narrow band of the radio frequency spectrum, Within any narrow band of width B in the radio frequency spectrum, a resistor held at some temperature T produces a noise signal having a power P in any part of the radio frequency spectrum of bandwidth B of
- resistor noise power P 0 produced by a resistor at 290 degrees Kelvin is relatively small and predictable, it can make a suitable standard power source when testing a radio frequency DUT for noise figure F.
- Equation [19] precisely defines F, it is not always practical to directly test a DUT for noise figure F by applying the signal produced by a resistor held at 290 degrees K as a test signal input to a DUT. Since from equation [19] the value of F depends on the quantity GP 0 , then when the gain G of the DUT is too large or too small, a test signal input of P 0 may produce an output signal power P N0 that is too large or too small to be accurately measured.
- the well-known "Y-factor" method of determining noise figure F allows us to test a DUT in a manner that satisfies the standard and yet allows us to use test signal powers that may be more suitable than P 0 .
- the Y-factor method also allows us to avoid having to measure or know the gain of the DUT.
- the DUT is stimulated with an input test signal produced by a resistor held at a known "hot" temperature T H .
- the output power P H0 of the DUT's output signal within some narrow frequency band of width B then measured.
- the DUT is also stimulated with an input test signal produced by a resistor held at a known "cold" temperature T c .
- the output power P c0 of the DUT's output signal is the measured over the same narrow frequency band.
- the noise figure F of the DUT is then computed as :
- T H and T c can be chosen so that the DUT output power levels P H0 and P HC are within ranges that are appropriate for the DUT and which can be conveniently measured.
- the Y-factor method frees us from having to use a particular test signal power level, certain aspects of the prior art Y-factor method make it less than satisfactory for use in an high-speed testing environment.
- a tester using this method would have to be able to precisely adjust the noise temperatures to two different values. Any switch that it uses to alternately connect the two noise powers to the DUT must be matched to their resistances, and the time the tester may requires to perform an output signal power level measurement for each of two different input signal levels can be lengthy.
- the Y-factor method of measuring noise figure is improved by using a randomly (or pseudo-randomly) modulated sine wave signal as a test signal input to a DUT instead of the output signals of hot and cold resistors .
- FIG. 2 illustrates in block diagram form an apparatus 20 for measuring noise figure F of a radio frequency device under test (DUT) 26 in accordance with the present invention.
- a binary phase shift keyed (BPSK) modulator circuit 22 randomly modulates a single-frequency (suitably 900 MHz) sine wave signal from a signal source 24 to produce a test signal (TEST) input to a DUT 26.
- DUT 26 amplifies its input TEST signal with a gain (or loss) of G to produce an output signal (OUTPUT) .
- a spectrum analyzer 28 processes the OUTPUT signal to produce a data sequence (DATA) input to a computer 30. Successive data elements of the DATA sequence indicate the total OUTPUT signal power included in successive bands of width B of the radio frequency spectrum.
- Computer 30 computes the noise figure F of the DUT based on the information contained in the DATA sequence and on the characteristics of the TEST signal.
- FIG. 3 is a plot of the power density P' ⁇ (in dBm/Hz) as a function of frequency for the TEST signal of FIG. 2. While the power density spectrum of the sine wave signal output of signal generator 24 has a single power spike at 900MHz, when we randomly modulate the sine wave signal output of signal generator 24, the resulting TEST signal is wideband in nature having a power density that is non-zero over a large portion of the radio frequency band. The total power P ⁇ contained in any small frequency band of width B can be determined by integrating the TEST signal frequency spectrum of FIG. 3 over that frequency band.
- total power P ⁇ for each band may be found by integrating the TEST signal power density P' ⁇ over each band.
- the total power for each band power approximately equal to 1 Hz times the power density P' ⁇ Hz at the center of the band.
