Aji Mattamana

Mixed-Signal SoCs With In Situ Self-Healing Circuitry

This article discusses the goals and recent achievements of the HEALICs program. The programs aim is to enhance wireless systems with sensors, actuators, and mixed-signal control loops in order to improve their performance yield.

A −189 dBc/Hz FOM T wide tuning range Ka-band VCO using tunable negative capacitance and inductance redistribution

An ultra wideband LC voltage-controlled oscillator (LC-VCO) operating in the Ka-band with equally spaced sub-band coarse tuning characteristics is proposed and characterized. A tunable negative capacitance (TNC) circuit technique is used to cancel the fixed capacitance in the LC-tank to extend the tuning range (TR). A digitally-switched varactor coarse tuning structure with an inductance redistribution technique is utilized to reduce VCO gain (KV) and retain uniform spacing between tuning curves. The proposed VCO structure and a baseline VCO are fabricated in a 130 nm CMOS process. Compared to the reference VCO, the proposed VCO achieves a 34% increase in TR with maximum KV of 450 MHz/V. The measured worst-case phase noise is -100.1 dBc/Hz at 1 MHz offset across the TR from 30.5 GHz to 39.6 GHz. The power dissipation of the VCO core is 11 mW from a 1.2 V supply. The TNC-based VCO achieves a FOMT of -189 dBc/Hz, which is the highest reported at the Ka-band.

Frequency Tuning Range Extension in LC-VCOs Using Negative-Capacitance Circuits

We present an experimentally validated capacitance cancellation structure to increase the tuning range (TR) of LC voltage-controlled oscillators (VCOs) with minimal phase noise or power impact. The cancellation is based on an ultrawideband differential active negative-capacitance (NC) circuit. An NC scheme suitable for bottom-biased VCOs is analyzed and combined with a CMOS VCO to cancel the fixed capacitance in the LC tank. The NC structure is further modified to be tunable, enabling additional expansion of the VCO TR. By manipulating the quality factor (Q) of the NC tuning varactor pair, a prototype VCO achieves a maximum TR of 27% in a 130-nm technology, while dissipating 13 mA from a 0.9-V supply. The TR is the highest reported at Q-band, covering from 34.5 GHz to 45.4 GHz. Compared to the reference VCO without an NC circuit, the TR is increased by 38%. The measured worst case phase noise is -95 dBc/Hz at 1-MHz offset, and the FOMT is -184.9 dBc/Hz.

Design of Wide Tuning-Range mm-Wave VCOs Using Negative Capacitance

Negative capacitance (NC) circuits of single-ended and differential topologies are presented, analyzed and characterized. The novel NC designs extend the bandwidth of conventional NC circuits while maintaining low power consumption. To compare the performance of the designs, a figure of merit (FOM) is proposed. A power and area efficient NC scheme employing a 130 nm CMOS technology is applied to a mm-wave LC Voltage Controlled Oscillator (LC-VCO) for demonstration. The VCO tuning range is extended by employing the NC circuit to cancel the parasitic capacitance of the LC-tank; resulting in a 35% tuning range increase as compared to the reference LC-VCO circuit. The NC-based LC-VCO achieved a 27% tuning range in the Q-Band, which is the highest reported. Measured results compare closely to the theoretical analysis of the LC-VCO operating from 34.5-45.4 GHz.

An indium phosphide X-band class-E power MMIC with 40% bandwidth

A broadband, high efficiency, X-band power amplifier is presented in this paper. The single-stage amplifier is based on indium phosphide (InP) double heterojunction bipolar transistor (DHBT) technology. In order to obtain high efficiency operation, a switch mode, class-E amplifier topology was selected. Special attention has been paid to providing the required fundamental matching conditions, as well as appropriate harmonic terminations, over the frequency band of interest. As a result, the amplifier obtained a bandwidth of 40%, with 45-60% PAE, 19-21.5dBm Pout, and 9-11.5dB large-signal gain at X-band. To the best of our knowledge, this circuit demonstrates the widest bandwidth for a class-E amplifier at X-band.

