Low Loss Lumped Element Isolator Using Gyrator Circuit With Two Asymmetrical Electrodes

Abstract

The equations of the insertion loss and the isolation bandwidth of low loss two-port isolator were derived from equivalent circuit using perturbation theory. The equations show that the insertion loss gets lower in proportion to the ratio of inductors of two electrodes, while the isolation bandwidth gets narrower nearly in the proportion to the ratio.A 3.2X2.5X1.4mm3 cellular phone isolator which volume was 44% of the conventional products was realized using two electrodes of asymmetrical structure that inductance of one was much larger than that of the another.

2.45 GHz Active Isolator based on asymmetric coupler

“…A LDMOS BLC2425M10 240 transistor manufactured by Ampleon was used in the amplifier. The high design accuracy of the amplifier and asymmetric coupler using EM-circuit cosimulation at the operating frequency was verified in the previous studies [14,21]. Figure 4 shows the Sparameter results when the amplifier is biased at the drain voltage of 13.5 V and gate voltage of 1.85 V. The input and output return losses at the operating frequency of 2.45 GHz are simulated to be 10.3 and 30 dB, respectively.…”

“…Active isolators based on a symmetric hybrid coupler and an amplifier with less than unit voltage gain have been proposed for high isolation with the decrease of both the instability and the power consumption. However, the power handling capability of the isolator cannot be improved because of the power limit at the input of the amplifier [14].…”

Low-profile broadband Core-Isolator for multi-band module

“…Based on a low loss lumped element isolator using gyrator circuit [1][2][3], the equations for the insertion loss and isolation bandwidth are derived from equivalent circuit using the perturbation theory [4]. As a result of the analysis, the isolation bandwidth can get wider in relation to the ratio of inductor and capacitor of resonant elements.…”

“…CIRCUIT STRUCTURE AND ANALYSIS Figure 1 shows the equivalent circuit of broadband two-port isolator [5]. For expanding the isolation bandwidth, resonant elements of L 3 and C 3 are added to R arm in series configuration, compared with original two-port lumped element isolator using gyrator circuit [3]. The inductor L 1 and L 2 are magnetically coupled each other through the ferrite core.…”

Directly coupled lumped element isolator with three windings

“…Recently, a different circuit, a directly coupled isolator was reported by Hasegawa et al [2] [3]. As shown in Fig.1, this structure has two windings around a ferrite disk.…”