RF面试一些必问的问题

* IP3
- What is IP3？ Why is it important？
- Why is it important？
- How to measure IP3？ (use a coupler to add the two input tones together)
- IIP3 vs OIP3？ (IIP3(dBm) = (A_W1,W2(dB)-A_IM3(dB))/2 +P_in(dBm), OIP3(
dBm) = (A_W1,W2(dB)-A_IM3(dB))/2 +P_out(dBm), OIP3(dBm)-IIP3(dBm) = G(dB))

* Noise Figure
- What is Noise Figure？
- What is Noise Figure of multi-stage LNA？
- How to measure Noise Figure？ (1.Noise figure meter. 2.Total gain method
. 3. Y-factor)
- Remark: F (Noise factor, linear), NF (10logF, logarithm)

* What are main parameters of LNA？ (Gain, NF, IP3, P1dB, ) How to measure
them？

* How to design a two-state LNA？ (trade-off between gain and noise figure)

* Receiver:
- The architecture of Superheterodyne Receiver.
- The architecture of Homodyne Receiver.
- Parameters of the receiver. (NF, G_t(transducer power gain), IP3 (why
is it import), )

* Matching network:
- LC component match:
- Shunt Stub transmision line:
- Try the cases: 1. 25+j25 Ohm --> 50 Ohm. 2. 50Ohm --> 25Ohm.)

* Filter: esp. 1st order HPF, LPF and BPF. What will step function be like
after LPF, HPF？

* Automatic test softwares: LabVIEW, HPV or CVI.

* Oscillator:
- Basic working theory of Oscillator.
- Phase noise.

* Spectrum Analyzer:
- Basic working theory. (first use a mixer to down-convert RF signal to
DC band.)
- What is Resolution Bandwidth？

* GSM and CDMA.

＝＝＝＝＝＝＝＝＝RF 其它问题：＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
* Transmitter architecture: Why does the transmitter not care the noise so
much？

* Modulation theory:

* PLL architecture:

* IP2: What is IP2？

* Basic statistics: Gaussian distribution.3Sigma.

Than

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