Flicker noise conversion in CMOS LC oscillators: capacitance modulation dominance and core device sizing

This paper reports a low-voltage low-power injection-locked oscillator suitable for short range wireless transmitter applications in a wireless body area network (WBAN). Low-power transmitter with high efficiency is a major design challenge for short range wireless communication. Unlike conventional transmitters used for cellular communication, injection-locked transmitter shows reduced power consumption and high transmitter efficiency. The core block of an injection-locked transmitter is an injection-locked oscillator. In this work a low-voltage low-power injection-locked LC oscillator has been designed and fabricated employing self-cascode structure and body-terminal coupling. The proposed oscillator has been realized using 0.18-μm RF CMOS process. Experimental results indicate that the prototype oscillator can operate with a supply voltage as low as 0.9 V and consumes only 1.4 mW of power. The relatively low-voltage and low-power operation of the design makes it highly suitable for low-power transmitter applications.     

一种毫米波宽锁定范围的注入锁定倍频器设计

为提高毫米波段倍频器在低功耗下的工作带宽,采用IHP130 nm SiGe BiCMOS 工艺,设计了一种采用双端注入技术的毫米波宽锁定范围注入(DEI)锁定倍频器。该注入锁定倍频器主要由谐波发生器和带有尾电流源的振荡器构成,由巴伦产生差分信号双端注入振荡器的形式提高三次谐波注入强度,使其在E、W 等波段输出宽锁定范围和良好相位噪声性能的三倍频信号。仿真结果表明,注入锁定倍频器在工作电压为1.2 V,输入信号功率为0 dBm时,其锁定范围在57~105 GHz 内。在相同工作电压和输入信号功率下,输入频率为32 GHz 时,一次、二次和四次谐波抑制大于20 dBc,功耗为9.1 mW。     

Analysis of a homodyne receiver using an injection-lockedsemiconductor laser

The authors study an optical homodyne receiver using an injection-locked semiconductor laser as a local oscillator. The carrier recovery process introduces a phase error, and the calculation of its statistical properties leads to the evaluation of the receiver performance. The analysis shows the dependence of the receiver performance on the injected power and the phase detuning, between the transmitter, and local oscillator electric fields. The receiver performance is affected by the phase noises of the transmitter and local oscillators, by the shot noise of the detectors in the receiver, and by the modulation noise resulting from the injection locking of the local oscillator by a modulated signal     

High Average-Efficiency Multimode RF Transmitter Using a Hybrid Quadrature Polar Modulator

This paper presents a hybrid quadrature polar modulator (HQPM) to drive the power amplifier (PA) highly efficiently in a wireless RF transmitter required for multimode operation. For enhancing the transmit efficiency, a switching-mode PA realized as Class-E design is used in the transmitter. The HQPM consists of a quadrature modulator for processing the RF modulated carrier and a Class-S modulator for processing the supply-voltage signal. The quadrature modulator and the Class-S modulator deliver the output signals with proportional envelope variation before being inserted into the RF-input terminal and the supply-voltage terminal of a Class-E PA, respectively, causing the double envelope modulation to distort the modulated RF signal at the PA output. Therefore, a digital predistorter is embedded in the HQPM for compensation. The proposed HQPM-based transmitter can help reducing the average dc and input RF powers and the output feedthrough levels so as to enhance power added efficiency and adjacent channel power rejection remarkably.     

Transmission-Type Injection Locking of GaAs Schottky-Barrier FET Oscillators

Transmission-type injection-locked oscillators equipped with both signal-input and power-output ports are studied. A comparison with traditional reflection-type injection-locked oscillators, in which a signal is injected into the output port of the oscillator, is presented theoretically. It is shown that the Iocking range of transmission types always differs from the reflection type by a factor of G/sub s// G/sub p/ where G/sub s/ represents the maximum stable gain of the two-port oscillator and G/sub p/ represents the square root of the output power ratio of the two ports. Experiments on common-source injection-locked oscillators using GaAs FET chips are described and show that, with transmission types, a 1.8 times wider Iocking range can be obtained than with reflection types. Furthermore, investigation of FM noise for both types of injection revealed lower off-carrier FM noise for transmission types than reflection types, even though the Iocking gain of the transmission types was kept the same as that of reflection types. Thus overall features of transmission-type injection locking were found to be advantageous for FM signal amplification even though there is a minimal power loss at the signal input port.     

