High speed RF switch method employing differential current cancellation
| DWPI Title: Differential switching amplifier for use in radio frequency system, has first of pair of always off cascode transistors coupled between positive inverting input transistor and negative output terminal, and second of pair of transistors coupled between negative transistor and positive output terminal |
| Abstract: A radio frequency (RF) switch employing differential signal cancellation is disclosed. The differential RF switch enables high isolation and extremely small size by employing cascode current steering within a differential switching amplifier. Unlike series RF switches, isolation with the differential RF switch is limited by device mismatch, not switch parasitic capacitance, enabling high frequency operation. Since the differential RF switch can be placed within the already present cascode devices, there is no additional insertion loss from the switch. |
| Use: Differential switching amplifier for use in an RF system (claimed). |
| Advantage: The amplifier provides high isolation, minimal insertion losses, and low switching times all while occupying little space and consuming little power. The amplifier has no change in direct current (DC) bias voltage at a source or drain nodes of the cascode switch, thus saving significant area by removing the DC blocking capacitor required at the input side of the series switch. The radar system employs high transmit power and highly directional antennas to maintain a better signal-to-noise ratio (SNR) that are sensitive to leakage between transmit and receive paths through electromagnetic (EM) coupling inside the enclosed radar module and through power supplies. |
| Novelty: The amplifier (400) has a first of pair of always on cascode transistors adapted to couple half of a negative input current to a negative output terminal (IOUTminus ). A second of the pair of always on cascode transistors is adapted to couple half of a positive input current to a positive output terminal (IOUTplus) . A pair of bar enabled cascode transistors receives a bar enable gate signal (ENB), where the ENB is a logical opposite of enable gate signals (EN). A first of a pair of always off cascode transistors is coupled between a positive inverting input transistor (425) and the negative output terminal. A second of the pair of always off cascode transistors is coupled between a negative inverting input transistor (450) and the positive output terminal. A current source device is one of a transistor, an inductor, an LC tank circuit, or a resistor. |
| Filed: 4/12/2023 |
| Application Number: US18133584A |
| Tech ID: SD 15770.0 |
| 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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