Nonlinear Frequency-Modulation Distortion Analysis for VCO Based on Harmonic Balance Method

The analysis methods for the steady-state responses of the voltage tuning negative resistance oscillator (voltage-controlling oscillator, VCO) by the microwave nonlinear autonomous circuit harmonic balance method in millimeter-wave bands are studied in the paper. Firstly, the quasi-periodic characteristic of the steady-state response of the VCO modulated by a periodic signal is proved. Then, on the bases of the harmonic balance analysis and the inter-modulation balance analysis, a novel method for obtaining the steady-state tuning performance and the nonlinear frequency-modulation distortion characteristic of the VCO is presented. The total analysis process is aimed to a kind of NRD-guide Gunn diode VCO. The large-signal lumped equivalent circuit model of the millimeter-wave P⁺N-junction varactor is also given for explaining the algorithm and the principle of the NRD-guide VCO.     

Discontinuity of NRD-Guide and Its Application in Millimeter Wave Circuits

In this paper, the performances of two typical discontinuous structures of the NRD-guide, the traverse metallic rod to disturb an incident wave and the traverse probe to excite required modes, are analyzed and computed by utilizing the theory of modes orthogonality of the NRD-guide. The moment method is used to evaluate the current distribution on the rod and probe and the affection of some higher-order modes is taken into account simultaneously. On these bases, the multitone exciting steady states of two kinds of important circuits that employ the above discontinuous structures, the NRD-guide crossbar balanced mixer and the LSM ₁₁ ⁰ -mode oscillator, are simulated by the harmonic balance technique based on the multi-dimensional discrete Fourier transformation (MDFT-HB method).     

Analysis and application of NRD-guide excitors

In this paper, the NRD-guide excitors using a length of coaxial line which consists of a rectangle external conductor and a thin round inner conductor are presented, and the characteristics of the input impedances of LSE ₁₁ ^o mode and LSM ₁₁ ^o mode at the insertion points are analysed and calculated by using the method of the rector Green's function respectively. The computation results show that the mode excitors are able to improve the operating modes matching between NRD-guide and the quasi-TEM transmission line. The structures are suitable for fabrication LSE ₁₁ ^o mode oscillator and LSM ₁₁ ^o mode oscillator to compose millimeter wave NRD-guide integrated front ends. An example of an LSE ₁₁ ^o mode oscillator in Ka-band is given. Its oscillation frequency and output power could be easily adjusted by changing the parameters of the excitor.     

Steady State Responses of NRD-Guide Crossbar Balanced Mixer in MM-Wave Band

The periodic and quasi-periodic steady states of the nonradiative dielectric waveguide (NRD-guide) crossbar single-balanced mixer excited by single tone or dual tones in mm-wave band are deeply researched in the paper. Based on the wideband dispersion characteristics, the mode self-contained property and the modes orthogonality and a series of modes excitation criterions of the NRD-guide, a novel mixer is designed and analyzed. Two important parameters, the local oscillator and incident wave inductive electromotive forces corresponding to the LSE/LSM mode-converter and LSM-mode probe respectively, are calculated firstly by using the wire-antenna theory and the moment method. According to the theorem of band-pass signal sampling, a kind of integrated and general quasi-periodical steady-state responses algorithm for the nonlinear microwave/mm-wave circuits excited by multiple tones, the inter-modulation balance method based on the multi-dimension discrete Fourier transformation (MDFT-IMB), is designed and then successfully applied to calculate the performances of the above NRD-guide mixer.     

The development of nonradiative dielectric waveguide transmitting front-end in Ka-band

The operating theory,design method and experimental results of the nonradiative dielectric waveguide (NRD-guide) transmitting front-end in millimeter wave band are related in details in this paper. As a kind of dielectric waveguide,the NRD-guide possesses fine transmission performances, and it can be used to fabricate the millimeter wave hyterodyne integrated circuits. The two kinds NRD-guide transmitting front-ends substantiated in the paper, the voltage controlling oscillator(VCO) and twin-Gunn-diode power-combiner,have very similar structures to each other and possess compact sizes, fine machinery and electric performances.For the VCO front-end in Ka-band, the frequency modulation band is greater than 150MHz, the output power is larger than 20mW.For the power-combiner, the output power is larger than 40mW,the combination efficiency is better than 90%,the frequency stabilization reaches 1.68×10^–5. Combined with the receiving front-end reported before,the transmitter and receiver can be composed to a dielectric waveguide R/T module to be applied in some millimeter wave sub-systems.     

