Design of Stable, Very Low Noise, Cavity-Stabilized IMPATT Oscillators for C Band

Two types of C-band IMPATT oscillators, which easily meet the noise and stability requirements for use as local oscillators in microwave FM communications equipment, are described. Both types use a transmission cavity-stabilization circuit as proposed by Kurokawa. In one of them a TE/sub 103/ mode rectangular invar cavity is used for stabilization, while in the other the coupling is made via a high-Q cylindrical TE/sub 011/, mode cavity. Although the Si IMPATT diode is inherently noisy, it is shown that a proper choice of circuit parameters and diode characteristics leads to measured FM noise levels of less than 0.2 Hz in a 100-Hz band. With respect to frequency stability, special attention is paid to hysteresis-free compensation of temperature effects and to the influence of changes with time and ambient temperature of the diode and of the internal atmosphere of the cavity. By careful processing and sealing, an average temperature stability of better than -0.4 ppm//spl deg/C was realized with temperature cycling between 26 and 51/spl deg/C over a period of 450 h.     

High-Power 50-GHz Double-Drift-Region IMPATT Oscillators with Improved Bias Circuits for Eliminating Low-Frequency Instabilities

Low-frequency instabilities in millimeter-wave double-drift-region (DDR) IMPATT diodes are investigated and new oscillator circuits with the improved bias circuits for eliminating the low-frequency instability are developed. DDR IMPATT diodes mounted in these circuits exhibited a maximum free-running oscillation power of 1.6 W at 55.5 GHz with 11.5-percent conversion efficiency. A highly stabilized oscillator was also constructed with the maximum output power of 1 W and the frequency stabflity 0.3 ppm/mA at 51.86 GHz.     

A 26-GHz High-Performance MIC Transmitter/Receiver for Digital Radio Subscriber Systems

A high-performance 26-GHz microwave integrated circuit (MIC) transmitter/receiver using frequency-shift-keying (FSK) modulation has been developed. All RF components are fabricated using MIC technology and integrated into a single compact module. Newly developed MIC components include an FSK modulator, a time division multiple access (TDMA) switch, and a single-balanced mixer. The FSK modulator is composed of an IMPATT diode, a varactor diode, and a dielectric resonator. A high-frequency stability of 50 ppm is obtained in the tempera-ture range of -10-45°C. The configuration and performance of the TDMA switch with a high ON/OFF ratio and a low insertion loss are described, A transmitting power of 21 dBm and a receiving noise figure of 8.7 dB are obtained. The bit error rate is measured to evaluate the overall transmitter/receiver performance. The required carrier-to-noise ratio (CNR) has been considerably improved by adopting FSK modulation and by using the MIC transmitter/receiver described in this paper.     

Composite IMPATT diodes for 110-GHz operation

The assembly of composite silicon IMPATT diodes for 110-GHz operation with improved power-handling capability is described. Up to 140 mW CW output power at burnout was observed with a three-wafer assembly compared with 110 mW and 74 mW for the best performing double- and single-wafer units, respectively. The efficiencies were approximately 3 percent.     

Noise in IMPATT Diode Amplifiers and Oscillators

The results of experimental and theoretical investigations of the noise characteristics of lMPATT diode amplifiers and oscillators are presented. The oscillator noise is shown to consist of three different contributions: modulation noise, selectively amplified primary noise, and conversion noise. The influence of the active device nonlinearity and load circuit parameters is discussed in detail. The experimental results are in good agreement with the theoretical predictions. It is especially pointed out that the large correlation between AM and FM fluctuations, usually measured in IMPATT oscillators, indicates nonoptimum AM noise performance. Experimental techniques for achieving optimum AM noise performance are demonstrated (orthogonal noise tuning). By a simple extension of the model, the noise behavior of an injection phase-locked oscillator can be described. The calculated AM and FM noise power spectra for the synchronized oscillator are also shown to be in good agreement with experimental results. Finally the signal-to-noise ratio for current modulated IMPATT oscillators is investigated and optimization is demonstrated.     

Millimeter IMPATT Sources for the 130-170-GHz Range

Device and circuit design of silicon IMPATT sources in the 130-170-GHz range is discussed. A 170-GHz source has been developed with 16 mW at the isolator output having an AM double-side-band noise-to-signal ratio of -115 dB per 1 kHz beyond 70 kHz from carrier.     

