A 300-GHz Upconverter With 0-dBm Psat and 44-GHz Bandwidth in 130-nm SiGe BiCMOS

A 300-GHz modified Gilbert upconverter with high output power and wide bandwidth (BW) in a 130-nm SiGe BiCMOS process is presented. A low-impedance transmission line (low-
$Z_{0}$
TL) is introduced to achieve impedance matching between the mixer core and the RF/LO balun. This low-loss low-
$Z_{0}$
TL eliminates the need for lossy capacitors to ground at subterahertz frequency, thereby improving the output power and BW. The impedance transformation using the balun and low-
$Z_{0}$
TL is analyzed to achieve optimum impedance matching. A high-power
$\times 6$
frequency multiplier chain (
$\times 6$
FMC) with a
$P_{\mathrm {sat}}$
of 8–9 dBm at 230–250 GHz is utilized to provide the LO source for the upconverter, further enhancing the output power. The proposed upconverter achieves a measured peak saturated output power (
$P_{\mathrm {sat}}$
) of 0 dBm at 280 GHz with a maximum 3-dB BW of 44 GHz. The measured peak 1-dB output power of −3.6 dBm and conversion gain (CG) of −8.4 dB are obtained at 290 and 280 GHz, respectively. Moreover, to the best of our knowledge, the proposed upconverter exhibits the highest output power in silicon-based processes beyond 270 GHz.