RF Circuit Synthesis Tools | Qucs-S S-parameter Viewer Documentation

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# RF Circuit Synthesis Tools

## Introduction

- Filters
- Matching networks
- Power combining/splitting circuits
- Attenuators

RF synthesis tools widget

## Design Tools

### Filter Design

The following RF and MW filters can be synthesized:

Topology | Response type | Notes
--- | --- | ---
Lumped LC filters - Canonical | LPF / HPF / BPF / BSF |
Lumped LC filters - Elliptic | LPF / HPF / BPF / BSF |
Lumped LC filters - Direct-coupled (BPF) | BPF |
Stepped-Z | LPF |
Quarter-wavelength | BPF / BSF |
Capacitively-coupled shunt resonators | BPF |
Side-coupled | BPF |
End-coupled | BPF |
Semilumped | LPF / HPF |

Learn more

### Matching Networks

Single-port and two-port matching networks can be synthesized. The load can be entered manually or loaded from a Touchstone file. The following topologies are available:

Topology | Elements | Bandwidth | Complex Loads | Adjustable
--- | --- | --- | --- | ---
L-section | 2 lumped | Narrow (5-10%) | Yes | No
Single-stub | 1 TL + stub | Moderate (10-20%) | Yes | No
Double-stub | 1 TL + 2 stubs | Moderate (10-20%) | Yes | Yes
Multisection λ/4 | N×λ/4 TL | Broad (40-80%) | Real only | No
Cascaded LC | 2N lumped | Moderate (20-40%) | Real only | No
λ/8 + λ/4 | 2 TL sections | Moderate (10-20%) | Yes | No
Tee | 3 Lumped Elements | Narrow | Yes | Yes
Pi | 3 Lumped Elements | Narrow | Yes | Yes
Tapped-C | 3 Lumped Elements | Narrow | No | Yes
Tapped-L | 3 Lumped Elements | Narrow | No | Yes
Double Tapped Resonator | 4 Lumped Elements | Narrow | No | Yes

### Power combining

This tool allows to synthesize a number of power splitters/combiners and couplers

Topology | Outputs | Power Split | Isolation | Bandwidth | Notes
--- | --- | --- | --- | --- | ---
Wilkinson | 2 | Equal/Unequal | Excellent | Medium | Most common, simple
Multistage Wilkinson | 2ⁿ | Equal | Excellent | Wide | Cascaded 2-way stages
T-Junction | 2 | Equal/Unequal | None | Narrowband | Simplest, reactive
Branch-line | 2 | Equal/Unequal | Good | Medium | 90° phase, quadrature hybrid
Double-box Branchline | 2 | Equal/Unequal | Better | Medium | Improved branch-line
Bagley | N | Equal | Good | Narrowband | Multi-way, planar
Gysel | 2 | Equal | Excellent | Medium | High power, grounded resistors
Lim-Eom | 2 | Equal | Excellent | Wide | Wideband improvement
3-way Improved Isolation | 3 | Equal | Excellent | Medium | Enhanced 3-port isolation
Recombinant 3-way Wilkinson | 3 | Equal | Excellent | Medium | Alternative 3-port design
Wye Resistive Combiner | N | Equal | Depends on # outputs | Very broadband | Lossy
Delta Resistive Combiner | 2 | Equal | 6 dB | Very broadband | Lossy
Adams Resistive Combiner | 2 | Unequal | Very poor | Very broadband | Lossy

### Attenuator design

Topology | Notes
--- | ---
Pi | Matched
Tee | Matched
Bridged-Tee | Matched
Reflection attenuator | Matched
Quarter-wavelength series | Frequency-dependent. Output port unmatched
Quarter-wavelength shunt | Frequency-dependent. Output port unmatched
L-pad 1st series | Very broadband matching
L-pad 1st shunt | Very broadband matching
Series resistor | Two ports unmatched
Shunt resistor | Two ports unmatched

## See Also

- RF Engineering Calculators

RF Engineering Calculators