circuit 402 first phase shift circuit 600 in fig6 includes internal phase shift signal path 602 defined by first rf blocking capacitor c 61 connected in series with inductor l 61 and second rf blocking capacitor c 62 with internal node n 61 defined between first capacitor c 61 and inductor l 61 and internal node n 62 defined between inductor l 61 and second capacitor c 62 first phase shift circuit 600 also includes pair of diodes d 61 and d 62 which have their anodes connected to ground via common node n 63 and their cathodes connected to nodes n 61 and n 62 respectively d 61 and d 62 are biased via bias resistor r 61 from the vmode control the operation of first phase shift circuit 600 is now described first phase shift circuit 600 consists of two shunt variable capacitors c 61 c 62 that were realized with reversed bias hbt base collector junctions diodes d 61 d 62 and series inductor l 61 in a high power mode both diodes are deactivated and the signal goes through c 61 l 61 and c 62 where c 61 and c 62 are shorted at rf frequencies in the low power mode both diodes are reverse biased resulting in depletion capacitors the amount of phase shift is determined by the capacitance values and the inductance values of these three components in the hp mode the vmode may assume a low voltage value e g 0v this results in a higher capacitance value of the varactor and therefore more phase shift for the network in the corresponding lp mode the vmode assumes a high voltage value e g u2267 2 85 v this results in a lower capacitance.