Passive self-jammer cancellation in RFID systems
AssigneeImpinj, Inc.
InventorJohn D Hyde
Life of this patent
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Abstract
A self-jammer-cancellation circuit in an RFID system uses passive variable capacitance networks to attenuate phase-adjusted carrier signals, which are then combined with a received signal to reduce unwanted carrier signals in the received signal. The self-jammer-cancellation circuit also adjusts the passive variable capacitance networks such that the overall capacitance of each network remains constant or the overall relationship of capacitances between the networks remains constant.
Claims20
A self-jammer-cancellation (SJC) module configured to remove an unwanted carrier signal (UCS) from a signal-of-interest (SOI), the SJC module comprising:
- a multi-phase generator (MPG) configured to:
- receive a reference carrier signal;
- and
- provide a plurality of phase-adjusted reference carrier (PARC) signals;
- a plurality of variable-capacitance networks, each comprising an input, a first output, a first variable capacitance coupled from the input to the first output, and a second variable capacitance coupled to the input, each variable-capacitance network configured to:
- receive one of the plurality of PARC signals at the input,
- attenuate the PARC signal by adjusting the first variable capacitance,
- provide the attenuated PARC signal to the first output, and
- adjust the second variable capacitance such that a sum of the first and second capacitance values is substantially constant;
- and
- a signal combiner (SC) configured to:
- receive attenuated PARC signals from the variable-capacitance networks;
- receive a mixed signal comprising the SOI and the UCS;
- and
- combine the mixed signal with the attenuated PARC signals to provide an SJC output signal in which an amplitude ratio between the UCS and the SOI is substantially reduced relative to another amplitude ratio between the UCS and the SOI in the mixed signal.
The SJC module of claim further comprising a processor block configured to:
- determine a residual UCS component in the SJC output signal, and
- adjust the variable-capacitance networks to reduce the residual UCS component.
A method to remove an unwanted carrier signal (UCS) from a signal-of-interest (SOI) in a self-jammer-cancellation (SJC) module, the method comprising:
- receiving a plurality of phase-adjusted reference carrier (PARC) signals from a plurality of inputs, each of the PARC signals received from a respective input,
- adjusting a plurality of variable capacitance networks coupled to receive the PARC signals to attenuate at least one of the PARC signals such that each of the variable capacitance networks presents substantially the same impedance to the plurality of inputs;
- receiving a mixed signal comprising the SOI and the UCS;
- and
- combining the at least one attenuated PARC signal with the mixed signal to provide an SJC output signal in which an amplitude ratio of the UCS to the 501 is substantially reduced relative to another amplitude ratio of the UCS to the SOI in the mixed signal.
A self-jammer-cancellation (SJC) module configured to remove an unwanted carrier signal (UCS) from a signal-of-interest (SOI), the SJC module comprising:
- a multi-phase generator (MPG) configured to:
- receive a reference carrier signal;
- and
- provide a plurality of phase-adjusted reference carrier (PARC) signals;
- a plurality of variable-capacitance networks, each comprising an input, a first output, a first variable capacitance coupled from the input to the first output, and a second variable capacitance coupled to the input, each variable-capacitance network configured to:
- receive one of the plurality of PARC signals at the input,
- attenuate the PARC signal by adjusting the first variable capacitance,
- provide the attenuated PARC signal to the first output, and
- adjust the second variable capacitance such that the combined impedance of the variable-capacitance network seen by the MPG is substantially constant;
- and
- a signal combiner (SC) configured to:
- receive attenuated PARC signals from the variable-capacitance networks;
- receive a mixed signal comprising the SOI and the UCS;
- and
- combine the mixed signal with the attenuated PARC signals to provide an SJC output signal in which an amplitude ratio between the UCS and the SOI is substantially reduced relative to another amplitude ratio between the UCS and the SOI in the mixed signal.
Dependencies are inferred from the claim text.