Connecting Interface Clock Recovery Without a Crystal Oscillator
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Solution Overview
Problem
Existing connecting interface units for portable devices, such as digital cameras and MP3 players, require a stable clock signal for data transmission, which is typically generated by a crystal oscillator, but crystal oscillators are costly and frequency stability is affected by temperature changes, posing a challenge in designing units compliant with transmission standards without using a crystal oscillator.
Innovation Solution
A connecting interface unit that includes a frequency detector, phase detector, filters, an oscillator, and a transmitter circuit, which generates a clock signal based on input signals from a host system, eliminating the need for a crystal oscillator and maintaining compliance with transmission standards by adjusting frequency and phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crystal oscillator is used to generate a stable clock signal, then the frequency stability is improved, but the cost increases
Solution Approach 1:
The patent replaces the expensive crystal oscillator with a cost-effective RC oscillator circuit that uses resistors, capacitors, and logic gates to generate the clock signal. This substitution achieves acceptable frequency stability at a lower cost, directly addressing the contradiction between reliability and manufacturing cost.
Solution Approach 2:
The patent employs temperature compensation techniques that dynamically adjust the oscillator parameters (resistance and capacitance values) based on temperature conditions. This allows the system to maintain frequency stability across varying temperatures without using a crystal oscillator, resolving the contradiction between cost and reliability.
2Reliability
If a crystal oscillator is used to generate a stable clock signal, then the frequency stability is improved, but the device complexity increases
Solution Approach 1:
The patent substitutes the crystal oscillator with a simpler RC oscillator circuit composed of basic electronic components (resistors, capacitors, and logic gates). This replacement reduces device complexity while maintaining functional equivalence in generating a stable clock signal.
Solution Approach 2:
The patent uses temperature-dependent parameter adjustments in the RC circuit to compensate for frequency drift. By dynamically changing resistance and capacitance values based on temperature, the system achieves frequency stability without the complexity of a crystal oscillator.
3Reliability
If a crystal oscillator is used to generate a clock signal, then the transmission standard compliance is improved, but the temperature sensitivity increases
Solution Approach 1:
The patent implements temperature compensation by dynamically adjusting the RC circuit parameters (resistance and capacitance) based on detected temperature conditions. This allows the oscillator to maintain frequency stability across temperature variations, ensuring transmission standard compliance without the temperature sensitivity issues of crystal oscillators.
Solution Approach 2:
The patent incorporates a temperature detection mechanism that provides feedback to the RC oscillator circuit. Based on the temperature feedback, the system adjusts the oscillator parameters to compensate for temperature-induced frequency drift, maintaining compliance with transmission standards across varying temperature conditions.
Data Source
AI summary
A connecting interface unit and a memory storage device without a crystal oscillator are provided and include a frequency detector, a phase detector, an oscillator, a sampling circuit and a transmitter circuit. The frequency detector and the phase detector respectively detect frequency difference and phase difference between an input signal from a host system and a reference signal to generate a frequency signal and a phase signal. The frequency signal and the phase signal that have passed through a filter are transmitted to the oscillator to generate the reference signal for generating a clock signal. The sampling circuit generates an input data signal according to the reference signal. The transmitter circuit modulates an output data signal according to the clock signal to generate and transmit an output signal to the host system. Accordingly, the connecting interface unit conforms to the specification of a transmission stand.