Programmable Phase Research Articles

A clock and data recovery circuit with programmable multi-level phase detector characteristics and a built-in jitter monitor

We demonstrate a clock and data recovery (CDR) circuit having a new type of a multi-level bang-bang phase detector (ML-BBPD). The gain characteristics of our ML-BBPD can be programmed by scanning the dead-zone width of a variable dead-zone BBPD in the time domain. Its linear-like gain characteristics result in less sensitive CDR performance against input jitter and process, voltage, and temperature (PVT) variations. In addition, a built-in on-chip jitter monitor can be easily implemented using our ML-BBPD. A prototype 1.25-Gb/s CDR based on our ML-BBPD with a built-in jitter monitor is realized with 0.18- $\mu{\rm m}$ CMOS technology and its performance is successfully verified with measurement.

Reconfigurable Prototyping Microfluidic Platform for DEP Manipulation and Capacitive Sensing.

In this paper, we present a new rapid prototyping platform dedicated to dielectrophoretic microfluidic manipulation and capacitive cell sensing. The proposed platform offers a reconfigurable design including 4 independently programmable output channels to be distributed across 64 electrodes. Although its range of frequency covers up to 3.4 MHz, signal amplitude accuracy ( +/-10%) was demonstrated for frequencies up to 1 MHz and channel-to-channel phase shift setting was stable up to 1.5 MHz. A test of maximum resistive load showed a 10% attenuation of a 12 V peak-to-peak signal with a 22 Ω load. The platform has an advanced capacitive sensor to measure capacitance variation between in-channel electrodes with a sampling frequency up to 5 kH z. Experimental data of capacitive sensor showed a sensitivity of 100 fF. The sensor can be extended to 4 parallel measurements with lower frequency. We also present a new assembly technique for reusable microfluidic chip based on anisotropic adhesive conductive film, epoxy and PDMS. The proposed platform provides a wide range of control signals depending on the type of manipulation as sine, rectangular or square wave. The frequency range is extendible up to 3.4 MHz, in addition to a programmable phase shift circuit with a minimum phase step of 3.6(°) for each signal.

A 0.13 μm CMOS System-on-Chip for a 512 × 424 Time-of-Flight Image Sensor With Multi-Frequency Photo-Demodulation up to 130 MHz and 2 GS/s ADC

We introduce a 512 × 424 time-of-flight (TOF) depth image sensor designed in a TSMC 0.13 μm LP 1P5M CMOS process, suitable for use in Microsoft Kinect for XBOX ONE. The 10 μm × 10 μm pixel incorporates a TOF detector that operates using the quantum efficiency modulation (QEM) technique at high modulation frequencies of up to 130 MHz, achieves a modulation contrast of 67% at 50 MHz and a responsivity of 0.14 A/W at 860 nm. The TOF sensor includes a 2 GS/s 10 bit signal path, which is used for the high ADC bandwidth requirements of the system that requires many ADC conversions per frame. The chip also comprises a clock generation circuit featuring a programmable phase and frequency clock generator with 312.5-ps phase step resolution derived from a 1.6 GHz oscillator. An integrated shutter engine and a programmable digital micro-sequencer allows an extremely flexible multi-gain/multi-shutter and multi-frequency/multi-phase operation. All chip data is transferred using two 4-lane MIPI D-PHY interfaces with a total of 8 Gb/s input/output bandwidth. The reported experimental results demonstrate a wide depth range of operation (0.8–4.2 m), small accuracy error ( $ 1%), very low depth uncertainty ( $ 0.5% of actual distance), and very high dynamic range ( $>$ 64 dB).

Prospects for versatile phase manipulation in the TEM: Beyond aberration correction

In this paper we explore the desirability of a transmission electron microscope in which the phase of the electron wave can be freely controlled. We discuss different existing methods to manipulate the phase of the electron wave and their limitations. We show how with the help of current techniques the electron wave can already be crafted into specific classes of waves each having their own peculiar properties. Assuming a versatile phase modulation device is feasible, we explore possible benefits and methods that could come into existence borrowing from light optics where the so-called spatial light modulators provide programmable phase plates for quite some time now. We demonstrate that a fully controllable phase plate building on Harald Rose׳s legacy in aberration correction and electron optics in general would open an exciting field of research and applications.

