A K-band (20 GHz) monolithic amplifier was developed and fabricated by adopting a low-κ benzocyclobutene (BCB) coplanar waveguide (CPW) line and InGaP-InGaAs doped-channel HFETs (DCFETs). This monolithic microwave integrated circuit (MMIC) utilizes a high impedance BCB CPW microstrip line (Z0 = 70 Ω) for the biasing circuits, and a Z0 = 50 Ω line for the RF signal transmission. The low dielectric constant characteristic of the BCB interlayer is beneficial for a common-ground bridge process, which reduces the parasitics. The calculated loss tan δ is 0.036 for the BCB at 20 GHz. The one-stage MMIC amplifier achieves an S21 of 5 dB at 20 GHz, which is the first demonstration of the K-band InGaP-InGaAs DCFET monolithic circuit.
- Benzocyclobutene (BCB) interlayer
- Coplanar waveguide (CPW)
- Doped channel HFET (DCFET)
- K-band monolithic microwave integrated circuit (MMIC)