280-GHz Frequency Multiplier Chains in 250-nm InP HBT Technology

We report 280 GHz 8:1 and 16:1 frequency multipliers in 250-nm indium phosphide (InP) HBT technology. The 8:1 multiplier uses three cascaded push-push emitter-coupled-pairs serving as balanced frequency doublers, with 1:1 transformers at 35, 70, and 140 GHz providing single-ended to differential conversion; the 16:1 multiplier has an additional input emitter-coupled push-push doubler whose drive signal is generated by a transistor differential input stage. With −2 dBm input power, the 8:1 multiplier generates −0.6 dBm output power at 280 and has 48-GHz 3-dB bandwidth. Spurious harmonics are suppressed by >28 dBc over the 3-dB bandwidth. With −13 dBm input power, the 16:1 multiplier generates −0.6 dBm output power at 280 and has 44-GHz 3-dB bandwidth. Spurious harmonics are suppressed by >26 dBc over the 3-dB bandwidth. The 8:1 and 16:1 multipliers consume 102- and 162-mW dc power and occupy 0.4- and 0.75-mm2 die area, respectively. To the authors’ knowledge, these results demonstrate record spectral purity for frequency multiplier chains operating near 280 GHz.