A design methodology for the 60 GHz CMOS power amplifier using on‐chip transformers

Abstract

Due to insufficient stability of the four-channel system, some measurements were taken in a simplified system with only two MIMO channels. The numbers of transmitting lasers and receiving channels were reduced to two, and 4 Â 4 couplers/splitters were replaced with 2 Â 2 elements, but otherwise the system was similar to that presented in Figure 2. The 2 Â 2 system operated much more stable than 4 Â 4 setup, and its tuning was far more easier. In this two-channel system, we measured the influence of the carrier frequency selection on the quality of the received signals expressed by Q parameter. This relation for both channels is shown in Figure 5 for carrier frequencies in the range of 0.5-1 GHz. It is readily seen that the carrier frequency only weakly affects the received signals quality (Q parameter) over the measured range. It is worth mentioning that this range was well above the 3 dB base-band width, which was around 150 MHz in this case. This is consistent with the results of Ref. 8, where it was indicated that channel SNR is relatively immune to the carrier changes. This occurs despite the fact that the frequency transfer function between ports has a character typical for SCM transmission with pass-bands separated by dips (see example in Fig. 6). The relative immunity of SNR/eye pattern/Q parameter to the carrier frequency selection is due to fact that at the frequency response dips, the phase of the frequency response varies significantly decorrelating the elements of the matrix [h ij ] and compensating at least partially for the greater signal attenuation.Obviously, any practical realization of MIMO transmission should involve an automatic algorithm for the transmission matrix inversion. In this work, this operation was performed manually, which turned out to be very cumbersome for four-channel system. CONCLUSIONSABSTRACT: This letter presents a design methodology for the millimeter wave amplifier using 90-nm Taiwan Semiconductor Manufacture Company (TSMC) CMOS technology. The proposed design scheme with mathematically modeled transmission lines and interstage matching transformers illustrates how to design a millimeter amplifier considered in the maximum power transfer. The single-ended transformer-coupled CMOS PA is implemented to verify the design methodology. The design consists of neutralized common source (CS) amplifiers, matching transmission lines, and 3D modeled transformers. The designed circuit shows 16.2-dB gain and 9-dBm saturation power over 60-GHz channel. The measured results are well matched with the proposed modeling results.

60 GHz CMOS gain‐boosted LNA with transformer feedbacked neutraliser

“…On‐chip micro‐strip transmission lines (MSTLs) are used to design both the input and output matching networks as well as the source degeneration inductor ( L S1 – L S3 ) which makes the input matching easy. The MSTL modelling and the fundamental matching methodology depicted in [5] are applied in this Letter. The main drawback of neutralisation is the increased quality factor of the amplifier because of the positive feedback of the neutralised mechanism.…”