Mixer Phase Shift via VGA Gain Control
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Solution Overview
Problem
Related-art phase shifters in communication systems experience significant signal transmission losses due to passive elements like resistors and capacitors, particularly in high-frequency bands, necessitating additional amplifiers that increase power consumption.
Innovation Solution
A mixer configuration that omits the IQ generator from the signal path, using VGAs to amplify signals with gains of cos θ and sin θ, and separate mixers for frequency conversion, followed by vector composition to achieve phase shift, thereby eliminating the need for additional amplifiers and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an IQ generator is provided on the signal path to generate I and Q signals for phase shifting, then the phase shift function is achieved, but transmission loss increases significantly in high-frequency bands
Solution Approach 1:
The patent extracts the IQ generator from the signal path, eliminating it as a separate component. Instead, the phase shifting function is achieved by directly controlling the gain of two VGAs (variable gain amplifiers) with cosθ and sinθ coefficients, removing the source of transmission loss while preserving the phase shift capability
Solution Approach 2:
The patent merges the phase shifting function with the existing VGA gain control mechanism. By combining the amplitude control function of VGAs with phase shift coefficients (cosθ, sinθ), the system achieves both amplitude and phase control through a single integrated approach, eliminating the need for separate IQ generation circuitry
2Power
If an amplifier is added to the subsequent stage of the phase shifter to compensate for signal loss, then signal power is restored, but power consumption increases
Solution Approach 1:
The patent applies preliminary action by pre-amplifying the signal through VGAs before it enters the phase shifting stage. The VGAs with cosθ and sinθ gain control provide both amplitude adjustment and phase shift in advance, preventing signal loss from occurring in the first place and eliminating the need for subsequent amplification to compensate for losses
3Device complexity
If passive elements like resistors and capacitors are used in the IQ generator, then the circuit structure is established, but transmission loss increases particularly in high-frequency bands
Solution Approach 1:
The patent substitutes the mechanical/passive element-based IQ generator with an electronic solution using VGAs controlled by digital gain coefficients. This replacement eliminates resistors and capacitors from the signal path, substituting them with active electronic components that have much lower transmission loss, particularly in high-frequency bands
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration suppresses signal transmission loss and power consumption while maintaining both frequency conversion and phase shift functions, enhancing the efficiency of communication systems.
Implementation Method 1
a first VGA configured to input an input signal in a first frequency band from an input terminal, and amplify the input signal at the gain of cos θ to output the amplified input signal as a first signal
Implementation Method 2
a second VGA configured to input the input signal from the input terminal, and amplify the input signal at the gain of sin θ to output the amplified input signal as a second signal
Implementation Method 3
a first mixer, which is connected to a subsequent stage of the first VGA, and is configured to input the first LO wave output from the IQ generator, and use the first LO wave so as to apply, to the first signal, frequency conversion to a second frequency band, to thereby generate a third signal in phase with the input signal
Implementation Method 4
a second mixer, which is connected to a subsequent stage of the second VGA, and is configured to input the second LO wave output from the IQ generator, and use the second LO wave so as to apply, to the second signal, frequency conversion to a second frequency band, to thereby generate a fourth signal having a phase difference of 90° with respect to the input signal
Implementation Method 5
a combiner, which is connected to a subsequent stage of the first mixer and the second mixer, and is configured to apply vector composition to the third signal and the fourth signal, to thereby generate and output a fifth signal shifted in phase by the phase shift amount of θ° with respect to the input signal
Implementation Method 6
an IQ generator configured to input an LO wave, and output a first LO wave in phase with the LO wave and a second LO wave having a phase difference of 90° with respect to the LO wave
Data Source
AI summary
A mixer includes: a VGA (12) configured to amplify one of divided two portions of an input signal at a gain of cos θ; a VGA (13) configured to amplify another one of the divided two portions of the input signal at a gain of sin θ; an IQ generator (15) configured to input an LO wave, and output an LO wave in phase with the input LO wave and an LO wave having a phase difference of 90° with respect to the input LO wave; a mixer (16) configured to input the signal output from the VGA (12) and the LO wave which is output from the IQ generator (15), to output an RF signal; a second mixer (17) configured to input the signal from the VGA (13) and the LO wave which is output from the IQ generator, to output an RF signal; and a combiner (18).