amplifierimpedancematchingtechnique.ppt

中華大學電機系 田慶誠 Amplifier Impedance Matching Technique RF Amplifier Block Diagram Thevening’s Equivalent RF Source Maximum Power Transfer from Source Incident Power of RF Source Incident Voltage (V+) and Current (I+) Waves Superposition of Voltages and Currents Impedance, ZIN v.s. Voltage Reflection Coefficient, G Physical Phenomenon of Standing Wave Standing Wave Pattern Voltage Standing Wave Ratio, VSWR Power Reflection and Transmission Return Loss Mismatch Factor and Mismatch Loss Questions 已知放大器輸入端的VSWR=2.0，若在輸入端將P+=0dBm入射功率送入， 請計算 Answers |G1|=|S11|= (2.0-1)/(2.0+1)= 1/3 S11(dB)= 20log(1/3)= -9.54dB RL1= 9.54dB Pr= 0dBm – 9.54dB= -9.54dBm ML1= -10log(1-(1/3)2)= 0.51dB PL= 0dBm- 0.51dB= -0.51dBm Insertion Loss For a two-port network Power Dissipation For a passive network Insertion Gain For an amplifier circuit Impedances and Reflection Coefficientsin an Amplifier Circuit Input and Output VSWR of Amplifier Source Impedance ZS and Reflection Coefficient GS Input Impedance ZIN andInput Reflection Coefficient GIN 常見錯誤觀念（一） Load Impedance ZL andReflection Coefficient GL Output Impedance ZOUT andOutput Reflection Coefficient GOUT 常見錯誤觀念（二） Power Transfer Between Two Complex Impedance Network Complex Conjugate Matching forMaximum Power Transfer 改變ZIN=RIN+jXIN，當PIN為最大值時應滿足 Power Available from Source, PAVS Reflection Coefficient Between Two Complex Impedance Network Reflection Coefficient Between Two Complex Impedance Network Reflection Coefficient Between Two Complex Impedance Network When ZIN=ZS* then G=0 由此驗證complex conjugate matching的物理意義即為讓電路無反射情形發生且形成最大功率傳輸。 (b) 若ZS是實阻抗，可得一般常見的公式： Gain Matching Technique for High Gain Amplifier Design 找到(GMS, GML)滿足gain matching conditions: GMS=GIN* and GML=GOUT* Noise Matching Technique for Low Noise Amplifier Design 找到(GS, GL)滿足noise matching conditions: GS=GOPT and GL=GOUT* Power Matching Technique forPower Amplifier Design 找到(GS, GL)滿足power matching conditions: GS=GIN* and GL=GOPT Impedance Matching Manipulation