Design Of Millimeter-wave Power Amplifier With Transformer Coupling In CMOS Processing

Millimeter wave(mm-wave) is electromagnetic wave with wavelength from 1mm~10mm. Mm-wave circuits are widely used in personal wireless communications, communications between satellites, mm-wave imaging, mm-wave radar, mm-wave guidance, biomedical, radio astronomy, security and other fields. Power amplifier as one of the most difficult parts for design in mm-wave transmitter has attracted wide attention in academia and industy. Mm-wave power amplifier designed with CMOS processing has the advantages of low cost, easy connected with digtal circuits. At the same time it also faced difficulties, such as mm-wave passive componets designing and modeling, low output power of the power amplifier in mm-wave frequencies, low power gain of the transistor in mm-wave frequencies. In order to solution these problems, the theory of mm-wave circuits designing has been in-deeply studied in this paper.A systematic method to design an on-chip transformer balun with impedance transformation in millimeter-wave integrated circuit design is presented in this paper. A way though adjusting centre tap to improve the performance of on-chip transformer balun is proposed and a V-band on-chip balun has been design with CMOS processing. A lumped model of the balun in mm-wave freqencies has been established for the V-band on-chip transformer balun. A solution for on-chip transformer balun design and modeling has been provided in this paper.And then an eight-input and two-output power combing transformer has been designed with 90 nm CMOS process. With this transformer, a Q-band power amplifier with high output power has been designed and fabracited. The measure result shows that the small signal gain of the Q-band power amplifier is 20.38 d B and the saturated output power reaches 21.08 dBm, the peak PAE reaches 14.5% at 45 GHz. It provided a reference for high output power mm-wave power amplifier designing with CMOS processing.Last, a W-band power amplifer worked in 100 GHz has been designed with 90 nm CMOS processing. The cut-off frequency of the transistor in 90 nm CMOS processing is ablout 120 GHz. It is difficult for W-band power amplifier design with low gain of the transistor around 100 GHz and high loss of the passive components in W-band. A way thouth coupling the signals between the drain and gate of the transistor with transformer has been proposed to improve the gain of the circuit with the no efficiency and linearity performance worsended. The simulation result shows that the gain of the circuit has been improved 2dB with this transformer. The simulation result presents that the small signal gain of the W-band power amplifier is 14.8 dB and the saturated output power reaches 10.34 dBm, the peak PAE reaches 4.5% at 100 GHz. It provided a reference to improve the gain of the transistor in CMOS processing at the frequency in mm-wave, especially around the cut-off frequency fT.