Simple frequency measurement chain to 30 THz

We report harmonic mixing experiments between a 72 GHz mm-wave and 3.7 THz NH₃-laser radiation, as well as between 3.7 THz and the 10 m R(30) CO₂-laser line. For the former mixing a semiconductor diode is used, while for the higher frequencies an MIM tunnel diode served as the nonlinear element. Beat signals are of sufficient signal to noise ratio for precise optical frequency measurement.Visiting from National Institute of Metrology, Beijing, P. R. China     

Frequency Sources in W-band Radar Front-end with Low Phase Noise

A W-band coherent stepped-frequency pulsed radar front-end is developed. It consists of a millimetre wave transmitting source, a mm-wave local source, a DDS with multi frequency points output and two microwave sources serving as local oscillators. All the sources are coherent with the 120 MHz referenced crystal oscillator. The mm-wave sources are realized by frequency multiplier chain, up-conversion and injection locking. The phase noise of fundamental-wave injection-locked W-band harmonic Gunn oscillator output signal achieves −98 dBc/Hz at 10 kHz offset and the spurious output is less than −50 dBc. The received intermediate frequency signal is also presented.     

A Very Low-Noise Integrated 3MM-Wave Schottky Diode Mixer and PHEMT IF Amplifier

An integrated 3mm-wave Schottky diode mixer and pseudomorphic high-electron-mobility transistor (PHEMT) IF amplifier with record noise performance at room temperature is described. The design has shown the room-temperature double-sideband (DSB) receiver noise temperature T_R^DSB of 190 K at 100 GHz due to a very low conversion loss in the full-height waveguide mixer and an ultra-low noise of the PHEMT IF amplifier. The receiver noise temperature has been reduced by a factor of 1.5 in comparison with the best previously reported 3mm-wave Schottky diode mixer receiver.     

Analysis of autodyne effect of an rf oscillator

Theoretical and experimental results of investigations on a pulse-modulated autodyne oscillator affected by its own reflected radiation are presented. The main relations for the analysis of autodyne response as a function of reflected radiation delay time are obtained. Characteristics of autodyne self-oscillations, which allow improving their performance and extend functional capabilities of autodyne systems for short-range radar applications, are discussed. Experimental results are obtained for a TIGEL-08 oscillator module manufactured on the basis of a mm-wave Gunn diode using a hybrid-integral technology. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 64–70, March, 2008.     

Field-domain dynamics in negative-effective-mass terahertz oscillators

We have theoretically studied electric-field-domain dynamics and current self-oscillations in dc-biased negative-effective-mass (NEM) p ⁺ pp ⁺ diodes. The formation and traveling of electric-field domains in the diodes are investigated in detail with a realistic treatment of the scatterings contributions from carrier-impurity, carrier-acoustic phonon, and carrier-optic phonon within the balance-equation theory. The interesting patterns of the spatiotemporal electric-field domains are shown as a gray density plot with the applied bias as a controlling parameter. It is found that, the applied bias could largely influence the current patterns and self-oscillating frequencies, which lie in the THz range for the NEM p ⁺ pp ⁺ diode with a submicrometer p-base. The NEM p ⁺ pp ⁺ diode may therefore be developed as an electrically tunable THz-frequency oscillator.Received: 18 July 2003, Published online: 23 December 2003PACS: 73.61.Ey III-V semiconductors - 73.50.Fq High-field and nonlinear effects - 85.30.Fg Bulk semiconductor and conductivity oscillation devices (including Hall effect devices, space-charge-limited devices, and Gunn effect devices) - 85.30.De Semiconductor-device characterization, design, and modeling     

Oscillator strength measurements of the 4s5s 3S1 → 4snp 3Po2 Rydberg transitions of zinc