Ku波段振荡用GaAs场效应晶体管

本文讨论GsAs FET振荡应用时的工作原理、设计考虑。Ku波段振荡用FET在15GHz下获得60mW输出功率,在18GHz下获得40mW输出功率。     

An Investigation of Parametric Noise in Millimeter-Wave IMPATT Oscillators

The IMPATT oscillator used as an LO source in a receiver has often been found to contribute a large amount of excess noise to the system (sometimes more than 40 dB compared to a klystron). Often the IMPATT noise has been referred to as avalanche noise, but theoretically this should only reduce the carrier-to-noise ratio by 10-15 dB when compared to a klystron. In the following paper, we show that the excess noise far from the carrier frequency (i.e., sideband noise) is much more dependent on parametric oscillations excited below the cutoff frequency of the mount than, on avalanche noise. By modifying the Hines equation for parametric stability, we have been able to investigate the parametric noise properties of realistic millimeter-wave IMPATT oscillators. Using theoretical waveguide models, we have investigated how the sideband noise depends on various mount configurations, avalanche currents, and IMPATT diodes, The calculated curves show good correlation with the measured noise at 4 GHz from the carrier. It often has been found to be very difficult to completely reduce the parametric noise in avalanche oscillators. In these cases, the method of comparison between different mounts presented here for finding the diode-mount configuration which gives least parametric noise can be an aid in the construction of low-noise IMPATT oscillators.     

A 26-GHz Band Integrated Circuit of a Double-Balanced Mixer and Circulators

Integration of a double-balanced mixer and ferrite-disk type circulators have been successfully achieved in the 26-GHz band. The total single-sideband noise figure of the integrated circuit, composed of a mixer and two circulators, is 8.5 dB, including the noise contribution from an IF amplifier. The double-balanced mixer is composed of microstrip lines, slot lines, coupled slot lines, coplanar lines, Au wires, and four beam lead Schottky-barrier diodes. The minimum conversion loss of the mixer is 5.3 dB at a signal frequency of 25.4 GHz. Isolation between RF and LO ports is greater than 30 dB. The ferrite-disk type circulator is produced by a newly developed precise machining technique. The minimum insertion loss of the circulator is 0.45 dB, and the isolation is greater than 20 dB. The integrated circuit with the ferrite-disk type circulators will be extended to the millimeter-wave band.     

Power Amplification for FM and PM Signals with Synchronized IMPATT Oscillators

To meet certain requirements for system performance such as broadening the bandwidth, obtaining a high gain for the FM-and PM-signal amplifier, and increasing the power output, the "locking amplifier" composed of cascade-connected and hybrid-combined synchronizing oscillators is described. How the SNR of the amplifier is greatly improved and its gain increased by cascade connection and hybrid combination is discussed. These have been ascertained by experiments. In addition, another broad-band and high-gain synchronizing circuit and its application to pulse code modulation-phase modulation (PCM-PM) signal amplification are also discussed.     

11-GHz MIC QPSK Modulator for Regenerative Satellite Repeater

An 11-GHz MIC QPSK modulator for a 14/11-GHz, 120-Mbit/s regenerative satellite repeater is described. The modulator consists of cascaded 90° and 180° phase switches, realized with circulators and PIN diodes. The static and the dynamic behavior are presented. It is shown how the bit-error-rate performance is deteriorated by slow switching transients and timing errors.     

High-power generation in IMPATT devices in the 100-200-GHz range

A silicon double-drift IMPATT diode with high uniform doping levels was simulated. Simulation results show that it is possible for silicon IMPATT diodes to generate extremely high pulsed output power for frequencies above 100 GHz under high current-density operation. The highest output power matched to a 1-Ω load resistance obtained at 150 GHz is 37.7 W with a DC current density of 200 kA/cm², although the calculated power conversion efficiency is low. It is also shown that the low-power conversion efficiency limits the diode's continuous wave power operation     

Millimeter-Wave Silicon IMPATT Sources and Combiners for the 110-260-GHz Range

This paper reports recent progress in CVV and pulsed silicon IMPATT sources in the 110-260-GHz frequency range. Pulsed output power levels of 3, 1.3, and 0.7 W, and CW output power levels of 110, 60, and 25 mW have been consistently achieved from single-drift IMPATT diodes at 140, 170, and 217 GHz, respectively. A Read-type IMPATT diode that generated good output power over a wide frequency range was fabricated. A bridged double-quartz standoff package was developed and successfully used for the entire frequency range. Power combiners at center frequencies of 140 and 217 GHz were developed with peak output power of 9.2 and 1 W, respectively.     

