A direct Ku-band linear subharmonically pumped BPSK and I/Q vector modulator in multilayer thin-film MCM-D

A direct Ku-band linear subharmonically pumped binary phase-shift keying (B PSK) and in-phase/quadrature (I/Q) vector modulator have been developed usi ng multilayer thin-film multichip module (MCM-D) technology. Ali passives a re integrated in the low cost MCM-D substrate. To the authors knowledge, th is is the first modulator based on thin-film integrated passive components. The subharmonic mixing is performed using a beam-lead antiparallel diode p air mounted onto the MCM using thermocompression. A custom diode model has been developed and verified using nonlinear network analyzer measurements: an excellent agreement between the measured and simulated powers and phases for more than nine harmonics is demonstrated. Additionally, it is shown th at an optimal reactive termination for the third harmonic of the local osci llator (LO) exists such that a very flat BPSK mixer conversion is obtained. This is validated by measurements that indicate a +/-0.25-dB variation on the conversion loss for an LO frequency varying from 6.8 to 7.6 GHz. The I/ Q vector modulator consists of a Wilkinson power divider, a coplanar-wavegu ide Lange coupler, and two BPSK modulators. It has a measured image rejecti on better than -27 dB over the RF range of 13.4-15.2-GHz band (correspondin g to a vector phase and amplitude error lower than 2 degrees and 1%). The i mage rejection is even better than -32 dB over the very small aperture term inal band (RF: 14-14.5 GHz).