Chinchun Meng

Monolithic Broadband Gilbert Micromixer With an Integrated Marchand Balun Using Standard Silicon IC Process

A single-ended wideband downconversion Gilbert micromixer is demonstrated in this paper using 0.35-mum SiGe BiCMOS technology. A transimpedance amplifier with resistive feedback is utilized in the IF stage while a broadband Marchand balun is employed to generate wideband differential local oscillator signals. The planar Marchand balun topology employed in this paper can generate truly balanced signals even in the presence of the lossy low-resistivity (~10 Omegamiddotcm) silicon substrate. A systematic approach to measure the frequency response of each individual stage in a Gilbert mixer is developed in this paper. This single-ended wideband mixer has the conversion gain of 15 dB, IP1dB of -19 dBm, IIP3 of -7 dBm, and the noise figure of 13 dB. The mixer works from 3.5 to 14.5 GHz

The origin of the kink phenomenon of transistor scattering parameter S/sub 22/

A novel theory based on dual-feedback circuit methodology is proposed to explain the kink phenomenon of transistor scattering parameter S/sub 22/. Our results show that the output impedance of all transistors intrinsically shows a series RC circuit at low frequencies and a parallel RC circuit at high frequencies. It is this inherent ambivalent characteristic of the output impedance that causes the appearance of kink phenomenon of S/sub 22/ in a Smith chart. It was found that an increase of transistor transconductance enhances the kink effect while an increase of drain-to-source (or collector-to-emitter) capacitance obscures it. This explains why it is much easier to see the kink phenomenon in bipolar transistors, especially heterojunction bipolar transistors, rather than in field-effect transistors (FETs). It also explains why the kink phenomenon is seen in larger size FETs and not in smaller size FETs. Our model not only can predict the behavior of S/sub 22/, but also calculate all S-parameters accurately. Experimental data of submicrometer gate Si MOSFETs and GaAs FETs are used to verify our theory. A simple method for extracting transistor equivalent-circuit parameters from measured S-parameters is also proposed based on our theory. Compared with traditional Z- or Y-parameter methods, our theory shows another advantage of giving deep insight into the physical meaning of S-parameters.

Analysis, design, and optimization of InGaP-GaAs HBT matched-impedance wide-band amplifiers with multiple feedback loops

The realization of matched impedance wide-band amplifiers fabricated by InGaP-GaAs heterojunction bipolar transistor (HBT) process is reported. The technique of multiple feedback loops was used to achieve terminal impedance matching and wide bandwidth simultaneously. The experimental results showed that a small signal gain of 16 dB and a 3-dB bandwidth of 11.6 GHz with in-band input/output return loss less than -10 dB were obtained. These values agreed well with those predicted from the analytic expressions that we derived for voltage gain, transimpedance gain, bandwidth, and input and output impedances. A general method for the determination of frequency responses of input/output return losses (or S/sub 11/, S/sub 22/) from the poles of voltage gain was proposed. The intrinsic overdamped characteristic of this amplifier was proved and emitter capacitive peaking was used to remedy this problem. The tradeoff between the input impedance matching and bandwidth was also found.

GaInP/GaAs HBT Sub-Harmonic Gilbert Mixers Using Stacked-LO and Leveled-LO Topologies

This paper discusses and demonstrates the most popular sub-harmonic Gilbert mixers in 2-mum GaInP/GaAs HBT technology. High two local oscillators (2LO)-to-RF isolation is important to alleviate the self-mixing problem of the sub-harmonic mixer. The demonstrated GaInP/GaAs HBT stacked-local oscillator (LO) mixer topology has achieved the best 2LO-to-RF isolation when compared with the previous literature. On the other hand, the leveled-LO sub-harmonic mixers have advantages in terms of the high speed and low dc supply voltage at the cost of much larger LO pumping power. Among all the structures, the bottom-LO sub-harmonic mixer has the lowest current consumption and the simplest circuit structure at the expense of the 2LO-to-RF isolation