- the total signal power P H is approximately -120 dBm. The same level of power would be generated by a resistor held at some "hot" temperature T H where
- the total signal power P c is approximately -130dBm, a power level equivalent to that generated by a resistor held at some "cold" temperature T c where
- successive data elements of the DATA sequence output of spectrum analyzer 28 indicate the total OUTPUT signal power included in successive bands of width B of any desired portion of the radio frequency spectrum.
- bandwidth width B chosen to be 1 Hz
- one of those DATA sequence values will indicate an output power P H0 of DUT 26 at the frequency band between 900 MHz and 900.000001 MHz.
- Another of those DATA sequence values will indicate an output power P co of DUT 26 at the frequency band between 902 MHz and 902.000001 MHz.
- Computer 30 obtains values of P H0 and P co for the two frequency bands from the DATA sequence.
- Computer 30 consults a pre-loaded lookup table for power levels of the TEST signal to select TEST signal levels P H and P c for the same two frequency bands, and then computes the noise figure F of DUT 26 using equations [21] -[25].
- the spectrum analyzer 28 of FIG. 2 produces thermal noise that adds to the noise generated by DUT 26.
- F computer 30 computes from equations [21] -[25] is somewhat smaller than the true value of F for DUT 26.
- the measurement system noise power P M generated by spectrum analyzer 28 is significant in compared to the noise power generated by DUT 26, then the value of F computed from equations [21] -[25] should be adjusted to account for the contribution to noise figure F provided by measurement system noise .
- F DOT the noise figure of DUT 26 of FIG. 2
- F M the noise figure of the analog portions of spectrum analyzer 28
- F ⁇ o ⁇ the total noise figure for the DUT and spectrum analyzer in series. It is well-known that for such series connected devices, the following relationship holds true:
- F DUT F ⁇ o ⁇ - [ ( F M - 1 ) /G] [ 27 ]
- noise figure F was computed using only two data elements from the DATA sequence output of spectrum analyzer 28, the two DATA sequence elements indicating the power carried in the two 1Hz OUTPUT signal frequency bands starting at 900 and 902 MHz.
- computer 30 could compute a noise figure F in the manner described above from DATA sequence elements corresponding to any two frequency bands for which the TEST signal has differing power levels.
- FIG. 4 illustrates a spectrum analyzer 28 of FIG. 2 in more detailed block diagram form.
- Spectrum analyzer 28 includes a down converter 40 for converting the OUTPUT signal to a signal OUTPUT' having a frequency spectrum shifted 900 MHz, a bandpass filter 42 for filtering the OUTPUT' signal to remove frequencies outside a range of interest, an analog-to-digital converter (ADC) 44 for digitizing the filtered OUTPUT' signal at a rate at least twice its highest frequency to produce and output data sequence DATA' .
- the DATA' data sequence represents the magnitude of the OUTPUT signal as a function of time over a frequency range of interest.
- a digital filter 46 implements a discrete Fourier transform such as the well-known fast Fourier transform (FFT) to convert the DATA' sequence into the output DATA sequence representing the power of the OUTPUT signal in each of a set equal-sized frequency bands within the frequency range of interest .
- FFT fast Fourier transform
- computer 30 of FIG. 2 carries out the function of filter 46, by receiving the DATA' output of ADC 44 and executing a well-known discrete Fourier transform algorithm to convert the time-domain DATA' sequence to the frequency DATA sequence .
- filter 46 a well-known discrete Fourier transform algorithm to convert the time-domain DATA' sequence to the frequency DATA sequence .
- modulator 2 is a BPSK modulator
- other types of modulators could implement modulator 22, including but not limited to, quadrature phase shift keyed (QPSK) , quadrature amplitude modulation (QAM) , frequency modulation (FM) , amplitude modulation (AM) , and vector modulations (I/Q), or any combination thereof.
