A GaAs high-power RF single-pole double-throw switch IC for digital mobile communication system

Much effort has been devoted to integrate the receiving/transmitting switch since time divided multiple access (TDMA) became widely used for digital mobile communication systems. Conventional Si pin-diode switches require increased current bias as the transmit power is increased to maintain the ON state. A recently-developed GaAs monolithic switch IC can be operated with nearly zero power dissipation. However, there is distortion of the waveform as the transmit power is increased. This limits the power handling capability. Another disadvantage of the GaAs switch IC is that negative voltages are needed to control the ON and OFF states. The high-power GaAs monolithic RF switch IC reported here handles over 5W (PldB: 37dBm) with insertion loss less than 1.0 dB using a circuit to feed forward the signal to the control gate. Positive voltage switching is achieved by integrating large coupling capacitors using high dielectric material, barium strontium titanate (BST), at inputs and outputs. The RF single-pole double-throw (SPDT) switch IC is mounted in an SSO10 package, where better than 25 dB isolation is achieved at a frequency of 1 GHz.<>