Wide band polar modulator
View Patent ↗Some aspects of the present disclosure provide for polar modulation techniques that utilize an 180° phase shift module disposed downstream of a VCO-DCO. In some embodiments, this configuration allows a polar modulator to use the VCO-DCO to achieve small phase shifts (e.g., less than or equal to) 90°, while carrying out 180° phase shifts in the 180° phase shift module downstream of the VCO-DCO.
1. A circuit, comprising:
a controller to provide one or more control signals indicative of a digital data stream to be transmitted;
a voltage-controlled or digitally-controlled oscillator (VCO-DCO) downstream of the controller and coupled to the controller via a phase modulation control path; and
a 180° phase shift module downstream of the VCO-DCO and coupled to the controller via a 180° phase shift control path, wherein the 180° phase shift module comprises:
a counter having a first input coupled to an output of the VCO-DCO, a second input coupled to the 180° phase shift control path, and an output;
a gating module having a first input coupled to the output of the VCO-DCO, a second input coupled to the output of the counter, and an output; and
a variable divider having an input coupled to the output of the gating module.
2. The circuit of claim 1 , wherein the counter comprises:
a plurality of flip-flops, wherein at least one of the plurality of flip-flops is triggered on a falling edge of a clock signal.
3. The circuit of claim 1 , wherein the counter is configured to count a predetermined number of pulses of an oscillation signal provided by the VCO-DCO and provide a control signal when the predetermined number of pulses has been counted.
4. The circuit of claim 1 , wherein the controller comprises:
a phase analyzer to receive first and second digital samples corresponding to first and second temporally adjacent symbols, respectively, and configured to selectively provide a 180° phase shift control signal to the 180° phase shift module based on a phase offset between the first and second temporally adjacent symbols.
5. The circuit of claim 4 , further comprising:
a radio frequency antenna coupled to the 180° phase shift module and configured to receive a phase modulated high frequency signal therefrom, wherein the phase modulated high frequency signal is based on an oscillation signal provided by the VCO-DCO and includes the first and second temporally adjacent symbols.
6. The circuit of claim 5 , wherein the 180° phase shift module comprises:
a counter configured to hold the phase modulated high frequency signal for a predetermined number of pulses of the oscillation signal to induce the phase offset for the second symbol, relative to the first symbol.
7. The circuit of claim 1 , wherein the controller is configured to provide a phase modulation control signal to the VCO-DCO via the phase modulation control path to selectively induce a phase shift between two consecutive symbols output from the 180° phase shift module.
8. The circuit of claim 7 , wherein the phase shift provided by the VCO-DCO has a magnitude of less than or equal to approximately 90°.
9. The circuit of claim 8 , wherein the controller is configured to provide a 180° phase shift control signal to the 180° phase shift module via the 180° phase shift control path in coordinated fashion with the phase modulation control signal delivered to the VCO-DCO via the phase modulation control path.
10. The circuit of claim 9 , where the 180° phase shift control signal and the phase modulation signal cooperatively provide a phase shift having a magnitude of greater than approximately 90° and less than approximately 270° between the two consecutive symbols.
11. The circuit of claim 1 , wherein the VCO-DCO is configured to provide an immediate and precise 180° phase shift between temporally adjacent symbols.
12. A method, comprising:
providing an oscillation signal using a voltage-controlled or digitally-controlled oscillator (VCO-DCO), the oscillation signal comprising pulses;
providing a phase modulated high frequency signal based on the oscillation signal, wherein the phase modulated high frequency signal includes a first symbol during a first symbol period;
detecting a desired phase offset for a second symbol to be transmitted in a second symbol period temporally adjacent to the first symbol period;
at the start of the second symbol period, delaying the phase modulated high frequency signal for a predetermined number of pulses of the oscillation signal to generate the second symbol with the desired phase offset relative to the first symbol.
13. The method of claim 12 , wherein the phase modulated high frequency signal has a frequency that is less than a frequency of the oscillation signal.
14. The method of claim 12 , wherein the phase offset is 180°.
15. A circuit, comprising:
a controller including a phase analyzer to determine a phase offset between first and second temporally adjacent symbols;
a voltage-controlled or digitally-controlled oscillator (VCO-DCO) downstream of the controller and coupled to the controller via a phase modulation control path, the VCO-DCO configured to provide a modulated oscillation signal made up of pulses; and
a 180° phase shift module downstream of the VCO-DCO and coupled to the controller via a 180° phase shift control path, the 180° phase shift module comprising a counter configured to selectively hold the phase modulated high frequency signal at a first state for a predetermined number of pulses of the modulated oscillation signal or not hold the phase modulated high frequency signal at the first state for the predetermined number of pulses based on the phase offset.