60-GHz Dual-Conversion Down-/Up-Converters Using Schottky Diode in 0.18

Due to the benefits of Schottky diodes, 0.18-μm CMOS technology is being promoted for millimeter wave applications. In this paper, 60-GHz dual-conversion down-/up-converters using Schottky diodes are realized by using 0.18-μm foundry CMOS technology. A CoSi2-Si Schottky diode, fabricated on a lower doped N-well by blocking the threshold voltage adjustment implant, has a lower reverse leakage current and a better ideality factor. Thus, it is ideal for the 60-GHz sub-harmonic mixer design. Two new types of Schottky-diode mixers, a down-conversion sub-harmonic mixer with a dual-band lump-distributed phase-inverter rat-race coupler and an up-conversion sub-harmonic mixer with a trifilar transformer, are realized and employed at the high-frequency conversion stage of the dual-conversion architecture to achieve small size and broadband isolations. The silicon-based Schottky diode with a low turn-on voltage offers great advantage in LO pumping power, especially for an antiparallel diode pair structure. In our Schottky-diode sub-harmonic mixers, the required LO power is only 1 dBm. The dual-conversion down-converter achieves 5-dB conversion gain and 19 dB noise figure under Vdd=2.5 V and Idd=22 mA, and the dual-conversion up-converter, with Vdd=2.5 V and Idd=26 mA, attains greater than 40-dB sideband rejection and -1 dB conversion gain over the whole 60-GHz bandwidth.

\mu{\hbox {m}}

A K-band sub-harmonically pumped resistive mixer is demonstrated using standard 0.13 mum CMOS technology. A miniature Marchand Balun is integrated with the resistive mixer to generate equal amplitude and out-of-phase signals for mixers local oscillation (LO) port directly on the lossy silicon substrate. The sub-harmonic resistive mixer with the integrated Marchand balun has conversion loss of 11-12 dB at fIF = 100 MHz and PLO = 7 dBm for RF frequencies from 18 to 26 GHz. The LO-RF and LO-IF isolations are approximately 30 and 33 dB, respectively.

Foundry CMOS Technology

In this paper, we have developed an interpretation of transistor S-parameters by poles and zeros. The results from our proposed method agreed well with experimental data from GaAs FETs and Si MOSFETs. The concept of source-series feedback was employed to analyze a transistor circuit set up for the measurement of the S-parameters. Our method can describe the frequency responses of all transistor S-parameters very easily and the calculated S-parameters are scalable with device sizes. It was also found that the long-puzzled kink phenomenon of S/sub 22/ observed in a Smith chart can be explained by the poles and zeros of S/sub 22/.

K-Band CMOS Sub-Harmonic Resistive Mixer With a Miniature Marchand Balun on Lossy Silicon Substrate

A 2.4/5.7-GHz dual-band Weaver-Hartley architecture, using 0.18-mum CMOS technology, is demonstrated in this paper. The 2.4-GHz signal is set to be the image signal when the desired signal is at 5.7 GHz, and vice versa. Since the Weaver and Hartley systems are combined into this architecture, the demonstrated architecture rejects not only the first image signal, but also the secondary image signal. The image-rejection ratios of the first image signal and the secondary image signal are better than 40 and 46 dB, respectively. In this paper, a diagrammatic explanation is employed to obtain the image-rejection mechanisms of the Weaver-Hartley architecture.

A novel interpretation of transistor S-parameters by poles and zeros for RF IC circuit design

The low-phase-noise GaInP/GaAs heterojunction bipolar transistor (HBT) quadrature voltage controlled oscillator (QVCO) using transformer-based superharmonic coupling topology is demonstrated for the first time. The fully integrated QVCO at 4.87GHz has phase noise of -131dBc/Hz at 1-MHz offset frequency, output power of -4dBm and the figure of merit (FOM) -198dBc/Hz. The state-of-the-art phase noise FOM is attributed to the superior GaInP/GaAs HBT low-frequency device noise and the high quality transformer formed on the GaAs semi-insulating substrate.

2.4/5.7-GHz CMOS Dual-Band Low-IF Architecture Using Weaver–Hartley Image-Rejection Techniques

CMOS deep n-well technology can eliminate body effects of NMOS transistors and improve LO-IF and LO-RF isolation in a Gilbert micromixer. A 37 dB LO-IF and 38 dB LO-RF isolation downconversion micromixer with 19 dB conversion gain, IP/sub 1dB/=-19.5 dBm and IIP/sub 3/=-12.5 dBm when RF=2.4 GHz and LO=2.25 GHz is demonstrated in this paper by using 0.18 /spl mu/m deep n-well CMOS technology. The input return loss and output return loss are better than 15 dB for frequencies up to 6 GHz. On the other hand, a downconversion micromixer without deep n-well has almost identical power performance but achieves only 20 dB LO-IF isolation and 21 dB LO-RF isolation even if two kinds of mixers are fabricated in adjacent areas of the same wafer. The downconversion micromixer used here has an intrinsically single-to-differential input stage and active differential PMOS loads to increase IF differential gain while CMFB is used to stabilize bias points. An IF differential amplifier converts differential output into a single-ended output. Finally, an off-chip rat-race coupler provides balanced LO signals to facilitate isolation measurement.