- QPSK quadrature phase shift keyed
- QAM quadrature amplitude modulation
- FM frequency modulation
- AM amplitude modulation
- I/Q vector modulations
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- Testing Electric Properties And Detecting Electric Faults (AREA)
Abstract
Description
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Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP99971093A EP1125139A4 (en) | 1998-10-28 | 1999-10-25 | System for measuring noise figure of a radio frequency device |
JP2000578665A JP2002528724A (en) | 1998-10-28 | 1999-10-25 | System for measuring noise figure of radio frequency devices |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/181,940 US6114858A (en) | 1998-10-28 | 1998-10-28 | System for measuring noise figure of a radio frequency device |
US09/181,940 | 1998-10-28 |
Publications (1)
Publication Number | Publication Date |
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WO2000025142A1 true WO2000025142A1 (en) | 2000-05-04 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/US1999/024207 WO2000025142A1 (en) | 1998-10-28 | 1999-10-25 | System for measuring noise figure of a radio frequency device |
Country Status (5)
Country | Link |
---|---|
US (1) | US6114858A (en) |
EP (1) | EP1125139A4 (en) |
JP (1) | JP2002528724A (en) |
KR (1) | KR100624666B1 (en) |
WO (1) | WO2000025142A1 (en) |
Cited By (2)
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WO2007068323A1 (en) * | 2005-12-14 | 2007-06-21 | Rohde & Schwarz Gmbh & Co. Kg | Method for measuring the noise factor of a device under test by means of a network analyzer |
US8456170B2 (en) | 2008-05-09 | 2013-06-04 | Advantest Corporation | Test apparatus for digital modulated signal |
Families Citing this family (20)
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FR2789181B1 (en) * | 1999-02-01 | 2001-04-20 | St Microelectronics Sa | METHOD FOR DETERMINING THE FREQUENCY JUST NOISE OF A SOURCE AND DEVICE IMPLEMENTING THE METHOD |
US6496261B1 (en) | 1999-09-24 | 2002-12-17 | Schlumberger Technologies, Inc. | Double-pulsed optical interferometer for waveform probing of integrated circuits |
US6252222B1 (en) * | 2000-01-13 | 2001-06-26 | Schlumberger Technologies, Inc. | Differential pulsed laser beam probing of integrated circuits |
US7006939B2 (en) * | 2000-04-19 | 2006-02-28 | Georgia Tech Research Corporation | Method and apparatus for low cost signature testing for analog and RF circuits |
TW490563B (en) * | 2000-08-30 | 2002-06-11 | Ind Tech Res Inst | Regulable test integrated circuit (IC) system for signal noise and its measurement method |
US6693439B1 (en) * | 2000-09-28 | 2004-02-17 | Cadence Design Systems, Inc. | Apparatus and methods for measuring noise in a device |
JPWO2002033427A1 (en) * | 2000-10-17 | 2004-02-26 | 株式会社アドバンテスト | Noise measuring device, method, and recording medium |
US7035324B2 (en) * | 2001-08-01 | 2006-04-25 | Agilent Technologies, Inc. | Phase-noise measurement with compensation for phase noise contributed by spectrum analyzer |
US6965242B2 (en) * | 2002-06-28 | 2005-11-15 | Rohde & Schwarz Gmbh & Co. Kg | Procedure and apparatus for the determination of the noise level of an electronic object to be measured |
US20050137814A1 (en) * | 2003-12-19 | 2005-06-23 | Joseph Kelly | Method of measuring noise figure using arbitrary waveforms |
US8036616B2 (en) * | 2008-05-05 | 2011-10-11 | Infineon Technologies Ag | Noise parameter determination method |
JP5608205B2 (en) * | 2012-11-01 | 2014-10-15 | アンリツ株式会社 | measuring device |
KR101265535B1 (en) * | 2013-01-09 | 2013-05-20 | 주식회사 썬닉스 | Monitoring apparatus and method thereof |
