PA Matching circuit
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Page 7
Output Matching (2/5) Transmission Line Matching - Normal Length
Page 8
Output Matching (3/5) Matching Cap Is Close To PA
Page 9
Output Matching (4/5) Matching Cap Is Distant From PA
Page 12
Vref Peripheral CBiblioteka Baidurcuit
• Series resistor can save current, but gain response will be damp. • When Vref signal rise damp, constellation extend to outside. • When Vref signal rise over shout, constellation condense toward to center. • In practical, resistor parallel with a capacitor can make Vref signal regular.
Page 6
Output Matching (1/5)
• Not match 50 ohm!! • Power matching : When PA output match to optimal impedance, PA will get max output voltage range, means best linearity point. • The optimal impedance also called
Page 13
Page 10
Output Matching (5/5) A Real PA Output Matching Schematic
Page 11
Vcc Choke Matching
• Choke (inductor) is a matching component between stage to stage. • Bypass capacitor close to PA is necessary. • If bypass capacitor too small, may occur PA oscillate.
• Input Matching – Gain, Oscillation • Output Matching – Gain, Linearity, Flatness • Vcc Choke – Oscillation, Flatness • Vref – Gain, Current
Page 5
Input Matching
• Stable condition: |
Input
1
in|<1,
|
out|<1,
|S11|<1, |S22|<1 Output
Device
2
source
in
out
load
• Solution : input series a resistor 10~33ohm, but gain will drop 2~3dB
PA Internal Circuit Block – 3 stage
Page 1
PA Internal Circuit Block – 2 stage
Page 2
3 Gain Stages PA
Page 3
2 Gain Stages PA
Page 4
Influence Of Peripheral Matching
• Only necessary when PA oscillation occur. • Why oscillate?
In a two port network, oscillation are possible when either the input or output present a negative resistance.
Page 7
Output Matching (2/5) Transmission Line Matching - Normal Length
Page 8
Output Matching (3/5) Matching Cap Is Close To PA
Page 9
Output Matching (4/5) Matching Cap Is Distant From PA
Page 12
Vref Peripheral CBiblioteka Baidurcuit
• Series resistor can save current, but gain response will be damp. • When Vref signal rise damp, constellation extend to outside. • When Vref signal rise over shout, constellation condense toward to center. • In practical, resistor parallel with a capacitor can make Vref signal regular.
Page 6
Output Matching (1/5)
• Not match 50 ohm!! • Power matching : When PA output match to optimal impedance, PA will get max output voltage range, means best linearity point. • The optimal impedance also called
Page 13
Page 10
Output Matching (5/5) A Real PA Output Matching Schematic
Page 11
Vcc Choke Matching
• Choke (inductor) is a matching component between stage to stage. • Bypass capacitor close to PA is necessary. • If bypass capacitor too small, may occur PA oscillate.
• Input Matching – Gain, Oscillation • Output Matching – Gain, Linearity, Flatness • Vcc Choke – Oscillation, Flatness • Vref – Gain, Current
Page 5
Input Matching
• Stable condition: |
Input
1
in|<1,
|
out|<1,
|S11|<1, |S22|<1 Output
Device
2
source
in
out
load
• Solution : input series a resistor 10~33ohm, but gain will drop 2~3dB
PA Internal Circuit Block – 3 stage
Page 1
PA Internal Circuit Block – 2 stage
Page 2
3 Gain Stages PA
Page 3
2 Gain Stages PA
Page 4
Influence Of Peripheral Matching
• Only necessary when PA oscillation occur. • Why oscillate?
In a two port network, oscillation are possible when either the input or output present a negative resistance.