This paper presents the design of a wideband and high-linearity $E$ -band transmitter integrated in a 55-nm SiGe BiCMOS technology. It consists of a double-balanced bipolar ring mixer which upconverts a 16–21-GHz IF signal to the 71–76- and 81–86-GHz bands by the use of a 55/65-GHz local oscillator signal, followed by a broadband power amplifier which employs 2-way output power combining using an integrated low-loss balun transformer. The transmitter exhibits an average conversion gain of 24 dB and 22 dB at the 71–76- and 81–86-GHz bands, respectively, with an output 1-dB compression point greater than 14 and 11.5 dBm at each band. A maximum output power of 16.8 dBm is measured at 71 GHz. The dc power consumption is 575 mW. The presented transmitter is used to demonstrate the transmission of a 10.12-Gb/s 64 quadrature amplitude modulated signal with a spectral efficiency of 5.06 bit/s/Hz, which makes it suitable for use in future high-capacity backhaul and fronthaul point-to-point links.

This paper addresses the estimation and compensation of I/Q imbalance, one of the most prominent impairments found in wideband zero-intermediate frequency transceivers (TRxs). The I/Q imbalance encountered in this kind of TRx comprises not only frequency-selective gain and phase imbalance but also delay imbalance. Unless appropriate compensation is applied, the I/Q imbalance significantly degrades the performance of a communication system. This paper presents a novel compensation technique for transmitter I/Q imbalance based on built-in-self-calibration, a low cost and robust compensation technique that enables manufacturing as well as in-field calibration with low computational complexity. The method's performance is evaluated in a TRx with 64-quadratic-amplitude modulation and 2 GHz of bandwidth implemented with real hardware. The measurements show that the proposed technique achieves an image rejection ratio greater than 35 dB in the entire 2 GHz bandwidth and an error vector magnitude lower than 3%.

Changes in ambient temperature or chip temperature result in variations in the in-phase and quadrature (I/Q) gain and phase imbalance. As a consequence, the overall system performance can be seriously degraded, especially in wideband multi-Gb/s systems, where the I/Q imbalance is highly selective in frequency. Unless appropriately considered, temperature drifts can decrease the image rejection ratio (IRR) of the transmitter. This article presents a novel compensation method for temperature-dependent transmitter I/Q imbalance over the entire temperature range. It consists of a simple predistortion technique that, based on a few factory characterizations of gain and phase imbalance, is able to estimate and correct the I/Q imbalance at any temperature, without interrupting the normal functionality of the system. The proposed method is assessed in a 2-GHz, 64-QAM transceiver implemented with real hardware. The measurements show that the proposed approach is able to keep the IRR greater than 35 dB in the entire bandwidth and an error vector magnitude (EVM) lower than 3% over a temperature range of 70 °C.

This paper presents a high-performance frequency-domain chipless RFID reader with vector background subtraction capabilities, implemented in a software defined radio (SDR) for the first time. The proposed reader is low-cost, compact size and versatile. It is implemented in a USRP N210 paired to a modified CBX-40 daughterboard, enabling magnitude and phase data acquisition in a monostatic (one antenna) set up. The reader can perform a vector background subtraction operation between two complex measurements (with and without a chipless tag) to suppress the self-interference (SI) that hinders the response of the tag and provide 40 dB of dynamic range. To demonstrate the performance of the reader, the spectral signatures of 3 frequency-coded tags with 4 resonant frequencies are captured over the 1.5 GHz to 4 GHz band scanned with 10 MHz resolution in 251 ms, obtaining comparable measurements to those of an expensive laboratory vector network analyzer (VNA) from 20 cm to 40 cm. The detected resonant frequency offset between both devices is Δfr ≤ 4.18%. It is also demonstrated that the proposed reader can track a resonant frequency shift and therefore be used in real-time sensing applications.

This letter presents a 15-21 GHz I/Q upconverter, based on two Gilbert-cell mixers with an on-chip wideband linearization loop that extends the linear region and allows power efficient operation at backoff power levels. A quadrature LO signal is generated using an integrated two-stage polyphase filter. Measurements show a conversion gain of -5.5 dB, an output 1-dB compression point of $0$ dBm, and an image suppression of 40 dB over the 6-GHz output bandwidth. An error vector magnitude of 3.5$%$ is obtained for a 10-Gb/s 64-QAM signal with a bandwidth of 2 GHz. The circuit is integrated in a 55-nm BiCMOS process and occupies 1.07 $mm^2$. The dc power consumption is 61 mW.

This paper presents the design of an energy- efficient E-Band full-duplex transceiver for backhaul links of the future mobile networks. The link is designed to achieve 10Gbps using 2GHz channels and 64-QAM modulation. The effect of the transmitter linearity on the system performance is analyzed, showing that the required power back-off is around 10dB. A 15GHz mixer to be used in the I/Q upconverter of the transmitter is also presented, which is integrated in a SiGe 55nm process from STMicroeletronics. Measurement results show input and output bandwidths of 0-4GHz and 11.2-18GHz respectively, with a CG of 2.5dB, an OCP1dB of 0dBm and a DC power consumption of 68mW. The mixer features better linearity than other reported upconverters integrated in Si-based technologies.