Shared Local Oscillator RF Transceiver for Lower Power and Area
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Solution Overview
Problem
Transmitters/receivers for high-frequency wireless communication face high power consumption and large circuit area due to the presence of local oscillators in both devices.
Innovation Solution
A transmitter/receiver design that utilizes a local oscillator to up-convert an input signal for transmission and then uses this local oscillation signal as the local oscillator for down-conversion in the receiver, eliminating the need for a separate local oscillator in the receiving unit, and includes specific signal processing units like adding, multiplication, and subtraction units to generate and process transmission and reception signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If separate local oscillators are used in both transmitter and receiver, then signal processing capability is maintained, but power consumption increases and circuit area increases
Solution Approach 1:
The local oscillator in the frequency mixing unit performs dual functions: it generates the local oscillation signal for up-converting the input signal to generate the transmission signal, and simultaneously provides the same local oscillation signal to the down conversion mixer for down-converting the reception signal. This multi-functionality eliminates the need for a separate local oscillator in the receiving unit, thereby reducing power consumption and circuit area while maintaining signal processing capability.
2Speed
If high-frequency carrier wave is used for wireless communication, then communication frequency is increased, but power amplifier cannot amplify the carrier wave
Solution Approach 1:
The transmission signal is generated by up-converting the input signal to a high frequency through frequency mixing before transmission. By preparing the high-frequency carrier wave in advance through signal mixing rather than direct power amplifier amplification, the system enables high-frequency wireless communication without requiring the power amplifier to operate at frequencies beyond its capability.
Data Source
AI summary
A transmitter/receiver (1) up-converts, using an LO signal as a local oscillation signal, an IF signal having a predetermined frequency band, thereby generating a transmission signal RFTX. Moreover, the transmitter/receiver (1) generates a (LO+IF)2 signal and a (LO−IF)2 signal based on the IF signal and the LO signal. Using the LO signal obtained by adding-up of the (LO+IF)2 signal and the (LO−IF)2 signal, a reception signal RFRX is down-converted. Thus, a local oscillation signal generation unit of a receiving unit is not necessary.