A 30 GHz multiplexer with 500 MHz bandwidth for digital phased-array applications

This paper presents a fully integrated multiplexer operating at 30 GHz with 500 MHz bandwidth, in a 0.25 um SiGe process to demonstrate a high frequency, high bandwidth solution for a time division multiplexing phased-array system. This multiplexer enables a four to one channel reduction by sequentially sampling between each RF channel. The measurement results show that it provides 33dB channel isolation, and -30 dB (input) and -15 dB (output) reflection coefficients regardless of the switch status. Meanwhile, to complete the system, a 4 GHz clock generator is also introduced to generate sequential control signals for the multiplexer. The measured system output spectrum shows a switched 30 GHz tone with 1 GHz sampling spacing and 25% duty-cycle, which matches the sampling theory and confirms that this design is suitable for high frequency, high bandwidth applications.