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US 9,543,921 B2Granted
Apparatus and methods for controlling overshoot in digital step attenuators
AssigneeAnalog Devices Global
InventorFatih Kocer
Life of this patent
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Abstract
Apparatus and methods for controlling overshoot in digital step attenuators are disclosed. By configuring a multi-bit DSA such that an attenuation control block changes a plurality of control signals in a manner preventing a series cascade of attenuation units from having a transient attenuation value less than an initial and final value of attenuation, an overshoot condition can be prevented. Control signals transition the attenuation units to a first state of attenuation before they transition attenuation units to a second state of insertion.
Claims20
An attenuator component comprising:
- a plurality of attenuator units each having an attenuation value that define a range of attenuation values, wherein some of the attenuation values comprise higher attenuation values and some of the attenuation values comprise lower attenuation values, wherein the plurality of attenuator units are coupled together so as to receive an input and an output signal that has a final attenuation value, and wherein each of the plurality of attenuator units has a first state where a first attenuation value is applied to an input signal to produce a first output, and a second state where a second attenuation value is applied to an input signal to produce a second output, wherein the first attenuation value is greater than the second attenuation value;
- a control unit that in response to a logic signal selecting a final attenuation value, provides control signals to the plurality of attenuation units so that the plurality of attenuation units are placed into either the first state or the second state, wherein the control unit induces selected ones of the plurality of attenuation units having higher attenuation values to enter the second state after selected ones of the plurality of attenuation units having lower attenuation values enter the first state so as to reduce transient overshoot provided at the output during transition of the attenuator component from one attenuation level to another;
- and
- wherein the control signals comprise a first control signal and a first inverted control signal and the control unit comprises a delay circuit, the delay circuit having at least two inverter stages connected in a cascade, wherein the delay circuit is configured to receive the first control signal at an input of the cascade and to provide the first inverted control signal at an output of the cascade, wherein the first control signal and the first inverted control signal are provided to a select one of the plurality of attenuation units so as to cause the select one of the plurality of attenuation units to transition from the second state to the first state faster than the select one of the plurality of attenuation units transitions from the first state to the second state.
1 more element
A method comprising:
- operating a plurality of attenuator units each having an attenuation value that define a range of attenuation values, wherein some of the attenuation values comprise higher attenuation values and some of the attenuation values comprise lower attenuation values, wherein the plurality of attenuator units are coupled together so as to receive an input and an output signal that has a final attenuation value;
- providing an input signal to the plurality of attenuator units;
- operating the plurality of attenuator units in a first state where a first attenuation value is applied to an input signal to produce a first output, and a second state where a second attenuation value is applied to an input signal to produce a second output, wherein the first attenuation value is greater than the second attenuation value;
- receiving a logic signal selecting a final attenuation value;
- in response to the logic signal providing control signals to the plurality of attenuation units so that the plurality of attenuation units are placed into either the first state or the second state;
- controlling selected ones of the plurality of attenuation units having higher attenuation values to enter the second state after selected ones of the plurality of attenuation units having lower attenuation values enter the first state so as to reduce transient overshoot of an output signal during transition of the attenuator component from one attenuation level to another;
- and
- providing a first control signal and a first inverted control signal from a delay circuit having at least two inverters to a select one of the plurality of attenuation units so as to cause the select one of the plurality of attenuation units to transition from the second state to the first state faster than the select one of the plurality of attenuation units transitions from the first state to the second state.
5 more elements
Dependencies are inferred from the claim text.