Variable attenuator
First Claim
1. A variable attenuator comprising:
- an attenuator circuit having a signal path; and
a control circuit coupled to provide control signals to the attenuator circuit based on data stored in a memory circuit to establish a selected attenuation for the signal path of the variable attenuator, wherein the attenuator circuit comprises at least two current sources coupled to receive the control signals from the control circuit to establish bias current in selected PIN diodes of the attenuator.
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0 Petitions
Accused Products
Abstract
A variable attenuator formed from a combination of PIN diodes is provided. The PIN diodes may be coupled in a “T,” “p” or other appropriate configuration. At radio frequencies (RF), a PIN diode acts as a variable resistor with a resistance value based on the bias current of the PIN diode. To control the attenuation level of the variable attenuator, the bias current of the PIN diodes are selectively adjusted. Digital values relating to selected bias currents, and thus selected attenuation levels, are stored in a memory. These digital values are provided as control signals that set the bias current levels for the PIN diodes. The bias current levels control the attenuation level of the variable attenuator.
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Citations
34 Claims
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1. A variable attenuator comprising:
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an attenuator circuit having a signal path; and
a control circuit coupled to provide control signals to the attenuator circuit based on data stored in a memory circuit to establish a selected attenuation for the signal path of the variable attenuator, wherein the attenuator circuit comprises at least two current sources coupled to receive the control signals from the control circuit to establish bias current in selected PIN diodes of the attenuator. - View Dependent Claims (2, 23, 24, 25, 26, 27, 28, 29)
a processor;
at least one digital to analog converter; and
a bus that interconnects the processor, the memory, and the digital to analog converter such that the processor selects digital control signals from the memory, the memory places the selected digital control signals on the bus, and the digital to analog converter converts the digital control signals to control signals for the attenuator circuit.
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27. The variable attenuator of claim 26, wherein the at least one digital to analog converter comprises two digital to analog converters.
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28. The variable attenuator of claim 1, and further including a fixed attenuator stage bypassably coupled in series with the attenuator circuit.
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29. The variable attenuator of claim 28, wherein the fixed attenuator stage provides an attenuation level that is substantially the same as the highest attenuation level of the attenuator circuit.
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3. A variable attenuator comprising:
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an attenuator circuit having a signal path;
a control circuit coupled to provide control signals to the attenuator circuit based on data stored in a memory circuit to establish a selected attenuation for the signal path of the variable attenuator; and
a fixed attenuator stage bypassably coupled in series with the attenuator circuit. - View Dependent Claims (4, 30, 31, 32, 33, 34)
a processor;
at least one digital to analog converter; and
a bus that interconnects the processor, the memory, and the digital to analog converter such that the processor selects digital control signals from the memory, the memory places the selected digital control signals on the bus, and the digital to analog converter converts the digital control signals to control signals for the attenuator circuit.
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34. The variable attenuator of claim 33, wherein the at least one digital to analog converter comprises two digital to analog converters.
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5. A variable attenuator, comprising:
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an adjustable attenuator stage including at least three PIN diodes coupled to provide attenuation in a signal path of the variable attenuator;
a fixed attenuator stage bypassedly coupled in series with the signal path of the adjustable attenuator stage; and
a control circuit coupled to provide control signals to the adjustable attenuator stage and the fixed attenuator stage so as to select an attenuation level for the variable attenuator. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
a processor;
at least one digital to analog converter; and
a bus that interconnects the processor, the memory, and the digital to analog converter such that the processor selects digital control signals from the memory, the memory places the selected digital control signals on the bus, and the digital to analog converter converts the digital control signals to control signals for the adjustable attenuator stage.
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11. The variable attenuator of claim 5, wherein the adjustable attenuator stage comprises at least two current sources coupled to receive the control signals from the control circuit to establish bias current in selected PIN diodes of the attenuator.
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12. The variable attenuator of claim 11, wherein the attenuator circuit further comprises an RF choke in series with each current source.
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13. A variable attenuator, comprising:
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a control circuit including;
a look-up table that stores digital control signals for associated attenuation levels, and at least one digital to analog converter for converting digital control signals from the look-up table to analog voltages; and
an attenuator circuit including;
at least three PIN diodes coupled to provide attenuation in a signal path, and at least two current sources that are coupled to provide first and second bias current levels to the PIN diodes based on the analog voltages from the control circuit to establish a selected attenuation level. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A method for establishing an attenuation level in a signal path of an electronic circuit, the method comprising:
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receiving a signal that indicates a selected attenuation level;
accessing digital control signals that correspond to the selected attenuation level;
converting the digital control signals to analog voltages;
driving at least two current sources with the analog voltages; and
providing the output of the at least two current sources to PIN diodes to establish the selected attenuation level in the signal path. - View Dependent Claims (20, 21, 22)
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Specification