Integrated Transmitter Front-end Research Articles

A Low-Voltage CMOS Current Mode Integrated Transmitter Front-end for 2.4-GHz Wireless Communications

This paper presents a low-voltage low-power current mode transmitter front-end for 2.4 GHz wireless communication applications, which is fabricated in a chartered 0.18-mm CMOS technology. The direct up-conversion is implemented with a current mode mixer employing a novel input driver stage, which can significantly improve the linearity and consume a small amount of DC current. The driver amplifier utilizes a transimpedance amplifier as the first stage and employs an inter-stage capacitive cross-coupling technique which enhances the power conversion gain as well as high linearity. The measured results show that at 2.4GHz, the transmitter front-end provides 15.5dB of power conversion gain, output P-1dB of 3dBm, and the output-referred third-order intercept point (OIP3) of 13.8dBm, while drawing only 6 mA from the transmitter front-end under a supply voltage of 1.2 V. The chip area including testing pads is only 0.9 mm 1.1 mm. Index Terms –CMOS, up-conversion mixer, driver amplifier, transmitter, current mode, high linearity, low-power

Wideband Design of the Fully Integrated Transmitter Front-End With High Power-Added Efficiency

A novel approach to enhance power-added efficiency (PAE) bandwidth and transmitting power bandwidth of the fully integrated transmitter front-end is proposed. To obtain these characteristics, a wideband multifunctional antenna operating as an output matching load of the power transistor and harmonic tuning circuits, as well as a radiator, is designed and fully integrated with a power transistor. Therefore, the wideband direct integration between the output of the power transistor and input of the antenna can be achieved without any impedance transformers. Under the condition of PAE over 50% and transmitting power within 3 dB for the peak transmitting power at the operating band, the measured PAE bandwidth and transmitting power bandwidth are 930 MHz (from 4.9 to 5.83 GHz) and 1030 MHz (from 4.8 to 5.83 GHz), respectively. About a half size is also obtained compared with the conventional wideband class F active antenna for high PAE, and the second and third harmonic radiations of the proposed structure for the normalized peak power of the fundamental frequency are measured less than -30 and -40 dB in all directions, respectively

A novel fully integrated transmitter front-end with high power-added efficiency

A novel fully integrated transmitter front-end with a simple structure is proposed to obtain both high power-added efficiency (PAE) and a compact RF-front structure. To have all these characteristics, a novel antenna operating as a radiator, a harmonic tuning circuit, and an output matching network of the power amplifier is proposed. Therefore, the direct integration of the output of the power amplifier and antenna can be achieved without any impedance transformers. From the measured results and fabrication, it is shown that the proposed transmitter front-end provides high PAE of 67.5% and compact and integrated RF-front structure by the size reduction of 43% compared with the conventional class-F active antenna for high PAE.