Apparatus and methods for biasing radio frequency switches
First Claim
1. A radio frequency (RF) switching circuit comprising:
- a field effect transistor (FET) switch electrically connected along a signal path; and
an adaptive biasing circuit configured to generate a bias voltage, wherein a gate of the FET switch is biased in part by the bias voltage, the adaptive biasing circuit comprising;
a low pass filter configured to generate a low pass filtered voltage based on low pass filtering a signal path voltage of a node of the signal path;
a buffer circuit configured to receive the low pass filtered voltage and to generate a buffered voltage; and
a voltage shifting circuit configured to generate the bias voltage by shifting the buffered voltage by an amount of voltage that changes based on a state of a switch control signal.
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Accused Products
Abstract
Apparatus and methods for biasing radio frequency (RF) switches are provided herein. In certain configurations, an RF switching circuit includes a field effect transistor (FET) switch electrically connected between a first terminal and a second terminal, and an adaptive biasing circuit that generates a bias voltage used in part to bias a gate of the FET switch. The adaptive biasing circuit includes a low pass filter that generates a low pass filtered voltage based on low pass filtering a voltage of the first terminal, a buffer circuit that receives the low pass filtered voltage and generates a buffered voltage, and a voltage shifting circuit that generates the bias voltage by shifting the buffered voltage by an amount of voltage that depends on a state of a switch control signal.
43 Citations
20 Claims
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1. A radio frequency (RF) switching circuit comprising:
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a field effect transistor (FET) switch electrically connected along a signal path; and an adaptive biasing circuit configured to generate a bias voltage, wherein a gate of the FET switch is biased in part by the bias voltage, the adaptive biasing circuit comprising; a low pass filter configured to generate a low pass filtered voltage based on low pass filtering a signal path voltage of a node of the signal path; a buffer circuit configured to receive the low pass filtered voltage and to generate a buffered voltage; and a voltage shifting circuit configured to generate the bias voltage by shifting the buffered voltage by an amount of voltage that changes based on a state of a switch control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An electronically-implemented method of switch biasing, the method comprising:
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receiving a switch control signal and a voltage of a signal path as inputs to an adaptive biasing circuit; generating a low pass filtered voltage by low pass filtering the voltage of the signal path using the adaptive biasing circuit; generating a buffered voltage based on buffering the low pass filtered voltage using the adaptive biasing circuit; generating a bias voltage using the adaptive biasing circuit by shifting the buffered voltage by an amount of voltage that changes based on a state of the switch control signal; and controlling a gate voltage of a FET switch that is electrically connected along the signal path based in part on the bias voltage. - View Dependent Claims (13)
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14. A radio frequency (RF) system comprising:
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one or more series field effect transistor (FET) switches electrically connected along a signal path between a first terminal and a second terminal; and a first adaptive biasing circuit configured to generate a first bias voltage, wherein a first series FET switch of the one or more series FET switches is biased in part by the first bias voltage, wherein the first adaptive biasing circuit comprises; a low pass filter configured to generate a low pass filtered voltage based on low pass filtering a voltage of the first terminal; a buffer circuit configured to receive the low pass filtered voltage and to generate a buffered voltage; and a voltage shifting circuit configured to generate the first bias voltage based on the buffered voltage and a state of a switch control signal. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification