Byul Hur

Embedded RF Test Circuits: RF Power Detectors, RF Power Control Circuits, Directional Couplers, and 77-GHz Six-Port Reflectometer

Modern integrated circuits (ICs) are becoming an integrated parts of analog, digital, and radio frequency (RF) circuits. Testing these RF circuits on a chip is an important task, not only for fabrication quality control but also for tuning RF circuit elements to fit multi-standard wireless systems. In this paper, RF test circuits suitable for embedded testing are introduced: RF power detectors, power control circuits, directional couplers, and six-port reflectometers. Various types of embedded RF power detectors are reviewed. The conventional approach and our approach for the RF power control circuits are compared. Also, embedded tunable active directional couplers are presented. Then, six-port reflectometers for embedded RF testing are introduced including a 77-GHz six-port reflectometer circuit in a 130 nm process. This circuit demonstrates successful calibrated reflection coefficient simulation results for 37 well distributed samples in a Smith chart. The details including the theory, calibration, circuit design techniques, and simulations of the 77-GHz six-port reflectometer are presented in this paper.

CMOS Programmable Gain Distributed Amplifier With 0.5-dB Gain Steps

A new CMOS programmable gain distributed amplifier with 0.5-dB gain steps is fabricated in a 130-nm process. The circuit is designed to demonstrate broadband (>;1 decade) programmable gains with excellent matching and high isolation for use in RF integrated-circuit testing. The measured slope of S21 loss is approximately 3 dB/decade over frequencies from 0.8 to 9 GHz where input and output return losses are better than roughly 10 dB; the measured input 1-dB compression point and third-order intermodulation intercept point at 2.78 GHz for the maximum 2.5-dB gain is 1 and 12.5 dBm, respectively. The measured noise figure is below 9.5 dB at 9 GHz. The circuit consumes approximately 40 mW total from 3.1-V analog and 1.5-V digital supplies.

Tunable Broadband MMIC Active Directional Coupler

This paper presents a tunable broadband monolithic microwave integrated circuit (MMIC) active directional coupler that demonstrates tuned coupling gains (from 3 dB to -6 dB) and tuned center frequencies. The active directional coupler consists of two broadband near 90° phase shifters, two amplifiers between these phase shifters, and varactors at the connection nodes of the phase shifters and the amplifiers. It was designed and fabricated in a 130-nm process. For a 3-dB coupling gain, the 10-dB directivity bandwidth is 2.3 GHz (from 5.5 to 7.8 GHz). The amplitude imbalance is 3 dB ±0.5 dB, the phase imbalance is 180° ± 5°, and the noise figure is less than 8 dB in the range of 4 to 9 GHz. The return losses are better than 19 dB and the insertion loss is less than 1.2 dB in the range of 4 to 9 GHz. The measured IP1 dBs for 3-dB and 0-dB coupling gains at 6.7 GHz are 0.3 dBm and 1.8 dBm, respectively. The supply voltage is 1.2 V. The measured power consumptions at 3-dB, 0-dB, - 3-dB, and - 6-dB coupling gains are 22 mW, 6 mW, 3 mW, and 1 mW, respectively. The core chip area, including two on-chip DC bias inductors, is 470 μm × 250 μm.

Low-power wireless climate monitoring system with RFID security access feature for mosquito and pathogen research

This paper introduces a low-power wireless climate monitoring system with an RFID security access feature for mosquito and pathogen research. Mosquito-borne diseases, which are critical threats to human health, include malaria, yellow fever, dengue fever, and West Nile Virus. The wireless monitoring system provides environmental data such as temperature, humidity, wind speed, and wind direction. The measured data can be used to predict the habitat of mosquitoes and be used to recommend the amount and location of pesticide application. This paper describes the design and implementation of the low-power wireless climate monitoring system with various environmental sensors, 2.4-GHz wireless module, RFID reader for the security access control, audio system, and a solar charger system. The measured data was received and processed by a custom Windows application. The measured data was available through both desktop and mobile internet browsers and a mobile android application. Five wireless climate monitoring systems were used for multiple field tests. The analysis example of the pseudo climate data for the reduced use of pesticides is also presented.