Understanding linearity in wireless communication amplifiers

This paper investigates the linearity of active devices and amplifiers that have modulated input signals. We describe an implementation of a mathematical technique for calculating spectral regrowth due to the nonlinear amplification of modulated signals typically used in wireless communication systems. This technique only requires knowledge of the single-tone gain and phase data as a function of input power and can be applied to any modulated signal given (a) the device or amplifier characteristics do not change significantly over the bandwidth of the input signal and (b) the modulation frequencies are much less than the carrier frequency. Verification of the mathematical technique is presented using examples of measured and calculated spectra for π/4-differential quadrature phase shift keying (DQPSK) personal handy phone system (PHS) and code division multiple access (CDMA) Offset-QPSK personal communication system (PCS) modulation schemes. This calculation technique is essential in determining fundamental tradeoffs between device performance (linearity, output power, gain, and power-added efficiency) and device bias conditions and load impedance     

防破音D类音频功放的设计与应用

随着多媒体便携设备的普及,音频功放已经成为音频部分的标准配置,D类功放以其高品质高效的特点得到了越来越广泛的应用。在便携产品中,音频功放由于输入音乐信号过大或者电源电压过低,会产生削顶失真。采用防破音技术,可以通过自动增益调节技术来提供一个完美的解决方案。文章介绍了常见的防破音技术,提出了一种改进的AGC(自动增益控制)技术在D类功放中的设计与应用。改进的AGC技术通过对PWM输出的采样来判断失真程度,依据失真程度用防破音电路产生的PWM波形来自动调节运放增益,实现最大功率的无失真输出。     

Bandpass delta-sigma class-S amplifier

A class-S amplifier with a bandpass delta-sigma modulated input is demonstrated using CMOS devices at 10 MHz. With a two-tone modulated input, third-order intermodulation products below -40 dBc were measured, with an output power of 26 dBm and a drain efficiency of 33%. This new amplifier topology demonstrates promising performance for simultaneously achieving high linearity and efficiency     

High-Efficiency Envelope-Tracking W-CDMA Base-Station Amplifier Using GaN HFETs

A high-efficiency wideband code-division multiple-access (W-CDMA) base-station amplifier is presented using high-performance GaN heterostructure field-effect transistors to achieve high gain and efficiency with good linearity. For high efficiency, class J/E operation was employed, which can attain up to 80% efficiency over a wide range of input powers and power supply voltages. For nonconstant envelope input, the average efficiency is further increased by employing the envelope-tracking architecture using a wide-bandwidth high-efficiency envelope amplifier. The linearity of overall system is enhanced by digital pre-distortion. The measured average power-added efficiency of the amplifier is as high as 50.7% for a W-CDMA modulated signal with peak-to-average power ratio of 7.67 dB at an average output power of 37.2 W and gain of 10.0 dB. We believe that this corresponds to the best efficiency performance among reported base-station power amplifiers for W-CDMA. The measured error vector magnitude is as low as 1.74% with adjacent channel leakage ratio of -51.0 dBc at an offset frequency of 5 MHz     

SIW-Based W-Band Low Phase-Noise Injection-Locked Harmonic Oscillator

A W-band planar injection-locked harmonic oscillator (ILHO) based on substrate integrated waveguide (SIW) is implemented. This ILHO has a free-running output frequency around 94.6?GHz while the technique of harmonic extraction from diodes is used as a frequency multiplier. It has an output locking bandwidth of 300?MHz (from 94.45 to 94.75?GHz) as injecting a signal around 47.3?GHz with the fundamental injection-locked behavior, and the output power is more than 5.8 dBm. The combination of simple synchronization with a low-frequency reference signal allows the generation of stable and low phase-noise W-band signals with a fully integrated planar source.     

