Transmitter Baseband Correction for RF Pulling Effect
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Solution Overview
Problem
In wireless communication systems, the 'pulling effect' caused by radio frequency signals coupling back to the oscillator in smaller transmitters introduces phase errors, leading to reduced performance, and existing calibration mechanisms either increase cost and complexity or introduce unwanted phase noise.
Innovation Solution
A correction matrix is applied to the analog signal before mixing to eliminate the phase error, using a pre-processing method that generates a correction signal to cancel out the phase error, thereby eliminating the pulling effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a calibration mechanism is arranged subsequent to a mixer to eliminate the pulling effect, then the pulling effect can be eliminated, but the required bandwidth becomes too high, increasing cost and complexity
Solution Approach 1:
The patent applies a correction matrix to the baseband signal before the signal enters the mixer. This preliminary correction modifies the baseband signal in advance to compensate for the pulling effect that will occur during frequency multiplication, thereby eliminating the need for high-bandwidth calibration mechanisms after the mixer.
2Reliability
If a calibration circuit is arranged in a phase locked loop to eliminate the pulling effect, then the pulling effect can be eliminated, but unwanted phase noise is introduced, reducing transmitter performance
Solution Approach 1:
The patent extracts the pulling effect compensation function from the phase locked loop and implements it separately through a correction matrix applied to the baseband signal. This separation allows the pulling effect to be eliminated without introducing the phase noise that would result from modifying the phase locked loop.
3Volume of moving object
If the transmitter size is reduced to meet miniaturization requirements, then compactness is improved, but radio frequency signals couple back to the oscillator, introducing phase errors
Solution Approach 1:
The patent applies a correction matrix to the baseband signal before frequency multiplication to pre-compensate for the phase errors that will be introduced by the pulling effect in miniaturized transmitters. This preliminary anti-action counteracts the harmful coupling effect without requiring physical separation between components.
Data Source
AI summary
A transmitter with compensating mechanism of pulling effect includes a correction unit and an output unit. The correction unit includes a memory circuit and a first address generation circuit. The memory circuit is configured to store a look up table, wherein the look up table stores correction data corresponding to an in-phase data signal, a quadrature data signal, and at least one system parameter. The first address generation circuit is configured to generate a first address according to the in-phase data signal, the quadrature data signal, and the at least one system parameter, in order to output a correction signal via the correction data. The output unit is configured to modulate the correction signal according to an oscillating signal to generate a modulated signal, and amplify the modulated signal to generate an output signal.