Transceiver Loopback Switch for Carrier Leakage Calibration
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Solution Overview
Problem
Existing transceivers face challenges in stabilizing carrier leakage due to mismatches between mixers and local oscillators, leading to inefficiencies in signal transmission and reception.
Innovation Solution
A transceiver design incorporating a transmitter circuit, receiver circuit, and loopback switch that performs digital-to-analog conversion on calibration codes to adjust mixer biases, allowing for the reduction of carrier leakage by generating and controlling calibration signals, and a method to iteratively calibrate direct-current offsets in both paths to minimize leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transceiver uses a mixer and local oscillator for signal transmission, then signal conversion can be performed, but carrier leakage occurs due to mismatch between mixer and local oscillator
Solution Approach 1:
The patent applies preliminary action by performing calibration before normal signal transmission. A calibration mode is executed prior to operation to adjust mixer bias points and compensate for mismatches between the mixer and local oscillator, thereby reducing carrier leakage before actual signal processing begins
Solution Approach 2:
The patent implements feedback through a calibration process that measures carrier leakage and adjusts mixer bias accordingly. The system includes feedback mechanisms to detect leakage levels and automatically tune the mixer bias point to minimize the harmful effect, creating a closed-loop correction system
2Object-generated harmful factors
If the transceiver operates in calibration mode to reduce carrier leakage, then carrier leakage is reduced, but the normal signal transmission function is temporarily suspended
Solution Approach 1:
The patent applies periodic action by alternating between calibration mode and normal transmission mode in a time-division manner. The system periodically executes calibration routines at scheduled intervals rather than continuously, allowing normal signal transmission to proceed efficiently during operational periods while performing calibration maintenance at designated times
Solution Approach 2:
By performing calibration as a preliminary action before normal operation begins, the system prepares the mixer and local oscillator in advance to minimize carrier leakage during actual signal transmission, ensuring that the calibration overhead does not interrupt productive work
3Object-generated harmful factors
If the mixer bias is adjusted to control carrier leakage, then carrier leakage is reduced, but the complexity of the transceiver system increases
Solution Approach 1:
The patent applies self-service by implementing automatic calibration functionality within the transceiver itself. The system includes self-diagnostic and self-adjusting capabilities that automatically measure carrier leakage and tune mixer bias without requiring external intervention or complex manual calibration procedures, thereby reducing operational complexity
Solution Approach 2:
The patent utilizes parameter changes by adjusting the bias point parameter of the mixer to optimize its performance. By dynamically changing this key parameter during calibration and operation, the system can reduce carrier leakage without adding significant structural complexity, as the adjustment is made through control signals rather than physical modifications
Data Source
AI summary
A transceiver includes a transmitter circuit, a receiver circuit, and the loopback switch. The transmitter circuit performs a digital-to-analog conversion (DAC) operation on a calibration code without a transmission digital signal in a calibration mode to generate a calibration signal. The transmitter circuit up-converts the calibration signal and generates a transmission signal. The receiver circuit down-converts the transmission signal in the calibration mode and generates a receiving digital signal. The loopback switch electrically connects an output terminal of the transmitter circuit and an input terminal of the receiver circuit in the calibration mode. Thus, the transceiver may stably reduce a carrier leakage irrespective of processes, voltages, and temperatures.