Analytical and Experimental Study of Wide Tuning Range mm-Wave CMOS LC-VCOs

The unprecedented interest in high bandwidth applications in the mm-wave range has set off a wave of research exploring techniques that enable wide tuning range voltage-controlled oscillators (VCOs). Low frequency CMOS LC-VCOs ( <;10 GHz) have been well studied in the literature and several approaches have been developed to optimize their performance. However, there lie several interesting challenges in the mm-wave space, specifically close to the fT/fmax, that motivate the need for analyzing the tuning range and phase noise in mm-wave VCOs. This paper presents a detailed analysis of the ultimate performance bound in simultaneously achieving low phase noise and wide tuning range in CMOS VCOs. The analysis is conducted on a 130 nm CMOS process, and confirmed by measurement results on three VCOs at 26 GHz, 34 GHz and 40 GHz. Finally, the impact of CMOS technology scaling (from 130 nm down to 45 nm), on the achievable performance bounds is analyzed and presented.

RF filters in SiGe BiCMOS technology and fully depleted silicon-on-insulator CMOS technology

This paper presents two integrated non-reflective bandpass filters. The filters are implemented in a silicon germanium (SiGe) BiCMOS technology and fully depleted silicon on insulator (FDSOI) CMOS technology. The purpose of these circuits is to explore the feasibility of passive filter applications on silicon substrates while maintaining low insertion loss and 50 Ohm impedance matching. The SiGe-based filter achieved 3.3-4.2 dB insertion loss across 3.5-4.5 GHz with input return loss better than -10 dB from 1-10 GHz. The FDSOI filter simulation yielded an insertion loss of 4.5 dB across the design frequency of 3.7-4.3 GHz

Digital beamforming using highly integrated receiver-on-chip modules

This paper describes the demonstration of a four-channel digital beamforming system incorporating highly integrated silicon germanium downconverter modules. The downconverter modules are designed to translate X-band frequencies (9 to 10.5 GHz) down to a common 1.0 GHz IF output. The modules were integrated with an X-band antenna array and high-speed digitizer system to form a rudimentary digital beamforming subsystem. Data was collected in a compact antenna range and compared to simulated antenna patterns. Basic calibration and beamforming methods were applied to showcase the ability to include new, highly integrated components into digital beamforming subsystem demonstrations.

X-Band Receiver Front-End Chip in Silicon Germanium Technology

This paper reports a demonstration of X-band receiver RF front-end components and the integrated chipset implemented in 0.18 mum silicon germanium (SiGe) technology. The system architecture consists of a single down conversion from X-band at the input to S-band at the intermediate frequency (IF) output. The microwave monolithic integrated circuit (MMIC) includes an X-band low noise amplifier, lead-lag splitter, balanced amplifiers, double balanced mixer, absorptive filter, and an IF amplifier. The integrated chip achieved greater than 30 dB of gain and less than 6 dB of noise figure.

A Wide-Band Complementary Digital Driver for Pulse Modulated Single-Ended and Differential S/C Bands Class-E PAs in 130 nm GaAs Technology

Wide-band digital drivers are indispensable for SMPAs (Switched Mode Power Amplifiers) in PWM (Pulse Width Modulation) and PPM (Pulse Position Modulation) applications. This paper presents the design of a wideband RF pre-amplifying buffer, innovated for very low dropout and low power complementary operation in heterojunction technologies affording only depletion type devices. A simple, passive bias level shifting technique is also incorporated to facilitate interfacing the digital modulator in silicon substrate with the PA in III-V wafer. In order to experimentally validate the concepts, the proposed driver is employed for driving an S-band single-ended class-E PA as well as for its differential version, modified to switch over S and C bands, in 130 nm GaAs pHEMT technology. The output powers of the differential amplifier are combined using on-chip transformer balun. Test results of both chips demonstrate that the implemented drivers consume less than 4% of the overall PA efficiencies, wherein the buffer responds linearly to the wideband input pulses when tested alone.