L.C.T. Liu

Broadband monolithic passive baluns and monolithic double-balanced mixer

The design and fabrication of four broadband monolithic passive baluns including CPW Marchand, multilayer MS Marchand, planar-transformer and broadside-coupled line baluns are presented. Operational frequencies range from 1.5 GHz to 24 GHz. Maximum relative bandwidths in excess of 3:1 are achieved. Simulated performances using full wave electromagnetic analysis are shown to agree with the measured results. Two accurate equivalent circuit models constructed from either electromagnetic simulated or measured S-parameters are developed for the MS Marchand and transformer baluns making the optimization of baluns and circuit design using the baluns much more efficient. The design of monolithic double-balanced diode mixer using two planar-transformer baluns is also presented. Without DC bias, the mixer shows a minimum conversion loss of 6 dB with the RF at 5 GHz and a LO drive of 15 dBm at 4 GHz. The measured input IP/sub 3/ of this mixer is better than 15 dBm over the 4 to 5.75 GHz frequency band. >

A W-band monolithic downconverter

The design, fabrication, and evaluation of a fully integrated W-band monolithic downconverter based on InGaAs pseudomorphic HEMT technology are presented. The monolithic downconverter consists of a two-stage low-noise amplifier and a single-balanced mixer. The single-balanced mixer has been designed using the HEMT gate Schottky diodes inherent to the process. Measured results of the complete downconverter show conversion gain of 5.5 dB and a double-sideband noise figure of 6.7 dB at 94 GHz. Also presented is the downconverter performance characterized over the -35 degrees C to +65 degrees C temperature range. The downconverter design was a first pass success and has a high circuit yield. >

An ultra low noise W-band monolithic three-stage amplifier using 0.1- mu m pseudomorphic InGaAs/GaAs HEMT technology

An ultra-low-noise W-band monolithic three-stage amplifier based on 0.1- mu m pseudomorphic InGaAs/GaAs high electron mobility transistor (HEMT) devices has been developed. This amplifier has a measured noise figure of 3.5 dB with an associated small signal gain of 21 dB at 94 GHz. This is the best reported performance of a monolithic W-band high-gain low-noise amplifier (LNA), significantly improved compared with previous records in terms of noise figure and associated gain. Accurate modeling techniques were essential to the success of this monolithic circuit design, which included active device and full-wave electromagnetic analysis of passive matching structures. The measured results of the W-band three-stage monolithic microwave integrated circuit (MMIC) LNA from 91 to 97 GHz are presented.<<ETX>>

A 30 GHz Monolithic Receiver

Several monolithic integrated circuits have been developed to make a 30-GHz receiver. The receiver components include a low-noise amplifier, an IF amplifier, a mixer, and a phase shifter. The LNA has a 7-dB noise figure with over 17 dB of associated gain. The IF amplifier has a 13-dB gain with a 30-dB control range. The mixer has a conversion loss of 10.5 dB. The phase shifter has a 180° phase shift control and a minimum insertion loss of 1.6 dB.

Broadband single- and double-balanced resistive HEMT monolithic mixers

A double-balanced (DB) 3-18 GHz and a single-balanced (SB) 2-16 GHz resistive HEMT monolithic mixer have been successfully developed. The DB mixer consists of a AlGaAs/InGaAs HEMT quad, an active LO balun, and two passive baluns for RF and IF. At 16 dBm LO power, this mixer achieves the conversion losses of 7.5-9 dB for 4-13 GHz RF and 7.5-11 dB for 3-18 GHz RF. The SB mixer consists of a pair of AlGaAs/InGaAs HEMTs, an active LO balun, a passive IF balun and a passive RF power divider. At 16 dBm LO power, this mixer achieves the conversion losses of 8-10 dB for 4-15 GHz RF and 8-11 dB for 2-16 GHz RF. The simulated conversion losses of both mixers are very much in agreement with the measured results. Also, the DB mixer achieves a third-order input intercept (IP/sub 3/) of +19.5 to +27.5 dBm for a 7-18 GHz RF and 1 GHz IF at a LO drive of 16 dBm while the SB mixer achieves an input IP/sub 3/ of +20 to +28.5 dBm for 2 to 16 GHz RF and 1 GHz IF at a 16 dBm LO power. The bandwidth of the RF and LO frequencies are approximately 6:1 for the DB mixer and 8:1 for the SB mixer. The DB mixer of this work is believed to be the first reported DB resistive HEMT MMIC mixer covering such a broad bandwidth. >