Transmit-Receive Multiplexer for the 12-14-GHz Band

A compact low-loss transmit-receive multiplexer for direct satellite broadcast of two television channels is described. The response synthesis for the two contiguous transmit channels is outlined. A circuit model for the filter-to-manifold coupling, methods for its control, and the optimization of the manifold spacings are discussed. A technique for improving the transmitter-to-receiver isolation is shown. Experimental responses are given.     

A New Transceiver Architecture for the 60-GHz Band

A new “half-RF” architecture incorporates a polyphase filter in the signal path to allow the use of a local oscillator frequency equal to half the input frequency. The receiver performs 90 $^{circ}$ phase shift and two downconversion steps to produce quadrature baseband outputs. The transmitter upconverts the quadrature baseband signals in two steps, applies the results to a polyphase filter, and sums its outputs. Each path employs a dedicated 30-GHz oscillator and is fabricated in 90-nm CMOS technology. The receiver achieves a noise figure of 5.7–7.1 dB and gain/phase mismatch of 1.1 dB/2.1$^{circ}$ while consuming 36 mW. The transmitter produces a maximum output level of $-$7.2 dBm and an image rejection of 20 dB while drawing 78 mW.      

Analysis and Design of a Low-Noise X-Band MIC Mixer 1-GHz IF Amplifier

The analysis and design of a low-noise 500-MHz bandwidth MIC image- and sum-enhanced 12-GHz mixer-IF amplifier is described. Typical midband noise figures of 6.3 dB have been achieved.     

Noise characteristics of GaAs and Si IMPATT diodes for 50-GHz range operation

Direct comparison of noise behaviors between GaAs Schottky-barrier junction and Si diffused p⁺-n junction diodes operating in the 50-GHz range is reported by using the same circuitry. In the oscillator operation, the GaAs diode exhibits excess "1/f^m" noise near carrier, whereas the Si diode shows flat spectrum. Far from the carrier, and AM-DSB-NSR of -133 dB in a 100-Hz bandwidth and an FM noise measure of 27.1 dB are observed for GaAs diodes. Corresponding values obtained for Si diodes are -125 and 36.2 dB, respectively. As a reflection amplifier, minimum noise figures of 27.5 and 38 dB are achieved for the GaAs and Si devices, respectively. These results indicate that the GaAs IMPATT is superior in noise behavior to the Si diode also in the 50-GHz frequency range by about 10 dB. It is emphasized that the noise induced in the bias circuit of the IMPATT oscillator is a replica of the sideband noise of the output power and can be used as an indicator to obtain a low-noise tuning condition of the oscillator.     

MMIC 14-GHz VCO and Miller Frequency Divider for Low-Noise Local Oscillators

An MMIC voltage-controlled oscillator and an MMIC frequency divider are developed and applied to a 14-GHz low-noise local oscillator. To obtain both wide tuning range and low pulling figure, the source-follower FET circuit is used in the voltage-controlled oscillator. A wide-band balanced mixer and a filtering amplifier are integrated in a single chip and constitute the Miller frequency divider. -The MMIC's were assembled into a 14-GHz phase-locked loop in order to demonstrate that they will operate as key components of low-noise oscillators. It is shown experimentally that even for low-Q MMIC circuitry, the carrier noise of the oscillator is reduced enough for practical purposes such as space-borne heterodyne receivers, transmitters, and radio repeaters in Ku-band satellite communication systems. Thus, prospects are bright for development of single-chip microwave low-noise oscillators.     

A 0.5-W CW IMPATT diode amplifier for high-capacity 11-GHz FM radio-relay equipment

A stable CW reflection-type Si-IMPATT diode amplifier has been developed as a transmitting high-power amplifier for the 11-GHz-band FM radio-relay system. It is a solid-state 960-channel system with a nominal transmitting power of 500 mW. The circuit design of the amplifier with a unique stabilizing circuit which provides unconditionally stable operation, is described. Also described are the FM noise contributions due to the biasing circuit parameters and experimental results of the FM noise of a locked oscillator and a negative resistance amplifier. Applications of the amplifiers in other frequency bands are described along with data obtained from the amplifiers for use in communication systems.