Multilevel phase and amplitude modulation method for holographic memories with programmable phase modulator

The utilization of spatial quadrature amplitude modulation (SQAM) signals with amplitude and phase modulation is a simple method used to improve storage capacity in a holographic data storage system. We propose a multilevel phase and amplitude modulation method for holographic memories with a programmable phase modulator (PPM). In this method, holographic page data is recorded by a two-step exposure process for different phase-modulated data. There is no need to adjust the positions of spatial light modulators (SLM) with high accuracy because we use only one spatial modulator. We estimate the quality of 16 SQAM signals produced by our technique.

Erratum to: Phase correction using Programmable Phase Modulator (PPM) in optical coherence tomography

Erratum to: Phase correction using Programmable Phase Modulator (PPM) in optical coherence tomography

Wide-frequency range, dynamic matching network and power system for the "Shoelace" radio frequency antenna on the Alcator C-Mod tokamak.

A wide-frequency range (50-300 kHz) power system has been implemented for use with a new RF antenna - the "Shoelace" antenna - built to drive coherent plasma fluctuations in the edge of the Alcator C-Mod tokamak. A custom, dynamically tunable matching network allows two commercial 1 kW, 50-Ω RF amplifiers to drive the low-impedance, inductive load presented by the antenna. This is accomplished by a discretely variable L-match network, with 81 independently selected steps available for each of the series and parallel legs of the matching configuration. A compact programmable logic device provides a control system that measures the frequency with better than 1 kHz accuracy and transitions to the correct tuning state in less than 1 ms. At least 85% of source power is dissipated in the antenna across the operational frequency range, with a minimum frequency slew rate of 1 MHz/s; the best performance is achieved in the narrower band from 80 to 150 kHz which is of interest in typical experiments. The RF frequency can be run with open-loop control, following a pre-programmed analog waveform, or phase-locked to track a plasma fluctuation diagnostic signal in real time with programmable phase delay; the amplitude control is always open-loop. The control waveforms and phase delay are programmed remotely. These tools have enabled first-of-a-kind measurements of the tokamak edge plasma system response in the frequency range and at the wave number at which coherent fluctuations regulate heat and particle transport through the plasma boundary.

Compression of ultra-long microwave pulses using programmable microwave photonic phase filtering with > 100 complex-coefficient taps

Microwave photonic filters with arbitrary phase response can be achieved by merging high-repetition-rate electro-optic frequency comb technology with line-by-line pulse shaping. When arranged in an interferometric configuration, the filter features a number of programmable complex-coefficient taps equal to the number of available comb lines. In this work, we use an ultrabroadband comb generator resulting in a microwave photonic phase filter with >100 complex-coefficient taps. We demonstrate the potential of this filter by performing programmable chirp control of ultrawideband waveforms that extend over long (>10 ns) temporal apertures. This work opens new possibilities for compensating realistic linear distortion impairments on ultrabroadband wireless signals spanning over dozens of nanosecond temporal apertures.

Complex photonic lattices embedded with tailored intrinsic defects by a dynamically reconfigurable single step interferometric approach

We report sculptured diverse photonic lattices simultaneously embedded with intrinsic defects of tunable type, number, shape as well as position by a single-step dynamically reconfigurable fabrication approach based on a programmable phase spatial light modulator-assisted interference lithography. The presented results on controlled formation of intrinsic defects in periodic as well as transversely quasicrystallographic lattices, irrespective and independent of their designed lattice geometry, portray the flexibility and versatility of the approach. The defect-formation in photonic lattices is also experimentally analyzed. Further, we also demonstrate the feasibility of fabrication of such defects-embedded photonic lattices in a photoresist, aiming concrete integrated photonic applications.

The eCDR, a Radiation-Hard 40/80/160/320 Mbit/s CDR with internal VCO frequency calibration and 195 ps programmable phase resolution in 130 nm CMOS

A clock and data recovery IP, the eCDR, is presented which is intended to be implemented on the detector front-end ASICs that need to communicate with the GBTX by means of e-links. The programmable CDR accepts data at 40, 80, 160 or 320Mbit/s and generates retimed data as well as 40, 80, 160 and 320MHz clocks that are aligned to the retimed data. Moreover, all the outputs have a programmable phase with a resolution of 195ps. An internal calibration mechanism enables the eCDR to lock on incoming data even without the availability of any form of reference clock. The radiation-hard design, integrated in a 130nm CMOS technology, operates at a supply voltage between 1.2V and 1.5V. The power consumption is between 28.5mW and 34.5mW, depending on the settings. The eCDR can achieve a very low RMS jitter below 10ps.

