6.6 Effect of Bond-wire Inductance

At higher frequencies when the discrete power transistors are used in hybrid power-amplifier integrated circuits, it is necessary to take into account the device output bond-wire and lead inductance. Its influence may be significant, especially in the practical cases of high output power level and low supply voltage. For instance, the effect of a bond-wire inductance for even-harmonic Class-E configuration gives unrealistically small values for the optimum load resistance and dc-feed inductance when, even at ultra-high frequencies, typical values for the bond-wire inductance of approximately. 1 nH constitute most, if not all, of the required dc-feed inductance [23].

Figure 6.15: Normalized optimum load network parameters versus normalized bondwire inductance L _b/L for parallel-circuit Class E

The exact values for the optimum load network parameters can be easily obtained from Eqs. (6.52) TO Eqs. (6.55), which were derived analytically for a generalized Class-E load network. Fig. 6.15 shows the dependencies of the normalized parallel inductance l = ?L/R, parallel capacitance c = ?CR, and load resistance r = RP _0Ut/V ² _c for a parallel-circuit Class-E mode as functions of the normalized bond-wire inductance L _b/L. From Fig. 6.15 it follows that an increasing effect of the bond-wire inductance L _b leads to significantly reduced Class-E optimum values for the load resistance R and shunt capacitance C and increased optimum value for the finite dc-feed inductance L.