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发表于 2009-3-28 09:37:07
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来几个RF问题，看看大家的RF基础功底——系列一
[52RD.com]
RF Quiz #1[52RD.com]
1. What is the impedance of free space?[52RD.com]
[52RD.com]
2. What happens to the noise figure of a receiver when a 10 dB attenuator is added at the input? [52RD.com]
a) Noise figure increases by 10 dB[52RD.com]
b) Noise figure decreases by 10 dB[52RD.com]
c) Noise figure doesn't change[52RD.com]
3. An RF system has a linear throughput gain of +10 dB and an output 3rd-order intercept point (OIP3) of +30 dBm. What is the input 3rd-order intercept point (IIP3)? [52RD.com]
a) +20 dBm[52RD.com]
b) +40 dBm[52RD.com]
c) +30 dBm[52RD.com]
4. Which filter type has the greatest selectivity for a given order (i.e., N=5)? [52RD.com]
a) Bessel[52RD.com]
b) Chebychev (ripple=0.1 dB)[52RD.com]
c) Butterworth[52RD.com]
5. Which mixer spurious product is a 5th-order product? [52RD.com]
a) 1*LO + 5*RF[52RD.com]
b) 6*LO - 1*RF[52RD.com]
c) 3*LO - 2*IF[52RD.com]
6. A 2.8 GHz oscillator is phase-locked to a 10 MHz reference oscillator that has a single-sided phase noise of -100 dBc at 1 kHz offset. What is the single-sided phase noise of the 2.8 GHz oscillator at 1 kHz offset? [52RD.com]
a) -48.6 dBc[52RD.com]
b) -100 dBc[52RD.com]
c) -51.1 dBc[52RD.com]
7. What is the power of a 2 Vpk-pk sine wave across a 50 ohm load? [52RD.com]
a) -20.0 dBm[52RD.com]
b) +10.0 dBm[52RD.com]
c) +19.0 dBm[52RD.com]
8. Which 2-port S-parameter is commonly referred to as "reverse isolation" in an amplifier? [52RD.com]
a) S21[52RD.com]
b) S22[52RD.com]
c) S12[52RD.com]
9. What are the minimum and maximum combined VSWR limits at an interface characterized by a 1.25:1 VSWR and a 2.00:1 VSWR? [52RD.com]
a) 1.75:1 (min), 2.25:1 (max)[52RD.com]
b) 1.60:1 (min), 2.50:1 (max)[52RD.com]
c) 0.75:1 (min), 3.25:1 (max)[52RD.com]
10. An ideal directional coupler has a directivity of 25 dB and an isolation of 40 dB. What is its coupling value? [52RD.com]
a) 65 dB[52RD.com]
b) 40 dB[52RD.com]
c) 15 dB[52RD.com]
[52RD.com]
好贴！置顶几天，大家都看看自己还有哪不足
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