Microwave field effect switch
First Claim
1. A wide frequency band switch for selectively supplying a microwave signal to a load comprising:
- a first field effect device having a source drain path in series between a source of the signal and the load;
inductive transmission line means in series with the source drain path of the first field effect device between the signal source and the load, said inductive transmission line means including N taps, where N is an integer greater than 1;
N second field effect devices, the kth second field effect device having a shunt source drain path connected to tap k, where k is selectively every value of N; and
means for selectively biasing the source drain paths of said first and second field effect devices so (1) during a first time interval the source drain paths of the first device and the N second devices respectively have first and second impedance states, and (2) during a second time interval the source drain paths of said first device and the N second devices respectively have said second and first impedance states, the first impedance state being a low resistive impedance, the second impedance state being a high capacitive impedance having a magnitude approximately on the order of magnitude of the impedance of the inductive transmission line means for frequencies of the microwave signal, whereby during the first time interval the capacitive impedances of the N second field effect devices and the inductive transmission line means form a matched low pass filter having a cut off frequency in excess of the highest frequency in the band so that the signal from the source is coupled through the first field effect device via the matched low pass filter to a load, and during the second time interval the N second field effect devices shunt current of the source flowing in the inductive transmission line means away from the load.
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Accused Products
Abstract
A monolithic microwave integrated circuit switch includes a series field effect transistor having a source drain path in series with an inductive transmission line including plural taps. Source drain paths of plural shunt field effect transistors are connected to the taps. The source drain paths of the series and shunt transistors are biased so that the series and shunt source drain paths have complementary low and high impedance states. The high impedance state is capacitive, having a value on the order of magnitude of the inductive transmission line. During a first time interval, the capacitive and inductive impedances form a matched low pass filter to supply current from a microwave source to a load. During a second time interval, current from the microwave source flows through the shunt field effect transistors to be decoupled from the load. The circuit is in stripline form, with source electrodes of field effect transistors including first and second arms respectively having first and second elongated parallel sides. First and second elongated edges of drain electrodes of the transistors extend parallel to the elongated sides. A gate electrode of each transistor includes first and second elongated fingers respectively extending parallel the elongated sides and edges. The first finger is between the first side and first edge; the second finger is between the second side and second edge.
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Citations
18 Claims
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1. A wide frequency band switch for selectively supplying a microwave signal to a load comprising:
a first field effect device having a source drain path in series between a source of the signal and the load;
inductive transmission line means in series with the source drain path of the first field effect device between the signal source and the load, said inductive transmission line means including N taps, where N is an integer greater than 1;
N second field effect devices, the kth second field effect device having a shunt source drain path connected to tap k, where k is selectively every value of N; and
means for selectively biasing the source drain paths of said first and second field effect devices so (1) during a first time interval the source drain paths of the first device and the N second devices respectively have first and second impedance states, and (2) during a second time interval the source drain paths of said first device and the N second devices respectively have said second and first impedance states, the first impedance state being a low resistive impedance, the second impedance state being a high capacitive impedance having a magnitude approximately on the order of magnitude of the impedance of the inductive transmission line means for frequencies of the microwave signal, whereby during the first time interval the capacitive impedances of the N second field effect devices and the inductive transmission line means form a matched low pass filter having a cut off frequency in excess of the highest frequency in the band so that the signal from the source is coupled through the first field effect device via the matched low pass filter to a load, and during the second time interval the N second field effect devices shunt current of the source flowing in the inductive transmission line means away from the load.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
Specification