Harmonic Tuners are impedance tuners which allow tuning impedances at harmonic frequencies independently.
Whereas "harmonic tuning" can be obtained using wideband tuners behind frequency Diplexers or Triplexers, it is
Focus which has created the true harmonic tuners:
•In 1998 Focus introduced the PHT (Programmable Harmonic Tuner), which uses exchangeable resonators to generate high Γ(2Fo) and/or Γ(3Fo) over 360° phase rotation (US patent 6,297,649); this product is discontinued.
•In 2004 Focus invented the Multi-Harmonic Tuner - MPT-MHT which represents the breakthrough in Tuner Technology of the last 10 years (US patent 7,135,941, filed March 2004).
MPT allows pre-matching and harmonic tuning in Hybrid Active Injection Load Pull (HAILP).
HAILP is the solution for getting all the benefits of a passive and an active Load Pull systems in one setup. Active Load Pull is the only method that allows reaching the low internal impedance of power transistors, especially on wafer and at very high frequencies.
So far, the new Focus Microwaves HAILP system (Hybrid Active Injection Load Pull) is the active system that offers the best combination of performance, accuracy and cost. The system relies on the basic concept of using prematch electromechanical tuners for taking the impedance seen by the DUT closer to its conjugate output impedance, then complementing with active injection, the system can tune impedances anywhere in the Smith chart and beyond (г ≥ 1). The measurements themselves are travelling wavebased, performed using one of the following analyzers: Agilent’s PNA-X or Rohde and Schwarz’s ZVA. With the introduction of prematch tuners, the amplitude of the feedback injection signal stays within reasonable values. In traditional active systems, the power amplifier has to produce tremendous power for compensating for the strong mismatch between the injected signal and the DUT, taking the cost of the system to the roof and reducing its frequency range.
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