In the present experimental work, oscillator strengths of the 4s5s ³S₁ → 4snp ³P^o₂ (18?≤?n?≤?53) Rydberg transitions of zinc are reported. The stepwise laser excitation from the ground state 4s^{2 1}S₀ was achieved using three dye laser beams simultaneously pumped by the second (532?nm) and third (355?nm) harmonics of a Q-switched Nd: YAG (Neodymium-doped yttrium aluminum garnet) laser. The vapor containment and detection system was a single wire thermionic diode ion detector operating in space charge limited mode. A trend of the above-mentioned f-values from n?=?18 to 53 versus the principle quantum number n has been presented. Furthermore, continuity has been verified between the discrete f-values and the oscillator strength density at the threshold.     

A new type NRD-guide receiving front-end in Ka-band

A new type millimeter-wave receiving frond-end using NRD-guide as internal transmission line is presented in this paper. The receiving frond-end consists of a NRD-guide crossbar balanced mixer, a NRD-guide LSE mode local oscillator and two impedance-converters at two input ports of the mixer circuit. Firstly, the propagation characteristics of some transmission modes often used in NRD-guide are given, and the conditions which these modes are applied as the operating modes are discussed. Secondly, the principle of the balanced mixed which is regarded as the key circuit unit in the receiving frond-end is analysed by using vector Green's function, and the conversion loss of the mixer is computed with an equivalent circuit in Ka-band. And then, from the view of obtaining the optimum performances of the whole receiving frond-end, some methods of designing local oscillator are expound. Some experimental results of the receiving frond-end at Kaband are given in the paper lastly. Because the frond-end have the impedance matching and converting circuits, it possesses better electrical performance. The integrated frond-end which have compact size and excellent shock strength is suitable for varied millimeter-wave system.     

Design and manufacture of planar GaAs Gunn diode for millimeter wave application

GaAs-based planar Gunn diodes with AlGaAs hot electron injector have been successfully developed to be used as a local oscillator of 76 GHz in monolithic millimeter-wave integrated circuits.We designed two kinds of structure diode,one has a fixed distance between the anode and cathode,but has variational cathode area,the other has a fixed cathode area,but has different distances between two electrodes.The fabrication of Gunn diode is performed in accordance with the order of operations:cathode defining,mesa etching,anode defining,isolation,passivation,via hole and electroplating.A peak current density of 29.5 kA/cm 2 is obtained.And the characteristics of negative differential resistance and the asymmetry of the current-voltage curve due to the AlGaAs hot electron injector are discussed in detail.It is demonstrated that the smaller size of active area corresponds to the smaller current,and the shorter distance between anode and cathode also corresponds to the lower threshold voltage and higher peak current,and hot electron injector can effectively enhance the radio frequency conversion efficiency and output power.     

W-band gunn second subharmonically locked oscillator

In this paper, the averaging method is used to analyse the performance of second subharmonically injection locked Gunn oscillator. Some useful expressions such as the locking range, output response, output impedance of nonlinear device in fundamental and subharmonic frequency are obtained. a W — band subharmonically locked Gunn oscillator is developed and experimental result demonstrates the validity of this analysis.     

Hot electron injector Gunn diode for advanced driver assistance systems

This paper reviews the main aspects of the design, fabrication and characterization of GaAs Gunn diodes intended to be used in advanced driver assistance systems. The corresponding Gunn diode based oscillators operate at the microwave frequency of 77 GHz and deliver an output power up to 19.2 dBm (83.2 mW). To fulfill the high demands of the automotive industry, temperature stability and a high grade of frequency purity, the Gunn diode structure includes a hot electron injector. This is based on the heteroepitaxy of a graded gap Al_xGa_1-xAs layer and an adjacent thin highly doped GaAs layer. The hot electron injector properties are investigated using dc and rf electrical measurements, including the temperature influence as well. Specific production related data of the cavity oscillators using our Gunn diodes are presented. New alternatives, such as the resonant tunneling emitter as a hot electron injector and the Gunn diode based MMIC as oscillator, are introduced. PACS 85.30.-z; 73.40.-c; 07.57.Hm; 84.30.Ng; 85.30.Fg     

