1 Mixer characterization
DC input
Bias voltage
Bias Current
RF input
Lo input
IF output
2 mixer device
Schottky diode:
BJT or FET ：参考集成IC的datasheet
3 Phase Domain
4 Modulator Basics
The simplest modulators are VCOs（FM）and variable amplifier （AM）
BPSK
QPSK
