A compact broadband transformer‐based linear CMOS power amplifier design

Abstract

the isolation characteristic, as shown in Figure 6(b). Tables 1 and 2 show the measured antenna efficiencies t various gap distances and interconnection positions. As the maximum value available for h is limited to 3 mm, we chose the gap distance between two boards to be 3 mm. The results reveal that the efficiency of the proposed MIMO antenna is dependent upon the isolation between the two radiating elements.Figures 7(a)-7(f) show three-dimensional (3D) radiation patterns of the designed two radiating elements at 750, 880, and 1920 MHz, respectively. Although the laptop structure affects the radiation pattern, especially in low band, the measured radiation patterns are nearly omnidirectional over most of the frequency band. Figure 8 shows the measured antenna gain and the envelope correlation coefficient (ECC) as a function of frequency. The average gains of the two antenna elements are shown as short dashed and dashed-dotted lines, and the ECC is drawn as a solid line in Figure 8. The gain varies from~À6.7 dBi to À1.7 dBi, and the ECC is mostly lower than 0.35 across the entire bandwidth. Although the MIMO antenna is installed within an electrically small USB dongle device, the proposed internal MIMO antenna can achieve good gain and ECC performances using the two-stage ground. The mean effective gain (MEG) values vary from 0.28 to 0.47 over the entire bandwidth, as shown in Figure 9. CONCLUSIONSA compact internal MIMO antenna with a separated two-stage ground is proposed. The two radiating elements in the MIMO antenna have good performance and a wide bandwidth for wireless communications (LTE, DCN, and PCS-1900). Although the two elements are embedded in a USB dongle and operate at low frequency (LTE band), good isolation and relatively high antenna efficiency were achieved by using a two-stage ground structure. The proposed antenna is a superior candidate for future wireless applications due to its capability to fit within a USB dongle terminal. ABSTRACT: A novel broadband transformer-based CMOS power amplifier (PA) design method is studied in this article. To obtain a broadband PA, the parasitic parameters of the transformer are absorbed into the PAs load match and their impacts on bandwidth are studied. The fully-integrated PA combined with an 8-shaped transformer is implemented in 0.13 lm CMOS process with only 1.2 Â 1.2 mm 2 chip size and operates at Class AB mode. The single-stage PA delivers 27.36 dBm output power with 27% efficiency and has 10.5 dB gain. It has 500 MHz bandwidth (1 dB degeneration) in the large and small signal measurements. IMD3 and IMD5 are also lower than À25 dBc at 19 dBm across the bandwidth. The spectrum of PA can meet the m-WiMAX spectrum mask at 19 dBm average power level.

A Current-Shared Cascade Structure With an Auxiliary Power Regulator for Switching Mode RF Power Amplifiers

“…4, and are the equivalent resistance levels of the first and second driver stages, respectively. The values of according to the ratio can then be calculated as follows: (4) Given that is generally greater than 1, becomes lower than half of , and hence the effective supply voltage of the second driver stage becomes lower than half of . In spite of the increased transistor size of the second driver stage, the peak-to-peak voltage of the output of the second driver stage then decreases considerably.…”