Digital Oscillator Layout for Noise Isolation
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Solution Overview
Problem
Digital temperature compensated oscillators (DTCXO) face noise issues due to digital signal processing, which adversely affect the characteristics of the oscillation signal, and there is a need for an efficient layout that minimizes the influence of this noise while considering the connection relationships between circuits.
Innovation Solution
A circuit device is designed with a specific layout where the oscillation circuit, processing unit, and D/A conversion unit are positioned to minimize noise interference, including the use of A/D and D/A conversion units, memory units, and buffer circuits to efficiently route digital signal wiring and reduce noise propagation, along with a reference voltage generating circuit based on the work function difference of transistors to reduce power consumption and improve signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital signal processing is used for temperature compensation, then temperature compensation accuracy is improved, but noise is generated that adversely influences oscillation signal characteristics
Solution Approach 1:
The patent divides the circuit into distinct functional blocks: a digital signal processing unit (processing unit) and an oscillation signal generation unit (oscillation circuit), physically separated on the substrate. This segmentation isolates the noise-generating digital processing from the sensitive oscillation circuit, allowing high-precision temperature compensation while minimizing noise interference with oscillation signal characteristics.
2Area of stationary object
If the processing unit and oscillation circuit are placed close together for compact layout, then device area is reduced, but noise propagation from digital processing to oscillation circuit increases
Solution Approach 1:
The patent arranges the processing unit and oscillation circuit in different spatial regions on the substrate, utilizing available layout space efficiently. By strategically positioning these units in separate areas rather than simply increasing linear distance, the design achieves noise isolation while maintaining compact overall device area.
3Object-generated harmful factors
If the oscillation circuit is isolated from the processing unit to reduce noise, then noise influence is reduced, but connection complexity and wiring length increase
Solution Approach 1:
The patent introduces a D/A conversion unit as an intermediary component between the processing unit and the oscillation circuit. This mediator converts digital frequency control data to analog signals, enabling clean signal transmission while maintaining the physical separation needed for noise isolation. The intermediary simplifies the connection architecture compared to direct digital-to-oscillation circuit coupling.
Data Source
AI summary
A circuit device includes an A/D conversion unit, a processing unit that performs a temperature compensation process of an oscillation frequency based on temperature detection data and outputs frequency control data of the oscillation frequency, a D/A conversion unit, and an oscillation circuit. The D/A conversion unit (area DAC) is disposed on a first direction DR1 side of the A/D conversion unit (area ADC). When a direction crossing the first direction DR1 is defined as a second direction DR2, the processing unit (area DSPL) is disposed on the second direction DR2 side of the A/D conversion unit and the D/A conversion unit. When a direction opposite to the second direction DR2 is defined as a third direction DR3, the oscillation circuit (area OSC) is disposed on the third direction DR3 side or the first direction DR1 side of the D/A conversion unit.