Abhilash Goyal

A novel self-healing methodology for RF amplifier circuits based on oscillation principles

This paper proposes a new self-healing methodology for embedded RF amplifiers in RF sub-systems. The proposed methodology is based on oscillation principles in which the device-under-test (DUT) generates its test signature with the help of additional circuitry. In the proposed methodology, the self-generated test signature from the RF amplifier is analyzed by using on-chip resources for testing and controlling its calibration knobs to compensate for multi-parameter variations in the manufacturing process. Thus, the proposed methodology enables self-test and self-calibration/correction of RF amplifiers without the need for an external test stimulus, enabling true self-healing RF designs. The proposed methodology is demonstrated through simulations as well as measurements performed on an RF LNA, which were designed in a commercially-available SiGe BiCMOS process technology.

A New Self-Healing Methodology for RF Amplifier Circuits Based on Oscillation Principles

This paper proposes a novel self-healing methodology for embedded RF Amplifiers (LNAs) in RF sub-systems. The proposed methodology is based on oscillation principles in which the Device-under-Test (DUT) itself generates the output test signature with the help of additional circuitry. The self-generated test signature from the DUT is analyzed by using onchip resources for testing the LNA and controlling its calibration knobs to compensate for multi-parameter variations in the LNA manufacturing process. Thus, the proposed methodology enables self-test and self-calibration of RF circuits without the need for external test stimulus. The proposed methodology is demonstrated through simulations as well as measurements performed on a RF LNA.

Iterative built-in testing and tuning of mixed-signal/RF systems

Design and test of high-speed mixed-signal/RF circuits and systems is undergoing a transformation due to the effects of process variations stemming from the use of scaled CMOS technologies that result in significant yield loss. To this effect, postmanufacture tuning for yield recovery is now a necessity for many high-speed electronic circuits and systems and is typically driven by iterative test-and-tune procedures. Such procedures create new challenges for manufacturing test and built-in self-test of advanced mixed-signal/RF systems. In this paper, key test challenges are discussed and promising solutions are presented in the hope that it will be possible to design, manufacture and test “truly self-healing” systems in the near future.

Self-Calibrating Embedded RF Down-Conversion Mixers

This paper proposes a self-calibrating approach for embedded RF down-conversion mixers. In the proposed approach, the output of the RF mixer is analyzed by using on-chip resources for testing and the mixer performs self-compensation for parametric defects using tuning knobs. The tuning knobs enable the RF mixer to self-calibrate for multi-parameter variations induced due to process variability. Using this methodology, it is demonstrated that performance compensation of RF down-conversion mixers can be performed simultaneously for critical specifications such as Gain and 1-dB compression point (P1dB).

A low cost method for testing integrated RF substrates

In this paper, a novel low-cost method for testing embedded passive filters in integrated radio frequency (RF) substrates is introduced. The introduced test method does not require external test stimulus and enables testing of these embedded RF passive circuits without vector network analyzer (VNA). The core principle of the proposed test method relies on including the passive filter through substrate surface probes into the feedback network of an external amplifier circuit located on the probe card, thereby causing the amplifier to oscillate. Failures in an embedded RF filter are detected by measuring changes in the oscillation frequency of the amplifier circuit. Hence, the test setup cost reduces. The introduced test method is demonstrated with both simulations and measurements. In addition, wafer-level testing of embedded RF passive circuits is also illustrated.

A Novel Method for Testing Integrated RF Substrates

This paper discusses a novel and a low cost testing technique for integrated radio frequency (RF) substrates with embedded passive filters. This technique is based on resonator and regression analyses and uses low-frequency measurements to predict the filters insertion loss at high frequency. Moreover, only one-port (Sll) measurement is required for this two-port parameter prediction. Hence; this novel testing technique reduces the cost of test equipments and testing time. To show the feasibility of this proposed methodology both simulation and hardware results are presented for embedded diplexer. The results show that by our proposed methodology, testing frequency can be reduced by approximately 47% for low-pass filter and 33% for high-pass filter of the design frequency.

A low-cost test approach for embedded RF passive circuits

A new low-cost test approach is proposed for testing embedded RF passive filters (ERPFs) by one-port measurement. By this method, ERPFs testing is possible without a vector network analyzer. This method also enables testing of ERPFs without external test stimulus. In the proposed test approach, a shift in the oscillation frequency of the test-setup is used to detect faults in the filters, but this test approach does not require reconfiguration or conversion of filters into an oscillator as it is done in conventional oscillation-based methods. The core principle of the method is to include an ERPF through a one-port substrate surface probe into an external RF oscillator circuitry, located on the probe card. Such one-port probing causes a change in the oscillation frequency of the oscillator because of the loading from the RF filter, thus enabling low-cost testing of RF filters.

Low cost system-in-package module using next generation low loss organic material

Miniaturization of wireless sub-systems through high-density integration of actives and passives is in hour of need with the increasing demand for portable devices. Considering that a thin, planar form-factor is much sought-after for mobile devices, it is essential to shrink packages in terms of thickness. This paper presents, for the first time, super-thin, three-metal-layer WLAN LNA and receiver modules with chip-last embedding pioneered by Georgia Tech Packaging Research Center (GT-PRC). The modules composed of a thin organic core and an organic build up layer measure 130 um in thickness, which is smaller by a factor of nearly 10× compared to the conventional wire-bonding or flip-chip packages. Such miniaturization was primarily achieved by shrinking of embedded passives with the use of next generation material X-L (high Dk) with high dielectric constant. The modules were fabricated using conventional low cost process with the addition of cavity fabrication through laser ablation, followed by embedding of 100 um-thick GaAs dies. The receiver module was measured to have a gain of 9.2 dB at 2.4 GHz, and out-of-band rejection of nearly 30 dB at 2 GHz and 5 GHz.

RF substrates yield improvement using package-chip co-design and on-chip calibration

In this paper, yield improvement methodology is proposed for RF substrates with embedded RF passive circuitry. The proposed methodology introduces a concept of package-chip co-design and on-chip calibration of active circuitry for the yield improvement of off-chip passive embedded RF filters. RF receiver architecture for the package-chip co-design and on-chip calibration technique is presented. Using the proposed methodology, it is shown that the yield of RF substrates is improved from 88% to 98%. Also, the measurements results are presented.

Low-Cost Specification Based Testing of RF Amplifier Circuits using Oscillation Principles

In this paper, we propose a low-cost approach for testing GHz RF amplifiers. It is demonstrated for the first time that GHz RF amplifiers can be tested for their specifications using oscillation principles. In the test mode, the RF test signal is “self generated” by the amplifier with the help of additional external circuitry which forces the amplifier to oscillate (Barkhausen criterion) around its characteristic frequency. The RF sinusoidal output from the oscillating RF amplifier is down-converted to a lower frequency enabling low frequency test response analysis as well as increased sensitivity to parametric deviations. In addition to the detection of catastrophic failures, it is shown that multiple RF specifications (Gain, P1dB, and Noise Figure) can be predicted via analysis of the frequency of the down-converted response. To account for RF parasitics on the production floor, a calibration technique is proposed in the test-setup. Thus, the proposed method reduces test cost significantly by reducing the cost of test setup (by as much as 80%) and significantly reducing test time. The viability of the proposed test method is demonstrated both by simulation experiments and measurement.