the carrier SHSN operates with equivalent circuit as (L 1 + L c 1 + L m) / (C 1 - C m) . The relationship between L1, L c1, Lm and Cc1, Cm of single SHSN at low power region can be derived as from its resonance frequency L 1 + L c1 + L m = maximum current magnitude. This leads to the disappearance of the mutual magnetic coupling inductance (L c1 + L m) and (L c2 + L m) in the SHSN. Its equivalent circuit is shown in Fig. 9. As the mutual magnetic coupling (L c1 + L m) and (L c2 + L m) disappears from back-off to saturation, the equivalent circuit of SHSNs become L 1 / (C 1 - C m) and L 2 / (C 2 - C m) . The relationship between L1 and C1, Cm for each SHSN can be derived according to its resonance frequency 1 (22) 16r 2 f 20 (C 1 - C m) At the saturation, both carrier and peaking devices are conducting. The two signals are nearly orthogonal, resulting in the RF electric current directions in the SHSNs that are opposing and alternately reaching their L1 = 1 (23) 16r 2 f 20 (C 1 - C m) Zcarrier Zcarrier Carrier Carrier L1 Mutual Coupling Network TL1 2f0 Lm 2f0 Lc 1 + L m Cm TL2 2f0 C1 - Cm Lc 2 + Lm 2f0 C 2 - Cm L2 Zpeaking Peaking Zpeaking Peaking Figure 7. Proposed second harmonic short circuited networks [32] for carrier and peaking devices. SHSN Lc 1 + Lm Lm MCN L1 Mixed Coupling L1 TL1 Lc 1 + Lm Lm MCN C1 - Cm MCN Cm Cm Lc 2 + L m C2 - Cm Lc 2 + Lm TL2 C 1 - Cm C2 - Cm SHSN L2 L2 Figure 8. Operating principle of MCN at the low power region in [32]. 54â IEEE CIRCUITS AND SYSTEMS MAGAZINE FOURTH QUARTER 2020