Digitally tunable holographic lithography using a spatial light modulator as a programmable phase mask

In this paper, we study tunable holographic lithography using an electrically addressable spatial light modulator as a programmable phase mask. We control the phases of interfering beams diffracted from the phase pattern displayed in the spatial light modulator. We present a calculation method for the assignment of phases in the laser beams and validate the phases of the interfering beams in phase-sensitive, dual-lattice, and two-dimensional patterns formed by a rotationally non-symmetrical configuration. A good agreement has been observed between fabricated holographic structures and simulated interference patterns. The presented method can potentially help design a gradient phase mask for the fabrication of graded photonic crystals or metamaterials.

Microwave photonic signal processing

Photonic signal processing offers the advantages of large time-bandwidth capabilities to overcome inherent electronic limitations. In-fibre signal processors are inherently compatible with fibre optic microwave systems that can integrate with wireless antennas, and can provide connectivity with in-built signal conditioning and electromagnetic interference immunity. Recent methods in wideband and adaptive signal processing, which address the challenge of realising programmable microwave photonic phase shifters and true-time delay elements for phased array beamforming; ultra-wideband Hilbert transformers; single passband, widely tunable, and switchable microwave photonic filters; and ultra-wideband microwave photonic mixers, are described. In addition, a new microwave photonic mixer structure is presented, which is based on using the inherent frequency selectivity of the stimulated Brillouin scattering loss spectrum to suppress the carrier of a dual-phase modulated optical signal. Results for the new microwave photonic mixer demonstrate an extremely wide bandwidth operation of 0.2 to 20 GHz and a large conversion efficiency improvement compared to the conventional microwave photonic mixer.

A 10-Bit 2-GS/s DAC-DDFS-IQ-Controller Baseband Enabling a Self-Healing 60-GHz Radio-on-Chip

A 10-bit 2-GS/s mixed-signal baseband (BB) circuit, which enables a self-healing 60-GHz 4-Gb/s radio-on-chip implemented in a 65-nm complementary metal-oxide semiconductor, is described. The BB circuit autonomously senses and optimizes transmitter (TX) P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1dB</sub> , OIM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , and image suppression, reducing the yield loss because of process variations. On-chip test tones are generated using a 10-bit 2-GS/s current-steering digital-to-analog converter (DAC) and direct digital frequency synthesizer (DDFS). Using the generated test tones, the aforementioned impairments are measured by an envelope detector at the power amplifier output. Based on this information, the programmable digital IQ phase amplitude and offset controller (IQ_CTRL) in the BB circuit improves the TX image suppression from -32.4 to -42.6 dBc, and digital control signals generated by the on-chip self-healing controller heal the TX P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1dB</sub> and OIM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> from 9.5 to 13.2 dBm and from -32.5 to - 40 dBc, respectively. In terms of achieving the target specifications, namely, TX image suppression , , and , healing increases yield on ten dies from 0% to 100%. The BB circuit consumes only 49 mW, of which 37 mW comes from the DACs and 12 mW from the DDFS and the IQ_CTRL.

Variable shape or variable diameter flattop beam tailored by using an adaptive weight FFT-based iterative algorithm and a phase-only liquid crystal spatial light modulator

The variable shape or variable diameter flattop beam shaping technique by using an adaptive weight FFT-based iterative algorithm (AWFFT-IA) and a phase-only liquid crystal spatial light modulator (PO-LCSLM) is demonstrated. The algorithm is used to design the phase distribution for tailoring central symmetric laser beam into the desired shape or diameter flattop beam, the PO-LCSLM serves as dynamically programmable phase filters, which depend on the designed phase distributions, to retard the incident wavefront as we would expect. The experimental results show that the technique can realize variable shape or variable diameter flattop beam shaping.