High performance resistive EHF mixers using InGaAs HEMTs

The design, fabrication, and testing of a hybrid and a monolithic single-balanced EHF mixer are presented. Very low mixer intermodulation distortion was achieved using a 0.2- mu m*160- mu m pseudomorphic InGaAs high-electron-mobility transistor (HEMT) biased in the resistive mode. Both mixers show similar excellent measured performance. Mixer conversion loss over the 26-29 GHz RF frequency band is about 7-9 dB for DC to 2 GHz IF (intermediate frequency) frequencies. With an LO (local oscillator) power of +13 dBm, the measured input two-tone third-order intercept point is higher than +24 dBm.<<ETX>>

A double balanced 3-18 GHz resistive HEMT monolithic mixer

A double balanced (DB) 3-18 GHz resistance HEMT (high electron mobility transistor) monolithic mixer has been successfully developed. This mixer consists of a AlGaAs/InGaAs HEMT quad, an active LO (local oscillator) balun, and two passive baluns, RF and IF (intermediate frequency). At 16 dBm LO power, this mixer achieves the conversion losses of 7.5-9 dB for 4-14 GHz RF and 7.5-11 dB for 3-18 GHz RF. The simulated conversion loss is very much in agreement with the measured results. Also, a third-order input intercept of +26 dBm is achieved for a 10-11 GHz RF and 1 GHz IF at a LO drive of 16 dBm. The design is believed to be the first DB resistive HEMT MMIC (monolithic microwave integrated circuit) mixer covering up to 6:1 bandwidth.<<ETX>>

Method for fabricating a radio frequency integrated circuit and product formed thereby

A method of designing and fabricating a semiconductor integrated circuit for operation at radio frequencies. The method includes fabricating an integrated circuit having circuit components, at least one of which is an active device, testing the electrical performance of at least one of the active devices and then forming an electrical conductor to the integrated circuit to interconnect selected ones of the circuit components to form a radio frequency circuit, wherein the selection is based on the outcome of the electrical performance test.

Production Technology for High-Yield, High-Performance GaAs Monolithic Amplifiers

A production technology for GaAs MMICs has been developed. In a six-month period, seventy 2-in wafers have been processed for X-band monolithic power and low-noise amplifiers and more than 2000 working chips have been produced. The two-stage power amplifiers have achieved a typical performance of 1.6-w output power with 8-dB associated gain and 20-percent power-added efficiency at 9.5 GHz. The two-stage low-noise amplifiers have consistently achieved 3-dB noise figure with 20-dB associated gain at the same frequency. Improvement of MMIC processing technology implemented in this work has resulted in an average dc chip yield of 15 percent.

A K-band HEMT low noise receive MMIC for phased array applications

A state-of-the-art InGaAs HEMT (high electron mobility transistor) receive MMIC (microwave monolithic integrated circuit) consisting of a low-noise amplifier and a novel 3-bit phase shifter has been fabricated and evaluated for receive phased-array development at 20 GHz. The low-noise amplifier employs series and shunt feedback to provide high gain and low noise performance while the 3-bit phase shifter utilizes a novel switched-allpass approach to minimize circuit size. The monolithic receive chip has demonstrated noise figures of less than 2.75 dB and gains between 11.8 and 14.1 dB for the 8 phase-shift states across the 20.2-21.2 GHz frequency range.<<ETX>>