FSK Reader Circuit Using Divide-by-2 LO for Better Isolation
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Solution Overview
Problem
Conventional frequency shift-keying reader circuits face high power consumption and increased bit error rates due to high operational frequencies and low isolation between the local oscillation port and radio frequency signal, failing to meet the requirements of short distance wireless communication for low power consumption and high sensitivity.
Innovation Solution
A frequency shift-keying reader circuit design that includes a band-pass filter, low noise amplifier, injection-lock divide-by-2 frequency divider, sub-harmonic mixer, and low-pass filter, where the lock frequency is set to half the operational frequency, reducing power consumption and utilizing a sub-harmonic mixer for high signal isolation to minimize DC displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the operational frequency is increased to Giga Hertz level, then the demodulating quality is improved, but the power consumption increases
Solution Approach 1:
The patent changes the frequency parameter by using a divide-by-2 frequency divider to generate a local oscillation signal at half the radio frequency. This parameter change allows the system to maintain high demodulating quality while reducing power consumption by operating at a lower frequency for the local oscillation component.
Solution Approach 2:
The patent introduces a divide-by-2 frequency divider as an intermediary component between the radio frequency signal and the local oscillation signal. This intermediary generates a sub-harmonic local oscillation signal that enables effective demodulation without requiring the entire system to operate at the full radio frequency, thus reducing power consumption.
2Device complexity
If the isolation between local oscillation port and radio frequency signal is low, then the circuit complexity is reduced, but the bit error rate increases due to DC displacement
Solution Approach 1:
The sub-harmonic mixer acts as an intermediary that provides high isolation between the local oscillation port and radio frequency signal. By using the divide-by-2 frequency divider to generate a sub-harmonic local oscillation signal, the mixer achieves excellent rejection of the radio frequency signal at the local oscillation port, preventing DC displacement and reducing bit error rate without significantly increasing circuit complexity.
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
The design achieves reduced power consumption and improved sensitivity, meeting the specifications for short distance wireless communication by lowering power consumption and bit error rates through effective signal isolation.
Implementation Method 1
the injection-lock divide-by-2 frequency divider is locked at a lock frequency by the injection signal
Implementation Method 2
the sub-harmonic mixer receives the first differential signal, the second differential signal, the first oscillation signal and the second oscillation signal for performing a mixing procedure
Data Source
AI summary
A frequency shift-keying reader circuit includes a band-pass filter, a low noise amplifier, a first balun, an injection-lock divide-by-2 frequency divider, a sub-harmonic mixer and a low-pass filter. The band-pass filter performs a filtering procedure to a radio frequency signal, wherein the filtered radio-frequency signal is received by the low noise amplifier to provide an injection signal, and the injection signal is received by the first balun to generate a first differential signal and a second differential signal. The injection signal is received by the injection-lock divide-by-2 frequency divider to provide a first oscillation signal and a second oscillation signal, wherein the first differential signal, the second differential signal, the first oscillation signal and the second oscillation signal are received by the sub-harmonic mixer for performing a mixing procedure and thereafter generating an output signal, the low-pass filter performs a filtering procedure to the output signal.