FBR DC vector offset removal using LO phase switching

1. A feedback receiver (FBR), comprising:

a FBR signal input configured to receive a radio frequency (RF) signal;

a first local oscillator (LO) signal input configured to receive a first LO signal having an LO frequency;

a second LO signal input configured to receive a second LO signal having the LO frequency, wherein the second LO signal is phase shifted by approximately 90° relative to the first LO signal; and

a divider comprising: a first LO output coupled to the first LO signal input, a second LO output coupled to the second LO signal input, and a phase control terminal;

wherein a phase control word is provided to the phase control terminal to induce a time-varying phase shift in the first and second LO signals while concurrently retaining a 90° phase shift between the first and second LO signals;

wherein the phase control terminal is configured to induce the time-varying phase shift to occur in the first LO signal or the second LO signal by shifting the first LO signal or the second LO signal by substantially 180° while concurrently retaining the 90° phase shift between the first LO signal and the second LO signal.

2. The FBR of claim 1 , further comprising:

a directional coupler to provide the RF signal to the FBR signal input, wherein the directional coupler is continuously coupled to the FBR signal input.

3. The FBR of claim 1 , further comprising:

a first frequency conversion device having an RF input coupled to the FBR signal input and having a first LO input coupled to the first LO signal input; and

a second frequency conversion device having an RF input coupled to the FBR signal input and having a second LO input coupled to the second LO signal input.

4. The FBR of claim 3 , further comprising:

a first high pass filter downstream of the first frequency conversion device; and

a second high pass filter downstream of the second frequency conversion device.

5. The FBR of claim 4 , wherein the first high pass filter comprises a low-pass filter and a subtraction element.

6. The FBR of claim 1 , wherein the divider comprises: a frequency doubler which is connected to the LO input, and a frequency divider coupled to the frequency doubler.

7. A communication arrangement, comprising:

a first signal input configured to receive a frequency modulation signal;

a second signal input configured to receive an amplitude modulation signal;

a phase-locked loop comprising an output and a correcting input which is coupled to the first signal input;

an amplifying device comprising a control connection coupled to the second signal input, a signal input connected to the output of the phase-locked loop, and an amplifier output to provide an RF signal;

a divider with time variant phase control, comprising:

a reference signal input coupled to the output of the phase-locked loop,

a control terminal to receive a control word, and

first and second local oscillator (LO) outputs to provide respective first and second LO signals that are modulated based on the control word; and

a feedback receiver (FBR) in the feedback path comprising an i-data path and a q-data path, wherein the i-data path is adapted to provide an i-data component based on the RF signal and the first LO signal and wherein the q-data path is adapted to provide a q-data component based on the RF signal and the second LO signal,

wherein the control word induces a time-varying phase shift in the first and second LO signals to occur by shifting the first LO signal or the second LO signal by substantially 180° while concurrently retaining a 90° phase shift between the first LO signal and the second LO signal.

8. The communication arrangement of claim 7 , wherein the control word causes the i-data and q-data components to be balanced substantially about zero.

9. The communication arrangement of claim 7 , wherein the control word induces a regularly repeating phase-shift of approximately 180° in the i-data and q-data components in time.

10. The communication arrangement of claim 7 , further comprising:

a directional coupler configured to couple out a portion of the RF signal delivered by the amplifying device and deliver the portion of the RF signal to i-data path and q-data path of the FBR.

11. The communication arrangement of claim 10 , wherein the directional coupler is continuously coupled to i-data path and q-data path of the FBR.

12. The communication arrangement of claim 10 , further comprising:

a first frequency conversion device having an RF input coupled to the directional coupler and having a first LO input to receive the first LO signal; and

a second frequency conversion device having an RF input coupled to the directional coupler and having a second LO input to receive the second LO signal.

13. The communication arrangement of claim 12 , further comprising:

a first high pass filter downstream of the first frequency conversion device; and

a second high pass filter downstream of the second frequency conversion device.

14. The communication arrangement of claim 13 , wherein the first high pass filter comprises a low-pass filter and a subtraction element.

15. The communication arrangement of claim 7 , wherein, in response to the control word, the control terminal is configured to induce the time-varying phase shift to occur in the first LO signal or the second LO signal at a regular interval as a function of a predetermined pattern.

16. The communication arrangement of claim 15 , wherein the predetermined pattern comprises the time-varying phase shift to alternate between the first LO signal and the second LO signal at various times while concurrently retaining the 90° phase shift between the first LO signal and the second LO signal.

17. The communication arrangement of claim 15 , wherein the predetermined pattern comprises the time-varying phase shift to occur at both the first LO signal and the second LO signal at various times while concurrently retaining the 90° phase shift between the first LO signal and the second LO signal.