Harmonic-Rejection Transmitter Circuit Without Phase Interpolators
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Solution Overview
Problem
Conventional RF transmitters are area-inefficient and suffer from voltage loss due to the use of resistive phase interpolators and transformers, which complicates the design of mobile RF transceivers and increases power consumption.
Innovation Solution
A communication circuit with a voltage-mode harmonic-rejection mixer (HRM) that eliminates area-inefficient phase interpolators and transformers by using multiple digital-to-analog converters (DACs) to generate phase-shifted baseband signals, allowing operation at a 25% duty cycle and reducing voltage loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If resistive phase interpolators are used to generate phase-shifted baseband signals, then the transmitter can achieve frequency translation, but the chip area increases and voltage loss occurs
Solution Approach 1:
The patent extracts and removes the resistive phase interpolator from the transmitter architecture. Instead of using a phase interpolator to generate phase-shifted baseband signals, the invention directly uses multiple DACs to produce the required phase-shifted signals, thereby eliminating the area-inefficient and voltage-loss-prone phase interpolator component.
Solution Approach 2:
The patent makes the DACs multi-functional by having them directly perform both digital-to-analog conversion and phase shifting functions. The first pair of DACs generates in-phase baseband signals while the second pair generates quadrature-phase baseband signals, combining multiple functions into a single component to reduce overall chip area.
2Ease of operation
If resistive phase interpolators are used to generate phase-shifted baseband signals, then the transmitter can achieve frequency translation, but voltage loss occurs
Solution Approach 1:
The patent extracts and removes the resistive phase interpolator from the transmitter architecture. Instead of using a phase interpolator to generate phase-shifted baseband signals, the invention directly uses multiple DACs to produce the required phase-shifted signals, thereby eliminating the area-inefficient and voltage-loss-prone phase interpolator component.
3Ease of operation
If transformers are used in the transmitter circuit, then frequency translation can be achieved, but the device complexity and power consumption increase
Solution Approach 1:
The patent extracts and removes the transformer from the transmitter architecture. The voltage-mode harmonic-rejection mixer directly generates the RF signal without requiring a transformer for impedance matching or signal combination, thereby reducing circuit complexity and power consumption while maintaining frequency translation capability.
Solution Approach 2:
The patent replaces the traditional transformer-based impedance matching and signal combination mechanism with a voltage-mode mixing approach. The harmonic-rejection mixer uses capacitive coupling and voltage summation instead of transformer-based magnetic coupling, substituting a simpler electronic mechanism for the more complex electromagnetic transformation.
Data Source
AI summary
A communication circuit may include a first pair of digital-to-analog converters (DACs) coupled to an input of a first mixer and configured to generate first baseband signals. The communication circuit may further include a second pair of DACs coupled to an input of a second mixer and configured to generate second baseband signals. The second baseband signals may be shifted in phase relative to the first baseband signals.