Wideband Frequency Synthesizer at X/Ku Band by Mixing and Phase Locking of Half Frequency Output of VCO

A wideband low phase noise frequency synthesizer at X/Ku band has been developed by using phase locking and mixing technique at half frequency of voltage controlled oscillator (VCO). The half frequency output signal of the VCO is down converted by a balanced mixer at C band to obtain an intermediate frequency (IF) signal used for phase locking of the VCO. An ultra low phase noise local signal source at 6 GHz is developed with a frequency multiplying chain driven by a 100 MHz oven controlled crystal oscillator (OCXO). Coupling circuit outside the VCO chip to the mixer does not need to be specially designed, which is beneficial to simplify the circuit scheme and improve the phase noise performance. Measurement results show that the phase noise of the output signal at 10.6 GHz to 11.8 GHz and 12.3 GHz to 13.0 GHz is better than −102 dBc/Hz at 10 kHz away form the carrier center. This frequency synthesizer can be used as local signal source or driving source for the development of wideband millimeter-wave frequency synthesizer systems.     

AN UNCOOLED VERY LOW NOISE SCHOTTKY DIODE RECEIVER FRONT-END FOR MIDDLE ATMOSPHERIC OZONE AND CARBON MONOXIDE MEASUREMENTS

The paper describes an uncooled front-end of the Schottky diode receiver system, which may be applied for observations of middle atmospheric ozone and carbon monoxide thermal emission lines at frequencies 110.8 GHz and 115.3 GHz, respectively. The mixer of the front-end has utilized high-quality Schottky diodes that allowed us to reduce the mixer conversion loss. The combination of the mixer and an ultra-low-noise IF amplifier in the one integrated unit has resulted in double-sideband (DSB) receiver noise temperature of 260 K at a local oscillator (LO) frequency of 113.05 GHz in the instantaneous IF band from 1.7 to 2.7 GHz. This is the lowest noise temperature ever reported for an uncooled ozone receiver system with Schottky diode mixers.     

An I/Q mixer with an integrated differential quadrature all-pass filter for on-chip quadrature LO signal generation

A down-conversion in-phase/quadrature (I/Q) mixer employing a folded-type topology, integrated with a passive differential quadrature all-pass filter (D-QAF), in order to realize the final down-conversion stage of a 60 GHz receiver architecture is presented in this work. Instead of employing conventional quadrature generation techniques such as a polyphase filter or a frequency divider for the local oscillator (LO) of the mixer, a passive D-QAF structure is employed. Fabricated in a 65 nm CMOS process, the mixer exhibits a voltage gain of 7-8 dB in an intermediate frequency (IF) band ranging from 10 MHz-1.75 GHz. A fixed LO frequency of 12 GHz is used to down-convert a radio frequency (RF) band of 10.25-13.75 GHz. The mixer displays a third order input referred intercept point (IIP₃) ranging from -8.75 to -7.37 dBm for a fixed IF frequency of 10 MHz and a minimum single-sideband noise figure (SSB-NF) of 11.3 dB. The mixer draws a current of 6 mA from a 1.2 V supply voltage dissipating a power of 7.2 mW.     

A Broad-Band Second-Harmonic Mixer Covering 76-106 GHz

A broad-band second-harmonic millimeter-wave mixer has been constructed. The circuit consists of a single unencapsulated Schottky-barrier diode and embedding network which includes a wave absorber in the IF output terminal. The conversion loss of the mixer is 14.6/spl plusmn/0.9 dB over a frequency range of 76-106 GHz. The mixer is pumped by a Iocal oscillator that is tuned over the range of 37.15-52.15 GHz. The IF is kept constant at 1.7 GHz. The new mixer looks attractive for use in broad-band millimeter-wave measuring equipment, such as spectrum analyzers.     

Phase Noise in Millimeter Wave Phase-Locked Loop with Mixer

In order to estimate the phase noise of millimetre wave (MMW) phase-locked oscillator (PLO), the phase noise relation of signals in MMW phase-locked loop (PLL) with frequency conversion is analyzed. The signals include output of MMW PLO, intermediate frequency (IF) output of harmonic mixer and output of microwave oscillator serving as local oscillator (LO). A method to estimate the phase noise of MMW PLO is presented, which is based on the phase noise of LO and IF. At the same time, a W-band PLO is achieved, and the phase noise values of the three signals are measured. It is shown that the experimental result is well coincident with the analysis of phase noise relation.     

