Saad Qayyum

High dynamic-range and sensitivity six-port receiver using reactive matching technique

Six-port receivers have increasingly become popular due to their simple design, wide bandwidth and low power consumption. Large area and narrow dynamic range are the key factors in limiting the use of six-port topology in commercial mobile communication devices. In order to improve its dynamic range, we propose an L-type reactive matching network for the detector stage of the six-port receiver. The proposed six-port receiver covers the frequency band from 1 GHz to 3.3 GHz. Over the specified band, it has an EVM of less than 4 % with -20 dBm of RF input power and 15 dBm of LO power. At 2.2 GHz, it has 64 dB of dynamic range with EVM between 0.33 % and 10.5 %.

Wideband six-port receiver using elliptical microstrip-slot directional couplers

A prototype of a wideband six-port receiver is presented. It consists of three multilayer elliptical microstrip-slot directional couplers (MSDCs), a power divider and reactive-matching power detectors. To compose the receiver using MSDCs, a controlled-impedance via is required. The via, taken advantage of the multilayer structure, reaches a bandwidth of more than 190% and low insertion loss. 64-QAM signals with different data rates are fed for testing. From 0.5 GHz to 5 GHz the measured EVM is less than 4% with 1 Mbps data rate. The operation frequency covers many commercial standards and thus, the concept is suitable for cognitive radio application. A sensitivity of -52dBm and -58dBm is achieved at 0.9 GHz and 2.4 GHz, respectively, without LNAs.

Wideband, high data-rate, six-port direct-conversion receiver with improved output matching and sensitivity

A wideband, six-port, direct-conversion receiver operating between 0.9 GHz and 5 GHz is presented. It employs distributed power detectors that achieve good matching up to 4 GHz and more than twice the sensitivity as compared to a resistive-matching detector. Comparison of the proposed receiver to one employing resistive-matching detectors, is also presented. The proposed design is able to deliver comparably higher data-rates for a given EVM. Alternately, it provides better EVM for the same data-rate. Measurement results demonstrate the successful demodulation of a 200 Mbps, 16 QAM signal operating at a carrier-frequency of 2.4 GHz.

Wideband ring-hybrid with quadrature-phase outputs for high-power applications

This paper presents a 3-dB coupler providing 90° output phase-difference over wider bandwidth compared to other single-stage planar couplers. The proposed design is suited for the applications where high power RF signals need to be combined with quadrature phase. It uses a symmetric rat-race coupler to achieve wider bandwidth as compared to its asymmetric counterparts. The proposed coupler has a measured peak-to-peak phase-deviation of 16° and a magnitude-imbalance of lower than 0.5 dB over the entire bandwidth spanning 2 GHz to 3 GHz. The measurement results comparing the proposed coupler with a) a branch-line coupler, b) a rat-race coupler employing a Schiffman phase-shifter and c) a Wilkinson power-divider cascaded with the Schiffman phase-shifter, are also presented.

0.8 mW, 0.1–110 GHz RF power detector with 6 GHz video bandwidth for multigigabit software defined radios

This work presents two compact, low power, broad-band and high sensitivity CMOS power detectors targeted for multi-gigabit software defined radio applications. A high sensitivity and a video detector are implemented in standard 65 nm CMOS technology with resistive input matching. Both designs have a measured input matching bandwidth up to 110 GHz. Measured peak detection sensitivity of the high sensitivity detector is 67 dB whereas the video detector possesses more than 10 GHz video bandwidth (verified up to 6 GHz through measurements). The DC power consumption of the high sensitivity detector and the video detector is 0.029 mW and 0.8 mW, respectively. To the best knowledge of the authors, the proposed designs demonstrate the widest reported input matching bandwidth while possessing a compact footprint, wide video bandwidth and high detection sensitivity in standard CMOS technology.

Efficient 2–16 GHz flat-gain stacked distributed power amplifier in 0.13μm CMOS using uniform distributed topology

This work presents the design and implementation of a flat-gain, efficient and wideband stacked distributed power amplifier (SDPA) in 0.13um CMOS technology. To obtain high output swing along with a reasonable gain, a four-transistor stack is utilized in four sections. Voltage alignment at the drain of each device in the stack is obtained by allowing a small AC swing at the gate due to voltage division between gate-source capacitance, Cgs and the external gate capacitor. Interstage matching is performed through peaking inductors. Further, the uniform distributed amplifier topology is adopted to control the impedance at each current injecting node from the stack to the artificial drain lines resulting into flat gain. Measured results show at least 10 ± 0.3dB small-signal gain from 2 −16 GHz. The SDPA demonstrated a saturated output power of 18 dBm with peak efficiency of 17% and an OIP3 of 22 dBm occupying an area of 0.83 mm2.

0.01 GHz to 110 GHz distributed common-gate power detector in standard CMOS 65 nm technology

A broadband distributed common-gate power detector (D-CGPD) is demonstrated in the paper. The D-CGPD consists of finite-ground CPWs and nMOSFETs biased in the resistive regime, which consumes no quiescent current. With the distributed configuration, measured sensitivity of 700.8 mV/mW and 68 mV/mW is obtained at 0.01 GHz and 110 GHz, respectively. Measured Su is below −15 dB for entire band. A standalone CGPD which has the same transconductance as the D-CGPD is implemented for comparison. According to the experimental verification, the D-CGPD reaches the highest sensitivity at 110 GHz under matching condition. To the best of our knowledge, this is the first D-CGPD reported in CMOS technology.

High sensitivity tunable power detector

A high sensitivity tunable power detector is proposed in the paper. An input matching network is necessary in a power detector to obtain suitable input reflection coefficient and reasonable sensitivity. A resistive- or reactive-type network is usually employed for wideband or high sensitivity purpose, respectively. However, it implies a trade-off between bandwidth and sensitivity. In order to simultaneously achieve high sensitivity and reflection coefficient, a tunable matching network, composed of a single hyperabrupt junction varactor, is investigated to realize the tunable power detector. The measurements show that the S11 below -10 dB is from 1.36 GHz to 3.36 GHz and the voltage sensitivity at 1.4 GHz, 2.4 GHz and 3.3 GHz is 903 mV/mW, 3579 mV/mW and 2646 mV/mW, respectively, with the corresponding tuning voltage.