US10120008B2 (en) * | 2013-08-29 | 2018-11-06 | Keysight Technologies, Inc. | Method and apparatus for estimating the noise introduced by a device |
US11119140B1 (en) * | 2017-08-31 | 2021-09-14 | Christos Tsironis | Impedance pattern generation for noise parameter measurement system |
CN108508287B (en) * | 2018-06-08 | 2019-12-27 | 中国电子科技集团公司第四十一研究所 | Method for measuring noise coefficient based on vector network analyzer and power meter |
US10761134B2 (en) * | 2018-10-25 | 2020-09-01 | Rohde & Schwarz Gmbh & Co. Kg | Method and measurement system for identifying the noise figure of a device under test |
CN111220858B (en) * | 2018-11-26 | 2022-04-12 | 北京华航无线电测量研究所 | Quantum Bell state detector noise equivalent power measurement method |
US11102596B2 (en) | 2019-11-19 | 2021-08-24 | Roku, Inc. | In-sync digital waveform comparison to determine pass/fail results of a device under test (DUT) |
JP7374938B2 (en) * | 2021-02-08 | 2023-11-07 | アンリツ株式会社 | Mobile terminal testing equipment and mobile terminal testing method |
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US4491783A (en) * | 1981-04-25 | 1985-01-01 | Tokyo Shibaura Denki Kabushiki Kaisha | Apparatus for measuring noise factor and available gain |
US4905308A (en) * | 1989-04-05 | 1990-02-27 | Cascade Microtech, Inc. | Noise parameter determination method |
US5191294A (en) * | 1990-04-02 | 1993-03-02 | Wiltron Company | Measuring noise figure and y-factor |
US5970429A (en) * | 1997-08-08 | 1999-10-19 | Lucent Technologies, Inc. | Method and apparatus for measuring electrical noise in devices |
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US5068615A (en) * | 1988-10-25 | 1991-11-26 | Cascade Microtech, Inc. | Noise parameter test apparatus |
-
1998
- 1998-10-28 US US09/181,940 patent/US6114858A/en not_active Expired - Lifetime
-
1999
- 1999-10-25 EP EP99971093A patent/EP1125139A4/en not_active Withdrawn
- 1999-10-25 JP JP2000578665A patent/JP2002528724A/en not_active Withdrawn
- 1999-10-25 WO PCT/US1999/024207 patent/WO2000025142A1/en active IP Right Grant
- 1999-10-25 KR KR1020017003673A patent/KR100624666B1/en not_active IP Right Cessation
Patent Citations (4)
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US4491783A (en) * | 1981-04-25 | 1985-01-01 | Tokyo Shibaura Denki Kabushiki Kaisha | Apparatus for measuring noise factor and available gain |
US4905308A (en) * | 1989-04-05 | 1990-02-27 | Cascade Microtech, Inc. | Noise parameter determination method |
US5191294A (en) * | 1990-04-02 | 1993-03-02 | Wiltron Company | Measuring noise figure and y-factor |
US5970429A (en) * | 1997-08-08 | 1999-10-19 | Lucent Technologies, Inc. | Method and apparatus for measuring electrical noise in devices |
Non-Patent Citations (1)
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2007068323A1 (en) * | 2005-12-14 | 2007-06-21 | Rohde & Schwarz Gmbh & Co. Kg | Method for measuring the noise factor of a device under test by means of a network analyzer |
US7804304B2 (en) | 2005-12-14 | 2010-09-28 | Rohde & Schwarz Gmbh & Co. Kg | Method for measuring the noise figure of a device under test with a network analyser |
US8456170B2 (en) | 2008-05-09 | 2013-06-04 | Advantest Corporation | Test apparatus for digital modulated signal |
TWI408915B (en) * | 2008-05-09 | 2013-09-11 | Advantest Corp | Test device of digital modulation signals, digital modulator, modulation method and semiconductor using the same |
Also Published As
Publication number | Publication date |
---|---|
EP1125139A1 (en) | 2001-08-22 |
KR20010075290A (en) | 2001-08-09 |
US6114858A (en) | 2000-09-05 |
EP1125139A4 (en) | 2003-09-10 |
KR100624666B1 (en) | 2006-09-18 |
JP2002528724A (en) | 2002-09-03 |
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