Monolithic SiGe Up‐/Down‐Conversion Mixers with Active Baluns

The purpose of this paper is to describe the implementation of monolithically matching circuits, interface circuits, and RF core circuits to the same substrate. We designed and fabricated on‐chip 1 to 6 GHz up‐conversion and 1 to 8 GHz down‐conversion mixers using a 0.8 µm SiGe hetero‐junction bipolar transistor (HBT) process technology. To fabricate a SiGe HBT, we used a reduced pressure chemical vapor deposition (RPCVD) system to grow a base epitaxial layer, and we adopted local oxidation of silicon (LOCOS) isolation to separate the device terminals. An up‐conversion mixer was implemented on‐chip using an intermediate frequency (IF) matching circuit, local oscillator (LO)/radio frequency (RF) wideband matching circuits, LO/IF input balun circuits, and an RF output balun circuit. The measured results of the fabricated up‐conversion mixer show a positive power conversion gain from 1 to 6 GHz and a bandwidth of about 4.5 GHz. Also, the down‐conversion mixer was implemented on‐chip using LO/RF wideband matching circuits, LO/RF input balun circuits, and an IF output balun circuit. The measured results of the fabricated down‐conversion mixer show a positive power conversion gain from 1 to 8 GHz and a bandwidth of about 4.5 GHz.     

Low phase noise heterojunction bipolar transistor oscillator

A low phase noise, heterojunction bipolar transistor (HBT) oscillator has been designed and fabricated for operation at X-band. The common emitter oscillator employs a high-Q dielectric resonator as the parallel feedback element between the base and collector terminals. Series capacitive feedback is used in the emitter to enhance the oscillator's negative output impedance. Single-sideband FM noise levels of -76 dBc/Hz and -102 dBc/Hz have been achieved at 1 kHz and 10 kHz frequency offsets, respectively, for an 11.06 GHz carrier frequency. This is one of the lowest phase noise levels ever reported for an X-band solid-state transistor oscillator.<>     

A 0.5–7.5 GHz Ultra Low-Voltage Low-Power Mixer Using Bulk-Injection Method by 0.18- μm CMOS Technology

A fully differential low-voltage low-power downconversion mixer using a TSMC 0.18-mum CMOS logic process is presented in this letter. The mixer was designed with a four-terminal MOS transistor, the radio-frequency (RF) and local-oscillator signals apply to the gate and bulk of the device, respectively while the intermediate frequency (IF) signals output was from the drain. The mixer features a maximum conversion gain of 5.7dB at 2.4 GHz, an ultra low dc power consumption of 0.48 mW, a noise figure of 15 dB, and an input IP of 5.7 dBm. Moreover, the chip area of the mixer core is only 0.18 times 0.2 mm². The measured 3-dB RF frequency bandwidth is from 0.5 to 7.5 GHz with an IF of 100 MHz, and it is greatly suitable for low-power in wireless communication.     

One-chip GaAs monolithic frequency converter operable to 4 GHz

The frequency converter combines a feedback amplifier, a differential amplifier, a double-balanced mixer, a voltage-controlled oscillator, and an IF amplifier on a 1-mm² GaAs chip. The FET circuits were matched by digital IC design rather than by the distributed element network technique, to use the substrate more effectively. Self-aligned WSi/Au gates 1.5 μm long were used, and the resistance in conventional WSi gates was reduced to enhance microwave characteristics. At 4 GHz, the conversion gain is 18 dB, the double-sideband noise is 11.8 dB and the output power is 5.6 dBm     

45 GHz active HEMT mixer

A low-noise 45 GHz mixer has been realised using a high electron mobility transistor (HEMT). This is the first reported active mixer above 30 GHz and the first reported HEMT mixer. The mixer exhibits 1.5 dB maximum gain at 4 dBm local oscillator (LO) power and 8.1 dB noise figure, including a 2.6 dB NF IF amplifier, at 2 dBm LO power.     