A 200-MHz IF BiCMOS signal component separator for linear LINCtransmitters

The linear amplification with nonlinear components (LINC) transmitter is an architecture that provides linear amplification using nonlinear but power efficient amplifiers. The signal component separator (SCS) is a crucial signal processing function of LINC. It forms two constant-amplitude phase-modulated signal components from the input signal. Due to the nonlinear signal processing involved, digital signal processing (DSP) implementation of the SCS at baseband has so far been assumed to be the best choice although it suffers from matching, bandwidth and power consumption problems. In this paper a new SCS architecture based on analog integrated circuit techniques is presented to avoid the disadvantages in a DSP based realization. A 200-MHz IF SCS chip using the proposed architecture was designed and fabricated in a 0.8 μm BiCMOS process. An experimental LINC transmitter was built with the SCS chip, nonlinear amplifiers and a power combiner. Test results showed that spurious levels around -50 dBc could be obtained with a π/4-shifted DQPSK modulated North American Digital Cellular (NADC) signal. This implies a high degree of linearity in the implemented LINC transmitter     

A Polar Modulator Using Self-Oscillating Amplifiers and an Injection-Locked Upconversion Mixer

A polar modulator for use with non-constant envelope signals is presented. Techniques for efficient behavior of both the amplitude (AM) and phase (PM) path are introduced. The amplitude modulation technique is based on asynchronous pulse-width modulation of a phase-modulated RF signal. The digital signal generated in this way is suited for amplification using a nonlinear, efficient type of PA, while preserving the AM modulation, since this information is present in the signal. The efficiency of the switching amplifier is less dependent of the output power, compared to class B operation. Using a self-oscillating, asynchronous type of pulse-width modulator, the spurs are concentrated in narrow bands well separated from the signal band. These switching spurs are filtered out by the filters already present in the transmitter. The feasibility of this RF-pulse-width-modulation is proven by measurements with amplitude modulated signals on a prototype in 0.18 mum CMOS. Unmodulated, the circuit is able to deliver a peak output power of 8.26 dBm with a drain efficiency of 35%. In the phase-modulation path of the polar modulator, injection locking of an oscillator is used as a single-stage high-gain amplifier. Avoiding multiple stages and related power loss improves the overall power efficiency.     

Mixer for low voltage operation

A very high conversion gain mixer of frequency 350 MHz is designed using the injection-locked technique. The mixer is based on a common-base Clapp oscillator which is free-running at a frequency of 350 MHz. Using the injection-locked technique, the nonlinear resistance of the oscillator is modulated by the injection source which provides negative resistance amplification to the RF signal. It gives conversion gain as high as 30 dB with good noise performance     

All-optical NOR gate based on injection-locking effect in a semiconductor laser

A scheme for all-optical NOR logic gate is proposed based on injection-locking effect in a semiconductor laser. In this scheme, signal light injection into the laser will cause frequency shift of laser modes, as a result, the probe light into the laser can be switched between injection-locked and unlocked status, and its output power will be modulated. Theoretical analysis for this scheme is carded out by using a model to describe the dynamics of the injection-locked laser. By numerical simulation, the influence of laser bias current, laser length, injected signal power and signal frequency on the output performance of NOR logic gate is quantitatively analyzed.     

