Alberto Valdes-Garcia

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A fully-integrated 16-element 60-GHz phased-array receiver is implemented in IBM 0.12m SiGe BiCMOS technology. The receiver employs RF-path phase-shifting and is designed for multi-Gb/s non-line of sight links in the 60-GHz ISM band (IEEE 802.15.3c and 802.11ad). Each RF front-end includes variable-gain LNAs and phase shifters with each front-end capable of(More)
Top-gated graphene transistors operating at high frequencies (gigahertz) have been fabricated and their characteristics analyzed. The measured intrinsic current gain shows an ideal 1/f frequency dependence, indicating a FET-like behavior for graphene transistors. The cutoff frequency f(T) is found to be proportional to the dc transconductance g(m) of the(More)
A phased-array transmitter (TX) for multi-Gb/s non-line-of-sight links in the four frequency channels of the IEEE 802.15.3c standard (58.32 to 64.8 GHz) is fully integrated in a 0.12m SiGe BiCMOS process. It consists of an up-conversion core followed by a 1:16 power distribution tree, 16 phase-shifting front-ends, and a digital control unit. The TX core is(More)
The demonstration of multi-Gb/s links in the 60GHz band has created new opportunities for wireless communications [1,2]. Due to the directional nature of millimeter-wave (mm-Wave) propagation, beam steering enables longer-range non-line-of-sight (NLOS) links at these frequencies. A phased-array architecture is attractive for an integrated 60GHz transmitter(More)
This paper reviews silicon millimeter-wave radio circuits operating between 60 and 100GHz. Transmitter and receiver chips operating in the 60-GHz ISM band are highlighted, where the packaged chipset has shown data rates as high as 2 Gb/s over 5m for a wireless high-definition video link. In addition, a 60GHz PA with 23dBm output power and a class-E 60GHz PA(More)
This paper presents an all-passive, 4-element, phased-array beamformer based on a differential, reflectiontype phase shifter (RTPS) operating in the 60GHz band. The RTPS consists of a differential, vertically-coupled, coupledline hybrid and variable, parallel-LC, resonant, reflective loads, both of which enable low-loss millimeter-wave operation. The design(More)
This paper introduces a 2<sup>nd</sup> harmonic extraction technique in a 46.4-58.1 GHz frequency synthesizer. The frequency doubling approach is based on tapping second harmonic signals at the VCO supply and tail nodes and amplifying them to provide a differential output. Since the amplifiers do not load the VCO outputs, neither the tuning range nor the(More)
A wafer-scale graphene circuit was demonstrated in which all circuit components, including graphene field-effect transistor and inductors, were monolithically integrated on a single silicon carbide wafer. The integrated circuit operates as a broadband radio-frequency mixer at frequencies up to 10 gigahertz. These graphene circuits exhibit outstanding(More)