This paper proposed a rat-race circuit implement on IPD (Integrated Passive Device) process. The termination loads of the circuit have a complex impedance value. Design equations for single frequency operation of distributed structure are provided. Lumped components representation of distributed structure is illustrated in the design example. The measured results yield-5.6 dB reflection coefficient at the input port and-14 dB transmission coefficient at the isolation port. The transmission coefficients at the output ports are better than-7 dB while the phase difference is less than 2 degrees.