An 8-Bit Digitally Controlled Programmable Phase Shifter Circuit for Sinusoidal Signals with 252∘ Phase Control Range

In this paper, the synthesis, design, and implementation of a programmable phase shifter circuit for sinusoidal signals is presented. The proposed circuit, built-up herein with operational amplifiers (OPAMPs), high precision resistors and low voltage switches, consists of a digitally controlled amplitude attenuator in combination with a single-tone orthogonalizer. Experimental results agree with theoretical background: the attained phase range was 252∘ in 256 steps with a median step of 0.9∘. The inaccuracy of the circuit was determined to be of 0.03 %. Contrary to other OPAMP approaches for sinusoidal signals reported in the literature and based on a first-order all-pass filter structure, the approximation suggested in this work is based on a different concept. The achieved results demonstrate the functionality of the system for the case of a sinusoidal signal with frequency of 1 kHz. Notwithstanding, the proposed architecture can be extended to operate at higher frequencies by using different building blocks with larger bandwidth. Furthermore, it can be extended as well to work out with other periodic input waveforms, like triangular shapes or square waves, with the use of an appropriate orthogonalizer.

Design and implementation of a low-cost multiple-range digital phase detector

This article describes the design, simulation, implementation and testing of a novel low-cost multiple-range programmable digital phase detector. The detector receives two periodic signals and calculates the ratio of the time difference to the time period to measure and display the phase difference. The resulting output values are in integer form ranging from −180° to 180°. Users can select the detector pre-set operation frequency ranges using a three-bit pre-scalar. This enables to use the detector for various applications. The proposed detector can be programmed over a frequency range of 10 Hz to 25 kHz by configuring its clock divider circuit. Detector simulations were conducted and verified using ModelSim and the design was implemented and tested using an Altera Cyclone II field-programmable gate array board. Both the simulation and actual circuit testing results showed that the phase detector has a magnitude of error of only 1°. The detector is ideal for applications such as power factor measurement and correction, self-tuning resonant circuits and in metal detection systems. Unlike other stand-alone phase detection systems, the reported system has the ability to be programmed to several frequency ranges, hence expanding its bandwidth.

Multitap microwave photonic filters with programmable phase response via optical frequency comb shaping

We present a programmable multitap microwave photonic filter with an arbitrary phase response operating over a broad bandwidth. Complex coefficient taps are achieved by optical line-by-line pulse shaping on a 10 GHz flat optical frequency comb using a novel interferometric scheme. Through high-speed real-time measurements, we demonstrate programmable chirp control of a waveform via phase filtering. This achievement enables us to compress broadband microwave signals to their corresponding bandwidth-limited pulse duration.

Programmable multiple true-time-delay elements based on a Fourier-domain optical processor

A new technique to realize an array of multiple true-time-delay elements, which can be independently and continuously tuned, is reported. It is based on a WDM parallel signal processing approach in conjunction with a diffraction-based Fourier-domain optical signal processor. Programmable linear optical phase transfer functions are realized to obtain different electrical true-time delays. The technique can scale to a large number of wideband true-time-delay lines, with continuously tunable programmable delay. Results demonstrate multiple true-time-delay elements with independent tuning control and verify the concept by tuning the free spectral range of a microwave photonic notch filter. To our best knowledge, this is the first demonstration of multiple independently controllable true-time-delay lines for microwave photonic systems.

Optical Control of Plasmonic Bloch Modes on Periodic Nanostructures

We study and actively control the coherent properties of surface plasmon polaritons (SPPs) optically excited on a nanohole array. Amplitude and phase of the optical excitation are externally controlled via a digital spatial light modulator (SLM) and SPP interference fringe patterns are designed and observed with high contrast. Our interferometric observations reveal SPPs dressed with the Bloch modes of the periodic nanostructure. The momentum associated with these dressed plasmons (DP) is highly dependent on the grating period and fully matches our theoretical predictions. We show that the momentum of DP waves can, in principle, exceed the SPP momentum. Actively controlling DP waves via programmable phase patterns offers the potential for high field confinement applicable in lithography, surface enhanced Raman scattering, and plasmonic structured illumination microscopy.

Increasing efficiency of a linear-optical quantum gate using electronic feed-forward

We have successfully used a fast electronic feed forward to increase the success probability of a linear optical implementation of a programmable phase gate from 25% to its theoretical limit of 50%. The feed forward applies a conditional unitary operation which changes the incorrect output states of the data qubit to the correct ones. The gate itself rotates an arbitrary quantum state of the data qubit around the z-axis of the Bloch sphere with the angle of rotation being fully determined by the state of the program qubit. The gate implementation is based on fiber optics components. Qubits are encoded into spatial modes of single photons. The signal from the feed-forward detector is led directly to a phase modulator using only a passive voltage divider. We have verified the increase of the success probability and characterized the gate operation by means of quantum process tomography. We have demonstrated that the use of the feed forward does not affect either the process fidelity or the output-state fidelities.