Digital delay element for delay mismatch cancellation in wireless polar transmitters
First Claim
Patent Images
1. An RF transmitter, comprising:
- digital processor for producing outgoing digital IF signals comprising an envelope magnitude component and a phase component wherein the envelope magnitude component is produced on an envelope signal path and wherein the phase component is produced on a phase signal path, wherein the digital processor further includes a time shift block in at least one of the envelope and phase signal paths, wherein the time shift block implements a cubic polynomial that generates a time shift based upon a plurality of sequential sampled values of the outgoing digital IF signals to one of the envelope magnitude and phase components, the time shift block including;
a derivative estimation block for producing derivative estimates of a data sequence based upon the plurality of sequential sampled values of the outgoing digital IF signals; and
a clamped cubic spline (CCS) coefficient calculation block for producing coefficient values of the cubic polynomial based on the derivative estimates and a buffered sequence of samples;
first and second digital to analog converters (DACs) on the envelope and phase signal paths coupled to receive the envelope magnitude and phase components, respectively, the first and second DACs producing outgoing analog envelope and phase components;
first and second low pass filters for producing filtered outgoing magnitude and phase components, respectively, based upon the outgoing magnitude and phase components;
translational loop for up-converting the filtered outgoing phase component from IF to RF to produce an outgoing RF phase component; and
power amplifier that produces outgoing RF based upon the outgoing RF phase component having an outgoing power level based upon the filtered outgoing magnitude component.
4 Assignments
0 Petitions
Accused Products
Abstract
A circuit and method therefor provides programmable digital delay that is produced to introduces a delay in either an envelope or a phase signal path of an RF polar transmitter in order to eliminate the delay mismatch between the two paths. For two signal paths, a faster signal may be delayed by a digital processor or a slower signal may be transmitted early so that signals in the two signal paths arrive at a specified circuit node in synchronization. Timing shift may be implemented in either the envelope signal path or the phase signal path and may be used to reduce or increase the timing of a signal path.
-
Citations
17 Claims
-
1. An RF transmitter, comprising:
-
digital processor for producing outgoing digital IF signals comprising an envelope magnitude component and a phase component wherein the envelope magnitude component is produced on an envelope signal path and wherein the phase component is produced on a phase signal path, wherein the digital processor further includes a time shift block in at least one of the envelope and phase signal paths, wherein the time shift block implements a cubic polynomial that generates a time shift based upon a plurality of sequential sampled values of the outgoing digital IF signals to one of the envelope magnitude and phase components, the time shift block including; a derivative estimation block for producing derivative estimates of a data sequence based upon the plurality of sequential sampled values of the outgoing digital IF signals; and a clamped cubic spline (CCS) coefficient calculation block for producing coefficient values of the cubic polynomial based on the derivative estimates and a buffered sequence of samples; first and second digital to analog converters (DACs) on the envelope and phase signal paths coupled to receive the envelope magnitude and phase components, respectively, the first and second DACs producing outgoing analog envelope and phase components; first and second low pass filters for producing filtered outgoing magnitude and phase components, respectively, based upon the outgoing magnitude and phase components; translational loop for up-converting the filtered outgoing phase component from IF to RF to produce an outgoing RF phase component; and power amplifier that produces outgoing RF based upon the outgoing RF phase component having an outgoing power level based upon the filtered outgoing magnitude component. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A digital processor for producing outgoing digital IF signals comprising an envelope magnitude component and a phase component wherein the envelope magnitude component is produced on an envelope signal path and wherein the phase component is produced on a phase signal path, comprising:
a time shift block in at least one of the envelope and phase signal paths;
wherein the time shift block implements a cubic polynomial that generates a time shift based upon a plurality of sequential sampled values of the outgoing digital IF signals to one of the envelope magnitude and phase components, the time shift block including;a derivative estimation block for producing derivative estimates of a data sequence based upon the plurality of sequential sampled values of the outgoing digital IF signals; and a clamped cubic spline (CCS) coefficient calculation block for producing coefficient values of the cubic polynomial based on the derivative estimates and a buffered sequence of samples. - View Dependent Claims (7, 8, 9, 10)
-
11. A method of producing outgoing digital IF signals, comprising:
-
producing first and second path signals corresponding to the outgoing digital IF signals on first and second circuit paths, respectively; producing an indication of a unit time shift; receiving a first plurality of sequential sampled values of the first path signals and further receiving the indication of the unit time shift and a sample rate clock; and producing a second plurality of sequential sampled values at each sample clock of the sample rate clock, wherein the first plurality is larger than the second plurality; wherein the first path signals have modified signal values that are determined by solving a cubic polynomial based upon the first plurality of sequential sampled values of the first path signals. - View Dependent Claims (12, 13, 14, 15, 16, 17)
-
Specification