Multifunctional RF limiting amplifier
| DWPI Title: Limiting amplifier, i.e RF limiting amplifier for use in dual channel sensor circuit for protecting over-driving of load sensitive to changes in operating temperature, has active load impedance circuit that includes active load feedback resistor electrically coupled between active load transistors |
| Abstract: Multifunctional RF limiting amplifiers having various configurations and functions are disclosed. In a first configuration, the RF limiting amplifier includes an active load output circuit that allows one to adjust the output impedance based upon the anticipated connected load impedance. In a second configuration, the RF limiting amplifier includes a pair of emitter-followers to buffer the output of a first stage, allowing the RF limiting amplifier to drive one or more second stages. A third configuration includes a pair of RF limiting amplifiers with their outputs mixed to implement a down conversion function. The third configuration may be used to drive dual SAW resonators for detecting the presence of biological or chemical agents. The RF limiting amplifier may be implemented in either bipolar junction transistors or CMOS transistors. |
| Use: Limiting amplifier, i.e two-stage limiting amplifier, multifunctional RF limiting amplifier, buffered Limiting amplifier and radio frequency (RF) limiting amplifier for use in a dual channel sensor circuit (claimed) protecting over-driving of the load sensitive to changes in operating temperature. Can also be used for dual-sensor applications and potential sensor applications to detect a specific biological or chemical agent exposed to a particular environment. |
| Advantage: The active current mirror configuration allows the active load feedback resistor to dominate the value of the output impedance by effectively increasing the transconductance of the pair of active load transistors by the voltage gain of the active current mirror. The first stage positive supply voltage network improves the current efficiency by allowing a wide range of adjustable alternating current (AC) gain and direct current (DC) amplitude at the nodes over a wide range of bias currents. The active load feedback resistor has the value of 100Ω, which can readily achieve the desired typical system impedance of 50Ω, thus achieving maximum coupling efficiency between the limiting amplifier 200 and a 50Ω load. The RF limiting amplifier has high efficient and provides wide adjustability of gain, output impedance, and output voltage limiting, and also protects the load from being over-driven. |
| Novelty: The limiting amplifier (200) has a first stage (210) including a pair of first stage transistors (212A,212B) adapted to receive an input voltage signal (205). A first stage positive supply voltage network is electrically coupled to the pair of first stage transistors. A first stage negative supply voltage network is electrically coupled to the pair of first stage transistors. The second stage (240) has a pair of second stage transistors (242A,242B) adapted to receive the corresponding pair of first stage output voltage signals. An active load output circuit (250) has a pair of active load transistors (252A,252B) electrically coupled to a corresponding the pair of second stage transistors. An active load impedance circuit includes an active load feedback resistor (254) electrically coupled between the pair of active load transistors. An active load ground resistor is electrically coupled to a first of the pair of active load transistors. |
| Filed: 11/19/2020 |
| Application Number: US16952745A |
| Tech ID: SD 14818.1 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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