Millimeter Wave Gunn Diode Oscillator Design Based on FDTD Method*

In this paper, a millimeter wave Gunn diode oscillator is analyzed and designed by the finite-difference time-domain (FDTD) method. The design results indicate that the oscillator has an oscillation frequency of 45.0GHz and a higher oscillation voltage. Based on the circuit equations and an integral transform, an improved matrix method is utilized for the oscillator design. This method is also extended to model the hybrid network which is constructed by the high order linear elements and the nonlinear elements with arbitrary connections. The experience shows that the improved FDTD method is stable with the time step length Δt based on the Courant condition. *This work was supported by the National Natural Science Foundation of China.     

The digital predistortion of non-linear frequency modulation of voltage-controlling-oscillator in MM-band

The reason and rectification method of the non-linear frequency modulation of voltage-controlling-oscillator in millimeter-wave band have been presented in this paper. The digital predistortion for the controlling signal of the varactor in VCO possesses high rectification sensitivity, simple circuit and convenient adjustment. The method can be used in mm-wave and microwave VCOs that are fabricated by all kinds' transmission lines, and can eliminate the dispersion of FM characteristic in VCOs that are usually caused by the machining deviation and the inconsistent parameters of semiconductors. The digital predistortion technique has been applied in NRD-guide VCO in Ka-band, which main performances are: f0 = 36.30648GHz, the frequency-stability reaches 2.26×10^–5, the maximum frequency-deviation is 150MHz, the linear-FM error is less than 5%.     

Diode-pumped CW Nd:YAG laser at 1116 nm based on the <Superscript>4</Superscript><Emphasis Type="Italic">F</Emphasis><Subscript>3/2</Subscript>-<Superscript>4</Superscript><Emphasis Type="Italic">I</Emphasis><Subscript>11/2</Subscript> transition

We describe the output performances of the 1116 nm ⁴ F _3/2-⁴ I _11/2 transition (generally used for a 1064 nm transition) in Nd:YAG under in-band pumping with diode laser at the 809 nm wavelength. An end-pumped Nd:YAG crystal yielded 680 mW of continuous-wave (CW) output power for 18.2 W of incident pump power. Moreover, intracavity second-harmonic generation (SHG) has also been achieved with a power of 97 mW at 558 nm by using a LiB₃O₅ (LBO) nonlinear crystal. The yellow-green beam quality factor M ² was less than 1.21. The yellow-green power stability was less 2.5% in 4 h.     

Thickness dependent optical dispersion parameters and nonlinear optical properties of nanostructured Cr doped CdO thin films

Cr doped CdO thin films were deposited on glass substrates by reactive DC magnetron sputtering with varying film thickness from 250 to 400 nm. XRD studies reveal that the films exhibit cubic structure with preferred orientation along the (2 0 0) plane. The optical transmittance of the films decreases from 92 to 72%, whereas the optical energy band gap of the films decreased from 2.88 to 2.78 eV with increasing film thickness. The Wemple–DiDomenico single oscillator model has been used to evaluate the optical dispersion parameters such as dispersion energy (E_d), oscillator energy (E_o), static refractive index (n_o) and high frequency dielectric constant (ε_∞). The nonlinear optical parameters such as optical susceptibility (χ⁽¹⁾), third order nonlinear optical susceptibility (χ⁽³⁾) and nonlinear refractive index (n₂) of the films were also determined.     

Diode-pumped continuous-wave Nd:YAP laser emitting at 1073 nm based on the 4F3/2-4I11/2 transition

We describe the output performances of the 1073 nm ⁴ F _3/2 → ⁴ I _11/2 transition (generally used for a 1064 nm transition) in Nd³⁺:YAlO₃ (Nd:YAP) under in-band pumping with diode laser at the 803 nm wavelength. An end-pumped Nd:YAP crystal yielded 390 mW of continuous-wave (CW) output power for 17.8 W of incident pump power. Moreover, intracavity second-harmonic generation has also been achieved with a power of 38 mW at 536 nm by using a LiB₃O₅ (LBO) nonlinear crystal. The green beam quality factor M ² was less than 1.33. The blue power stability was less 3.5% in 4 h.