Impedance Matching (1)

Smith Chart Construction (The center line represents an axis where X=0.) (+) (-)

z L =1±j

Adding a Series Capacitance to an Impedance

Adding an Inductor in Series Insertion of a series inductor to an impedance moves the impedance upward, causing a rotation clockwise along a constant circle of resistance

Series Inductance Neg L High LLow L fixed frequency Insertion of a series inductor to an impedance moves the impedance upward, causing a rotation clockwise along a constant circle of resistance

Adding a Capacitor in Series Insertion of a series capacitor to an impedance move impedance downward, causes a rotation counter clockwise along a constant circle of resistance

Series Capacitance High C Low L Neg C fixed frequency Insertion of a series capacitor to an impedance move impedance downward, causes a rotation counter clockwise along a constant circle of resistance

Admittance

Admittance Example

Method 1

Method 2 1. Find the Z. 2. Rotate Smith Chart 180 degrees

Smith Chart Construction (The center line represents an axis where X=0.) (+) (-) Conductance circle Inductive susceptance Rotate the impedance chart by 180 degrees Capacitive susceptance

Adding a Shunt Capacitance Insertion of a shunt capacitor causes a rotation clockwise along a constant circle of admittance

Adding a Shunt Capacitance High C Low C Neg C fixed frequency Insertion of a shunt capacitor causes a rotation clockwise along a constant circle of admittance

Adding a Shunt Inductance Insertion of a shunt inductor causes a rotation counter clockwise along a constant circle of admittance

Shunt Inductance Neg Ind High L Low L fixed frequency Insertion of a shunt inductor causes a rotation counter clockwise along a constant circle of admittance

WBAN Matching Example

Input impedance (100k,Cc1)

Input Admittance (100k,Cc1)

Adding a Shunt Inductance Insertion of a shunt inductor causes a rotation counter clockwise along a constant circle of admittance

Effect of Adding L1 With L1

Adding a Capacitor in Series Insertion of a series capacitor to an impedance move impedance downward, causes a rotation counter clockwise along a constant circle of resistance

Effect of C2

Adding a Shunt Capacitance Insertion of a shunt capacitor causes a rotation clockwise along a constant circle of admittance

Effect of C1

S11 at 1GHz Cc=1pF Rbias=100 k L1=40 nH C2=695 fF C1=5.5 pF