A 22-GHz-band low-noise down-converter for satellite broadcastreceivers

A simple low-cost and high-performance 22 GHz band down-converter developed for a direct-to-home satellite broadcasting system is discussed. The down-converter consists of a low-noise high electron mobility transistor (HEMT) preamplifier, an image recovery mixer with a particular structure using dielectric resonator filters, a 21.4 GHz GaAs FET oscillator stabilized by a dielectric resonator, and an IF amplifier. These components are fully integrating using microwave integrated circuit technology into a small size. A total noise figure of less than 2.8 dB is obtained over the 22.5-23.0 GHz frequency range. The local oscillator achieves a frequency variation of less than 600 kHz_p-p over a temperature range of -20° to +60°C     

Development of a 385–500 GHz Sideband-Separating Balanced SIS Mixer

A submillimeter (385–500 GHz) low-noise sideband-separating balanced SIS (Superconductor Insulator Superconductor) mixer (Balanced 2SB mixer) with high IRR (Image Rejection Ratio) has been successfully developed, whose SSB (Single SideBand) noise temperature is ～ 200 K (10hf/k) with an image rejection ratio of ≥?～10 dB. Balanced mixers have become a promising technology which would break through the limitation especially in terahertz receivers and heterodyne arrays. However, though there are examples in microwave with relatively worse noise performance, submillimeter and terahertz balanced mixers have rarely been developed in spite of their astronomical importance. The developed balanced 2SB mixer is not only the first one demonstrated at submillimeter frequency range, but also has very low noise, high IRR, wide detectable frequencies (385–500 GHz), and a flat IF output spectrum. The balanced 2SB mixer is composed of three RF hybrids, four DSB (Double SideBand) mixers, two 180° IF hybrids, and an IF quadrature hybrid. Several important performance indicators such as noise temperature, IRR, required LO (Local Oscillator) power, and IF spectra were measured. The measured LO power required for the balanced 2SB mixer was typically ~ 14 dB less than that of the single-ended mixers.     

Noise in RF-CMOS mixers: a simple physical model

Flicker noise in the mixer of a zero- or low-intermediate frequency (IF) wireless receiver can compromise overall receiver sensitivity. A qualitative physical model has been developed to explain the mechanisms responsible for flicker noise in mixers. The model simply explains how frequency translations take place within a mixer. Although developed to explain flicker noise, the model predicts white noise as well. Simple equations are derived to estimate the flicker and white noise at the output of a switching active mixer. Measurements and simulations validate the accuracy of the predictions, and the dependence of mixer noise on local oscillator (LO) amplitude and other circuit parameters     

380GHz 辐射计前端关键技术研究

辐射计是一种用于测量物体热辐射的高灵敏度接收机,是被动微波遥感的主要工具。辐射计前端作为辐射计系 统的重要组成部分,其性能直接影响系统的指标。本文介绍一种380GHz 辐射计前端关键技术的设计,包括380GHz 分谐 波混频器及作为本振驱动的190GHz 三倍频器。其中380GHz 分谐波混频器在2.5~3.5GHz 中频输出频率范围内实测变频 损耗低于10dB,均值为9dB;等效噪声温度达到1300K,均值约为2000K。190GHz 三倍频器已完成仿真设计,在190GHz 频率点倍频效率大于25%,输出功率约18mW,在183~193GHz 的频带范围内,输出功率大于5mW。     

12-GHz-Band GaAs Dual-Gate MESFET Monolithic Mixers

12-GHz-band GaAs dual-gate MESFET monolithic mixers have been developed for use in direct broadcasting satellite receivers. In order to reduce chip size, a buffer amplifier has been connected directly after a mixer IF port, instead of employing an IF matching circuit. The mixer and the buffer were fabricated on separate chips, so that individual measurements could be achieved. Chip size is 0.96X 1.26 mm for the mixer and 0.96X0.60 mm for the buffer. A dual-gate FET for the mixer, as well as a single-gate FET for the buffer, has a closely spaced electrode structure. Gate length and width are 1 µm and 320 µm, respectively. The mixer with the buffer provides 2.9+-0.4-dB conversion gain with 12.3+-0.3dB SSB noise figure in the 11.7-12.2-GHz RF band. Local oscillator (LO) frequency is 10.8 GHz. A low-noise converter was constructed by connecting a monolithic preamplifier, an image rejection filter, and a monolithic IF amplifier to the mixer. The converter provides 46.8+-1.5-dB conversion gain with 2.8+-0.2-dB SSB noise figure in the same frequency band.     

