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发表于 2006-8-30 22:21:00
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系列二 10. Two equal amplitude tones have a power of +10 dBm, and generate a pair of equal amplitude 3rd-order intermodulation products at -20 dBm. What is the 2-tone, 3rd-order intercept point (IP3) of the system?
b) +25 dBm
2-tone, 3rd-order intermod products increase 3 dB in power for every 1 dB increase in tones that produce them. That means the intermods increase in power at a rate of 2 dB per 1 dB relative to the tone power. The 2-tone, 3rd-order intercept point is defined as the theoretical point where the two original tones and the two 3-rd-order products would have equal power (not possible in real systems due to saturation limits).
If the two original tones have a power of +10 dBm and the 3rd-order products have a power of -20 dBm, then the intercept point will be at +10 dBm + [(+10) - (-20)]/2 dB = +10 dBm + 15 dB = +25 dBm.
好像题目不清楚哦,
按这个解释,默认了系统增益为0dB
否则应该是25+0.5*Gain[/COLOR] |
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