Integrated cancellation circuit for RF converter spurious tones
AssigneeBAE Systems Information and Elecronic Systems Integration Inc.
InventorsThomas E. Collins, III, Douglas S. Jansen
Life of this patent
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Abstract
Techniques are disclosed for eliminating or otherwise sufficiently suppressing spurious signals. The techniques are particularly useful in applications such as those that employ aggressor frequency sources along with a frequency conversion or mixing function, and especially applications implemented as a system-on-chip. In the spur-training mode, a spur-canceller circuit identifies spurious tones associated with the host system to neutralize those tones when running in a normal mode. The tones are neutralized using a comb generator with variable phase and gain by way of cancellation with comb output signals having substantially the same amplitude and a phase that is 180° out of phase with the aggressor tone to be cancelled.
Claims20
A method for canceling spurious tones in an RF converter having a mixer and an output, the method comprising:
- in a spur-training mode wherein a spurious tone associated with an aggressor source is present, generating a set of phase coherent harmonics of the aggressor source using a comb generator with variable phase and gain;
- inserting the harmonics into a signal path prior to the mixer;
- adjusting gain and phase of the comb generator while monitoring the output of the RF converter until the spurious tone is reduced to an acceptable level;
- and
- after the spurious tone is reduced to an acceptable level, storing the corresponding gain and phase settings of the comb generator along with a corresponding aggressor source state identifier.
A system for canceling spurious tones in an RF converter having a mixer and an output, the system comprising:
- a comb generator with variable phase and gain for generating, in a spur-training mode wherein a spurious tone associated with an aggressor source is present, a set of phase coherent harmonics of the aggressor source;
- a summer module for inserting the harmonics into a signal path prior to the mixer;
- a digital controller for adjusting gain and phase of the comb generator while monitoring the output of the RF converter until the spurious tone is reduced to an acceptable level;
- and
- a memory for storing, after the spurious tone is reduced to an acceptable level, the corresponding gain and phase settings of the comb generator along with a corresponding aggressor source state identifier.
A system for canceling spurious tones in an RF converter having a mixer and an output, the system comprising:
- a comb generator with variable phase and gain for generating, in a spur-training mode wherein a spurious tone associated with an aggressor source is present, a set of phase coherent harmonics of the aggressor source;
- a summer module for inserting the harmonics into a signal path prior to the mixer;
- a digital controller for adjusting gain and phase of the comb generator while monitoring the output of the RF converter until the spurious tone is reduced to an acceptable level;
- and
- a memory for storing, after the spurious tone is reduced to an acceptable level, the corresponding gain and phase settings of the comb generator along with a corresponding aggressor source state identifier;
- wherein the system is included in a system-on-chip configuration, and the RF converter is a dual RF converter having first and second converter stages, and the aggressor source is a local oscillator associated with the first converter stage.
Dependencies are inferred from the claim text.