A 33.6-dB Gain V-Band Driving Amplifier Using Half-Shielded Transformer

This letter presents a high-gain driving amplifier (DA) in 40-nm CMOS using half-shielded transformer (HSTF). The HSTF provides enhanced design flexibility and improved performance because of its adjustable half-shielded thick metal layer. To achieve efficient and accurate impedance matching, a matching model of HSTF is proposed. This model incorporates cross-coupling capacitors to capture electric-coupling between coils and utilizes series impedances to precisely represent the gate-level input impedances of transistors. Importantly, the proposed matching model is also applicable to conventional transformers. The measured DA demonstrates a 3-dB small-signal bandwidth of 12.3% from 57 to 64.5 GHz and a saturated output power of 12.2 dBm at 59 GHz. Last but not least, it achieves a power gain of 33.6 dB. To the best of the author’s knowledge, this is the highest power gain among published V-band CMOS DAs.