Single stub and double stub matching using smith chart pdf

Sometimes when all paths look equal, you just have to shoot from the hip and pick one. Some circuits may result in more reasonable component values. Sometimes matching components can be used as dc blocks (capacitors) or to provide bias currents (inductors).

How does one choose? There are a number of popular reasons for choosing one over another. The figure shows what matching networks will work in which regions. In any particular region on the Smith chart, several matching circuits will work and others will not. пЃпЂ Matching Network Types: L-/T-/пЃ°-section Networks пЃ® L-section Networks (Two-component ): Lumped elements: L/C C * At high freq., capacitance is like Short-cirucited 2 X sc / Z 0 * Factors in the selection of matching networks - complexity -bandwidth requirement (such as broadband design) - adjustability - implementation (transmission line, chip R/L/C elements. Minimum power loss in the feed line & maximum power delivery linearizing the frequency response of the circuit improving the S/N ratio of the system for sensitive receiver components (lownoise amplifier, etc.) reducing amplitude & phase errors in a power distribution network (such as antenna array-feed network) Z in Reflection coefficien t (or Return Loss) : пЃ‡in (or S11 ) пЂЅ ( Z in пЂ Z 0 ) /( Z in пЂ« Z 0 ) Impedance matching (or tuning) is important for the following reasons : incident (or input) Microstrp Single-Stub and Double-Stub Tuning Quarter-Wave Transformer * The Bode-Fano Criteria Matching with Lumped Elements - L Network - T & пЃ° Networks - Lumped Elements for MIC : Chip R, L, C. Tuning using the Optimization Assistant yielded a value of Delta = -31.633 mil.CHAPTER 5 Impedance Matching and Smith Chart * Pozar MW (Ch 5), вЂњImpedance Matching and TuningвЂќ * Pozar RF (Ch 2), вЂњItransmission Lines & Microwave NetworksвЂќ *Ludwig, (Ch 3, Ch 8), вЂњMatching and Biasing NetworksвЂќ *Rogers, (Ch 4), вЂњRadio Frequency Integrated Circuit DesignвЂќ ExampleДЄ double-stub matching network was designed to match a load impedance of 100 - j30 Ohms to a 50 Ohm line at a center frequency of 5 GHz with open circuited stubs. Pozar, Microwave Engineering, 2nd Edition, John Wiley & Sons: New York, 1998, pp. Refer to Design Assistant.ДЇor a more detailed discussion of this device, see: D. A SmartComponent subnetwork is empty until the Design Assistant is used to generate the design.The optimization minimizes the value of S11 (referenced to the conjugate of Zin) at the design center frequency by changing the length of the stubs.The output port termination is set to Zload. The input port termination is set to the conjugate of Zin so that the ideal input reflection coefficient will be zero.For example, if stub 1 is open circuited, the solution for which stub 1 must realize a capacitive reactance is chosen. Since two solutions are possible, the solution that results in the smallest length of stub 1 is chosen.MTEE component width constraint violations will be avoided generally by choosing similar characteristic impedances for the line, stub, and feed.

However, if this will not realize the match, the length of line is computed such that the rotated circle on the Smith chart encloses the load admittance.

The length of the line between the stubs is nominally chosen to be an eighth of a line wavelength.

Zfeed1 and Zfeed2 are used simply to ensure that the input and output legs of the microstrip tee components are of the proper width.

An impedance match can be realized using any combination of stub types, although some combinations can be more realizable.

A double-stub matching network matches a complex load impedance (Zload) to a desired complex input impedance (Zin) using two shunt stubs and a connecting line.

Length added to stubs for tuning performance Characteristic impedance of stub line 1 (nearest input)Д¬haracteristic impedance of stub line 2 (nearest output)Д¬haracteristic impedance of line between stubsД¬haracteristic impedance of line connected to port 1Д¬haracteristic impedance of line connected to port 2

Single stub and double stub matching using smith chart pdf