True-differential/common-mode mixed-mode S-parameter measurement techniques for cellular and 4G bandwidths

This paper introduces true-differential/common-mode mixed-mode S-parameter measurement techniques for cellular and 4G bandwidths. The on-chip differential amplifier is designed in a 130-nm RFCMOS process, where the simulated differential mode S-parameters are also presented over the wide frequencies (0.5 ~ 3.5 GHz) which includes cellular frequencies. The differential gains are 8.4 dB and 7.9 dB at 1 GHz and 3 GHz, respectively. The non-linear effects of the RF circuits can result in mixed-mode S-parameter measurement errors in virtual differential mode. Because real differential and common mode input signals stimulate a DUT in true differential mode, true differential/common mode measurements may reduce the measurement errors caused by the non-linear effects. Differential/common mixed-mode S-parameter tests were performed using an AD8350 IC from 0.1 GHz to 2.0 GHz. The various comparisons of measured input P1dB compression points and common mode rejection ratio (CMRRs) in true and virtual differential modes are presented.

Progress in development of the low-power wireless multiple temperature sensor pole for pesticide, agriculture, and mosquito research

This paper introduces the development progress of a wireless multiple temperature sensor pole. It can be applicable to pesticide, agriculture, and mosquito research. Monitoring multiple soil and air temperatures at different heights and depths can provide useful data to various fields of study and research. The proposed wireless multiple temperature sensor pole can measure four temperatures that are two air temperatures and two soil temperatures at different heights and depths. The wireless temperature sensor pole is about 10 feet tall with a 3.3-feet distance between temperature sensors. The temperature sensor pole electronic device incudes four temperature sensors and a 2.4-GHz wireless module. The measured data can be processed by a custom Windows application. The data can be accessed through PC and mobile internet browsers and an android application. Measurements in the field using five temperature sensor poles were carried out. The measurement results provide useful information for pesticide, agriculture, and mosquito research areas.

Automated wideband test system, measurement uncertainty, and design of on-chip six-port reflectometers for 5G applications

This paper introduces an automated wideband test system, measurement uncertainty, and designs of on-chip six-port reflectometers (SPRs) that can be used for 5G applications. The trial frequency bands of 5G technology research and development (R&D) include 15 GHz, 28 GHz, and 38 GHz. Reflection measurements at these high frequencies are an essential part of 5G R&D. A six-port reflectometer (SPR) can be used for the embedded reflection measurements. However, the complexity of its calibration makes measurements challenging. Performing multiple measurements at wideband frequencies is even more challenging. An automated test system of on-chip SPRs in this paper can alleviate this problem. The details of the automated test system are introduced. Automated measurements were performed from 12 GHz to 18 GHz, including 15 GHz. The discussion of the measurement uncertainty is included. The design, layout, and simulation results of a 28-GHz SPR are also presented.

CMOS Broadband Programmable Gain Active Balun With 0.5-dB Gain Steps

This paper presents a CMOS broadband programmable gain active balun (PGAB) that demonstrates seven digitally controlled gains with 0.5-dB gain steps separately for plus and minus output ports. The PGAB was designed and fabricated in a 130-nm RFCMOS process. For the maximum gain state, the measured gains of the plus and minus ports are 0.0 and 1.1 dB at 2 GHz. The operating frequency range is from 1.0 to 8.0 GHz by 0.3-dB gain step error, and it is from 1 to 13.0 GHz by 3-dB gain attenuation. For the maximum gain state, the measured amplitude imbalance and phase imbalance from 1 to 16 GHz are less than 1.4 dB and 4.1 °, respectively. The measured input return losses are better than 13.5 dB, and the output return losses are better than 18.5 dB for all controlled gain states from 1 to 16 GHz. The measured IP1dB at 7 GHz is 6.1 dBm. The measured noise figures for the plus and minus ports from 2 to 14 GHz are less than 11.2 and 10.2 dB, respectively. The supply voltages are 3.0 and 1.5 V, and the measured power consumption is 93 mW. The core area of the fabricated integrated circuit is 0.38 mm × 0.36 mm.