Current-stacked DX switch with high rf isolation
First Claim
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1. Apparatus for selectively attenuating, based on a select signal, rf signals, comprising:
- a fixed voltage dc power supply;
an rf switch having an rf input port and an rf output port and having a high-impedance state and a low-impedance state for selectively attenuating an rf signal between the rf input port and the rf output port, wherein the switch'"'"'s impedance state is selected by the select signal; and
an rf circuit having active elements for operating on the rf signal that is selectively attenuated by the rf switch, wherein the rf switch is dc connected in series with the rf circuit such that dc current from the power supply that flows through the rf switch also flows through the rf circuit.
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Abstract
An rf receiver front end that includes a switchable attenuation circuit or DX switch and uses a power saving technique. The switchable attenuation circuit is dc connected in series with one or more rf circuits so that power drawn from a constant voltage power supply is reduced. The rf circuit may include an rf mixer, a low-noise amplifier, or both.
16 Citations
12 Claims
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1. Apparatus for selectively attenuating, based on a select signal, rf signals, comprising:
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a fixed voltage dc power supply; an rf switch having an rf input port and an rf output port and having a high-impedance state and a low-impedance state for selectively attenuating an rf signal between the rf input port and the rf output port, wherein the switch'"'"'s impedance state is selected by the select signal; and an rf circuit having active elements for operating on the rf signal that is selectively attenuated by the rf switch, wherein the rf switch is dc connected in series with the rf circuit such that dc current from the power supply that flows through the rf switch also flows through the rf circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. Apparatus for selectively attenuating rf signals between an rf input port and an rf output port, comprising:
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a first dc current path, between the rf input port and the rf output port, that includes a first PIN diode connected between the rf input port and the rf output port; a second dc current path, between the rf input port and an rf ground terminal, that includes a second PIN diode rf coupled between the rf input port and the rf ground terminal and dc coupled in parallel with a third PIN diode, the third PIN diode further being rf coupled between the rf output port and the rf ground terminal; a first switch, responsive to a control signal, for selecting the first dc current path when the control signal is in a first state; a second switch, responsive to the control signal, for selecting the second dc current path when the control signal is in a second state; wherein the control signal causes the first and second switches to select either the first dc current path or the second dc current path; and wherein the rf impedance between the input port and the output port is relatively low when the control signal selects the first dc current path and is relatively high when the control signal selects the second dc current path. - View Dependent Claims (9, 10, 11)
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12. Apparatus for selectively attenuating, based on a select signal, rf signals, comprising:
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means for supplying dc power at a predetermined voltage; rf switch means for selectively attenuating an rf signal between an rf input port and an rf output port, wherein the rf switch means has a high-impedance state and a low-impedance state, and the rf switch means impedance state is selected by the select signal; and an active rf circuit means for operating on the rf signal that is selectively attenuated by the rf switch means, wherein the rf switch means is dc connected in series with the rf circuit means such that dc current from the dc power means that flows through the rf switch means also flows through the rf circuit means.
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Specification