Wave transmission lines and networks – Automatically controlled systems – Limiting of amplitude
Reexamination Certificate
1999-10-30
2003-01-07
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Automatically controlled systems
Limiting of amplitude
C333S262000, C200S181000
Reexamination Certificate
active
06504447
ABSTRACT:
TECHNICAL FIELD
The present invention discloses an effective technique to provide protection to high frequency circuits such as, but not limited to, low-noise amplifiers (LNA's) and millimeter wave integrated circuits (MMIC's) from electrostatic disturbance and potentially damaging high-power signals utilizing a microelectomechanical (MEM) device.
BACKGROUND OF THE INVENTION
In the construction of high-frequency integrated circuits, including MMIC's, power limiters are used at the input of circuits including low noise amplifiers to prevent device burnout from undesirably high levels of incident RF power. PIN diodes are typically used as power limiters, but these diodes are lossy, particularly at millimeter-wave frequencies. Further, diodes are difficult to use as they require impedance matching to the circuitry to which they are connected and tend to break down at very high power levels. Any loss due to a power limiter adds directly to the noise figure of the circuit, resulting in reduced sensitivity to desired signals and greater power requirements for the system resulting from additional complexities of design. Additionally, it is often difficult to monolithically integrate PIN diodes with transistors in a single process while the present invention may be integrated onto the same substrate as active devices such as transistors in a high-frequency integrated circuit process.
The present invention overcomes many of the difficulties found in the use of diodes as power limiters by providing a flexible mechanical bridge over a transmission line on the substrate which utilizes the electromagnetic field increase generated by temporary increases in power to short the harmful signal away from the remainder of the circuit.
Semiconductor devices are sensitive to excessive input voltages, such as those generated by ESD. High-speed devices are particularly sensitive. Circuits and systems that encounter ESD typically suffer from either immediate or latent component failure. In low frequency applications, the most common technique for protecting the input/output/power pins from damage is to include ESD diodes to shunt the undesired input signal away from the active devices and a series resistor to allow for sufficient time for the diodes to turn on. However, ESD diodes tend to have a large capacitance which prohibits their use in RF/microwave applications, and the series resistor is not acceptable in this type of system due to the incurred loss. The result of these shortcomings in diodes and resistors leave the typical high-speed devices, which operate at high frequencies, unprotected.
In contrast, the present invention sets forth a method to utilize a mechanical cantilever type switch to serve as protection from ESD.
SUMMARY OF THE INVENTION
In accordance with the present invention, a MEM implementation of a power limiter is presented, utilizing the electromagnetic field increase caused by a substantial increase in power through a transmission line on a substrate to cause the mechanical flex of a strip of conductive material traversing the transmission line. Upon flexion, the conductive material contacts the microstrip and provides a path by which the signal is shorted to ground. As a result, devices further down the circuit are protected from damage. The MEM power limiter is low loss and can easily be integrated with low noise active devices such as HEMT's or HBT's in MMIC's. The MEM limiter is intentionally designed to actuate at high RF inputs to protect the active devices from damagingly high signals. Although the speed of the MEM power limiters will typically be less than that of PIN diode limiters, by proper design of the limiter it is possible to protect the active devices from burnout.
Also presented in accordance with the present invention, is a MEM implementation of a cantilever type switch activated by an on-board signal from an active circuit such as a MMIC which may be used to as a safety mechanism to protect high speed devices from excessive input voltages or as a switch for other purposes such as an on/off switch. The advantage of the MEM cantilever type switch is that it is causes very low losses, thereby facilitating the protection of microwave devices in a manner that does not appreciably degrade their normal performance.
REFERENCES:
patent: 5619061 (1997-04-01), Goldsmith et al.
patent: 5638946 (1997-06-01), Zavracky
patent: 6020564 (2000-02-01), Wang et al.
patent: 6058229 (2000-05-01), Burrows et al.
patent: 6100477 (2000-08-01), Randall et al.
patent: 6133807 (2000-10-01), Akiyama et al.
patent: 6143997 (2000-11-01), Feng et al.
patent: 6188301 (2001-02-01), Kornrumpf et al.
patent: 6239685 (2001-05-01), Albrecht et al.
R. Holtzman, “Numerical Analysis Predicts PIN-Diode Limiter Performance”, Jun. 1995, Microwaves & RF, pp. 82-85.
P. Sahjani and E. Higham, “PIN Diode Limiters Handle High-Power Input Signals”, Apr. 1990, Microwaves & RF, pp. 195-199.
K. Bock, “ESD issues incompound semiconductor high-frequency devices and circuits”, 1998, Microelectronics Reliability 38, pp. 1781-1793.
C. Trantella et al., “An investigation of GaAs MMIC High Power Limiters for Circuit Protection”, 1997, IEEE MTT-S Digest, pp. 535-538.
David J. Seymour et al., “X-Band Monolithic GaAs PIN Diode Variable Attenuation Limiter”, 1990, IEEE MT-S Digest, pp. 841-844.
T. Parra et al., “X-Band Low Phase DIstortion MMIC Power Limiter”, May 1993, IEEE Transactions on Microwave Theory and Techniques, vol. 41, No. 5, pp. 876-879. 5/93.
G. Croft, J. Bernier, “ESD protection techniques for high frequency integrated circuits”, Jul. 9, 1998, Microelectronics Reliability 38, pp. 1681-1689.
Masahiro Hagio et al., “Monolithis Integration of Surge Protection Diodes into Low-Noise GaAs MESFETs”, May 1985, IEEE Transactions on Electron Devices, vol. ED-32, No. 5, pp. 892-895.
C. Goldsmith et al., “Characteristics of Micromachined Switches at Microwave Frequencies”, 1996, IEEE MTT-S Digest, pp. 1141-1144.
Mehran Megregany, “An Overview of Microelectromechanical Systems”, 1992, SPIE vol. 1793 Integrated Optics and Microstructures, pp. 2-11.
Hector J. Delos Santos et al., “Microwave and Mechanical Considerations in the Design of MEM Switches for Aerospace Applications”, 1997, IEEE, pp. 235-253.
Laney David
Larson Lawrence
Matloubian Mehran
HRL Laboratories LLC
Pascal Robert
Takaoka Dean
Tope-McKay & Associates
LandOfFree
Microelectromechanical RF and microwave frequency power... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Microelectromechanical RF and microwave frequency power..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Microelectromechanical RF and microwave frequency power... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3041321