Time filter

Source Type

Carlsbad, CA, United States

Gupta S.,University of Washington | Gupta S.,MaxLinear Inc. | Gangopadhyay D.,University of Washington | Gangopadhyay D.,Marvell Semiconductor Inc. | And 3 more authors.
IEEE Journal of Solid-State Circuits | Year: 2012

A reconfigurable bandpass continuous-time $\Sigma \Delta$ RF ADC tunable over the 0.8-2 GHz frequency range is presented. System- and circuit-level innovations provide low power consumption and reduced circuit complexity. The proposed architecture operates in both the first- and second-Nyquist zones to enable a wide tuning range from a fixed sampling frequency of 3.2 GHz. A fully-integrated on-chip quadrature phase-locked loop (QPLL) allows quadrature phase synchronization between a raised-cosine DAC and a quantizer. Implemented in 0.13 $\mu$m CMOS the fully-integrated prototype achieves SNDR values of 50 dB, 46 dB, and 40 dB over a 1 MHz bandwidth at 796.5 MHz, 1.001 GHz and 1.924 GHz carrier frequencies, respectively, with a total power consumption of 41 mW. The measured phase noise of the QPLL is -113 dBc/Hz at an offset frequency of 1 MHz and the reference spur is - 74.5 dBc. The RMS period jitter is 1.38 ps at 3.2 GHz. © 2012 IEEE.

Ghosh A.,MaxLinear Inc. | Pamarti S.,University of California at Los Angeles
IEEE Journal of Solid-State Circuits | Year: 2015

Non-linear voltage-to-frequency characteristic of a voltage-controlled oscillator (VCO) severely curtails the dynamic range of analog-to-digital converters (ADCs) built with VCOs. Typical approaches to enhance the dynamic range include embedding the VCO-based ADC in a ΔΣ loop or to post-process the digital data for calibration, both of which impose significant power constraints. In contrast, in this work the VCO-based ADC is linearized through a filtered dithering technique, wherein the VCO-based ADC is used as a fine stage that processes the residue from a coarse stage in a 0-1 MASH structure. The proposed filtered dithering technique conditions the signal to the VCO input to appear as white noise thereby eliminating spurious signal content arising out of the VCO nonlinearity. The work resorts to multiple other signal processing techniques to build a high-resolution, wideband prototype, in 65 nm complementary metal-oxide semiconductor (CMOS), that achieves 10 effective number of bits (ENOB) in digitizing signals with 50 MHz bandwidth consuming 8.2 mW at a figure of merit (FoM) of 90 fJ/conv.step. © 2015 IEEE.

Yu X.,Washington State University | Yu X.,Qualcomm | Sah S.P.,Washington State University | Sah S.P.,MaxLinear Inc. | And 4 more authors.
IEEE Transactions on Microwave Theory and Techniques | Year: 2014

This paper presents a high-efficiency 60-GHz on-off keying (OOK) transmitter (TX) designed for wireless network-on-chip applications. Aiming at an intra-chip communication distance of 20 mm, the TX consists of a drive amplifier (DA), a high-speed OOK modulator, and a transformer-coupled voltage-controlled oscillator. For high efficiency, a common-source topology with a drain-to-gate neutralization technique is chosen for the DA. A detailed mathematical design methodology is derived for the neutralization technique. The bulk-driven OOK modulator employs a novel dual feedthrough cancellation technique, resulting in a 30-dB on-off ratio. Fabricated in a 65-nm bulk CMOS process, the TX consumes only 19 mW from a 1-V supply, and occupies an active area of 0.077 mm2. A maximum modulation data rate of 16 Gb/s with 0.75-dBm output power is demonstrated through measurements, which translates to a bit-energy efficiency of 1.2 pJ/bit. © 2014 IEEE.

Wang G.,Texas Tech University | Munoz-Ferreras J.-M.,University of Alcala | Gu C.,Texas Tech University | Gu C.,MaxLinear Inc. | And 2 more authors.
IEEE Transactions on Microwave Theory and Techniques | Year: 2014

This paper focuses on the exploitation of linear-frequency-modulated continuous-wave (LFMCW) radars for noncontact range tracking of vital signs, e.g., respiration. Such short-range system combines hardware simplicity and tracking precision, thus outperforming other remote-sensing approaches in the addressed biomedical scenario. A rigorous mathematical analysis of the operating principle of the LFMCW radar in the context of vital-sign monitoring, which includes the explanation of key aspects for the maintenance of coherence, is detailed. A precise phase-based range-tracking algorithm is also presented. Exhaustive simulations are carried out to confirm the suitability and robustness against clutter, noise, and multiple scatterers of the proposed radar architecture, which is subsequently implemented at the prototype level. Moreover, live data from real experiments associated to a metal plate and breathing subjects are obtained and studied. © 1963-2012 IEEE.

Vigraham B.,Columbia University | Vigraham B.,MaxLinear Inc. | Kuppambatti J.,Columbia University | Kuppambatti J.,Seamless Semiconductors Inc. | Kinget P.R.,Columbia University
IEEE Journal of Solid-State Circuits | Year: 2014

We introduce a new class of feedback amplifiers, called switched-mode operational amplifiers (SMOAs) that address voltage-swing limitations of classical feedback amplifiers in scaled CMOS technologies. By exploiting the increased timing resolution available in scaled CMOS, SMOAs encode analog signal information in the time domain and provide near-rail-to-rail output-signal swing, high output-stage efficiency and better linearity. A 4th-order, 70 MHz continuous-time active-RC Butterworth filter is presented in 65 nm CMOS to demonstrate the advantages of SMOAs. The filter consumes 25.4 mW from a 0.6 V supply and achieves 55.8 dB peak SNDR while operating at a full-scale of 873 mVppd. Thanks to SMOAs, the full-scale (73% of the 0.6 V supply voltage) and the bandwidth are respectively, a 2.5× and 6.2× improvement over other state-of-the-art low-voltage filters. © 2014 IEEE.

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