Design and measurements of a novel subharmonically pumpedmillimeter-wave mixer using two single planar Schottky-barrier diodes

A novel design of a subharmonically pumped millimeter-wave mixer operating at room temperature was developed and realized. The double sideband conversion loss and mixer noise temperature were measured to be 6.2 dB and 930 K, respectively, at a local oscillator frequency of 73 GHz and an IF of 1.5 GHz. These results are comparable to the best published results measured for subharmonically pumped mixers at similar frequencies. The mixer shows good performance even at IF's up to 9.5 GHz resulting in a useful RF range from 136 GHz to 156 GHz. For the first time a subharmonically pumped millimeter-wave mixer was designed without the use of any scale model measurements or other high-frequency measurements. The whole design process occurred on the basis of computer simulations. Two single low-capacitance planar air-bridge type Schottky-barrier diodes are used as the mixing elements     

An Active IF Balun for a Doubly Balanced Resistive Mixer

In this letter, we present a wideband active intermediate frequency (IF) balun for a doubly balanced resistive mixer implemented using a 0.5 mum GaAs pHEMT process. The 0.3 times 0.5 mm² IF balun was realized through a DC-coupled differential amplifier in order to extend IF frequency of the mixer to DC. The measured amplitude and phase imbalances were less than 1 dB and 5deg, respectively, from DC to 7 GHz. The output third order intercept (OIP3) and P1 dB of the IF balun were 18 dBm and 6 dBm, respectively at 1 GHz. The mixer with the IF balun is 1.7 times 1.8 mm² in size, has a conversion loss of 2 to 8 dB from 8 to 20 GHz RF frequency at a fixed IF of 1 kHz, which proves the mixer operates successfully at an IF frequency close to DC. The measured OIP3 were +10 to +15 dBm over the operating frequency with a DC power consumption of 370 mW.     

Noise and mixing properties of high-Tc Josephson junctions at W-band frequencies

We report on the noise and Josephson mixing properties of high-T_c superconductor (HTS) Josephson junctions. Direct radiation measurements and heterodyne mixing experiments in the frequency range 45–141 GHz have been performed by using YBa₂Cu₃O_7−x (YBCO) step-edge junctions (SEJ) on LaAlO₃ and MgO and bicrystal junctions (BCJ) on MgO substrates. Junctions with current voltage characteristics (CVC) close to predictions of the resistivity shunted junction (RSJ) model were mounted into a high sensitive radiometer system. From linewidth measurements we calculated an effective noise temperature of our junctions. In heterodyne mixing experiments we obtained conversion efficiencies around −14 dB in the 11 GHz intermediate frequency (IF) band under the radiation of two monochromatic signals. In the fundamental mixing regime we observed response at IF at working temperatures up to 72 K. The measured receiver and mixer noise temperature of the Josephson mixer at 94 GHz local oscillator (LO) frequency, an IF of 1.4 GHz and at a working temperature of 10 K was 4700 and 3400 K, respectively.     

A Very Low-Noise Single-Sideband Receiver for 200-260 GHz

A cryogenic Schottky diode mixer receiver has been built for the 230-GHz region with true single-sideband operation and a receiver noise temperature as low as 330 K. Local oscillator power is provided by a frequency tripler, with LO injection and sideband filtering accomplished through quasi-optical interferometers. The image sideband is terminated in a cryogenic load with an effective temperature of 33 K. The IF bandwidth is 600 MHz with nearly flat noise, and the RF band is nearly flat over 50 GHz using backshort tuning of the mixer.     

A subharmonic self-oscillating mixer with integrated antenna for60-GHz wireless applications

A balanced integrated-antenna self-oscillating mixer at 60 GHz is presented in this paper. The modal radiation characteristics of a dual-feed planar quasi-Yagi antenna are used to achieve RF-local oscillator (RF-LO) isolation between closely spaced frequencies. The balanced mixer is symmetric, inherently broad band, and does not need an RF balun. Pseudomorphic high electron-mobility transistors are used in a 30-GHz push-pull circuit to generate the second harmonic and a 30-GHz dielectric resonator was used to stabilize the fundamental oscillation frequency. This allows the possibility of building a balanced low-cost self-contained antenna integrated receiver with low LO leakage for short-range narrow-band communication. Phase locking can be done with half of the RF frequency. The circuit exhibits a conversion loss less than 15 dB from 60 to 61.5 GHz, radiation leakage of -26 dBm at 60 GHz, and IF phase noise of -95 dBc/Hz at 100-kHz offset