Direct optical injection locking of 20 GHz superlattice oscillators

For the first time, a direct optically injection-locked oscillator based on the Esaki-Tsu effect in superlattices is reported. The microwave output power is -7 dBm at 20 GHz with an optical input power of -10 dBm at a wavelength of 1.3 μm     

Quasi-optical 150-GHz power combining oscillator

A quasi-optical power combiner for a five-element in-line oscillator array is experimentally investigated at 150 GHz. The combiner consists of a periodic dielectric phase grating (hologram) which transforms the near-field of a rectangular horn antenna array into a pseudo-plane wave. The horn array is excited by IMPATT oscillators operating uniformly in both amplitude and phase. A dual offset reflector set-up transforms the pseudo-plane wave to a Gaussian beam which matches the field pattern of a dual mode receiving antenna. Even though an inter-element spacing of 9.5 /spl lambda/ has been chosen, the passive structure gives a power combining efficiency of 74.1%. The power combining oscillator has been operated in both free-running and injection-locked mode. A CW output power of 78.0 mW and 83.5 mW was measured for the free-running and injection-locked oscillator, respectively, which is corresponding to a power combining efficiency of 66.5% and 71.2%, respectively.     

Analysis of oscillators with external feedback loop for improvedlocking range and noise reduction

A simple scheme for enhancing the locking/capture range and phase-noise performance of FET-based voltage-controlled oscillators (VCO's) is presented using a low-pass feedback loop from the oscillator output to the varactor tuning port. The nonlinearity of the FET provides for mixer or phase detector behavior (a self-oscillating mixer). The resulting feedback oscillator advantageously combines the principles of a conventional injection-locked oscillator (ILO) and phase-locked loop (PLL), which we refer to as an injection-locked phase-locked loop (ILPLL). The analysis suggests that the ILPLL can be designed for superior near-carrier phase-noise performance compared with conventional ILO or PLL circuits. A 10-GHz prototype was fabricated, which demonstrated a locking range more than double that of the isolated VCO injection-locking range over the same range of injected signal power     

A 63-W W-Band Injection-Locked Pulsed Solid-State Transmitter

A high-power three-stage W-band injection-locked pulsed solid-state transmitter using four hybrid-coupled two-diode IMPATT power combiners as the final stage has been developed. Coherent peak output power of 63 W and 92.6 GHz was achieved. The transmitter was operated at 100-ns pulsewidth and 0.5-percent duty cycle. This transmitter development was directed at achieving a high-power output that would be useful for future miltimeter-wave system applications.     

An Ultra-Low-Power Injection Locked Transmitter for Wireless Sensor Networks

This paper presents the principles for designing low-power transmitters for wireless sensor networks. Based on these principles, an injection-locked transmitter is implemented in a standard 0.13-$muhbox m$CMOS process and packaged using chip-on-board assembly. The transmitter utilizes a film bulk acoustic resonator (FBAR) to obtain a stable carrier at 1.9 GHz. At 0 dBm output power, the transmitter achieves an efficiency of 32% at 50 kb/s and 28% at 156 kb/s. With 50% on-off keying, the transmitter consumes 1.6 and 1.8 mW, respectively.     

A Discrete‐Amplitude Pulse Width Modulation for a High‐Efficiency Linear Power Amplifier

A new discrete‐amplitude pulse width modulation (DAPWM) scheme for a high‐efficiency linear power amplifier is proposed. A radio frequency (RF) input signal is divided into an envelope and a phase modulated carrier. The low‐frequency envelope is modulated so that it can be represented by a pulse whose area is proportional to its amplitude. The modulated pulse has at least two different pulse amplitude levels in order that the duty ratios of the pulse are kept large for small input. Then, an RF pulse train is generated by mixing the modulated envelope with the phase modulated carrier. The RF pulse train is amplified by a switching‐mode power amplifier, and the original RF input signal is restored by a band pass filter. Because duty ratios of the RF pulse train are kept large in spite of a small input envelope, the DAPWM technique can reduce loss from harmonic components. Furthermore, it reduces filtering efforts required to suppress harmonic components. Simulations show that the overall efficiency of the pulsed power amplifier with DAPWM is about 60.3% for a mobile WiMax signal. This is approximately a 73% increase compared to a pulsed power amplifier with PWM.