研究目的
To verify the silicon implementation of improved Nagata current mirrors that are insensitive to power supply voltage variations.
研究成果
The silicon verification confirmed that the improved Nagata current mirror circuits provide constant output current insensitive to power supply voltage variations over a wide range. Circuit types T2 and T3 showed the best performance with small variations. Although temperature sensitivity exists, the constant characteristics are maintained. The proposed circuits are simple, small, and suitable for use as stable current references in analog ICs. Future work will focus on developing temperature-insensitive versions.
研究不足
The circuits do not account for temperature variations, as they are not designed to be temperature-insensitive. Process variations caused measured output currents to be approximately 10% lower than simulated values. The constant output current characteristics deteriorated in circuit type T4 compared to others.
1：Experimental Design and Method Selection:
The experiment involved designing and fabricating improved MOS current mirror circuits based on the Nagata current mirror, using multiple current peaks to achieve insensitivity to power supply voltage variations. SPICE simulations were used for initial validation.
2：Sample Selection and Data Sources:
Prototype chips were fabricated using TSMC 0.35μm CMOS process. Each chip contained 4 sets (A, B, C, D sides) of 5 circuit types (T1 to T5), with 5 chips evaluated and 20 samples measured per circuit type.
3：35μm CMOS process. Each chip contained 4 sets (A, B, C, D sides) of 5 circuit types (T1 to T5), with 5 chips evaluated and 20 samples measured per circuit type.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Fabrication through TSMC 0.35μm CMOS process; measurement equipment included setups for varying input voltage (Vin) from 0 to 5.0V and output voltage (Vout) from 1V to 3V; a hair dryer was used for temperature evaluation.
4：35μm CMOS process; measurement equipment included setups for varying input voltage (Vin) from 0 to 0V and output voltage (Vout) from 1V to 3V; a hair dryer was used for temperature evaluation.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Output current (Iout) was measured with respect to Vin and Vout. Temperature characteristics were evaluated by heating the chip with a hair dryer to ~40°C and comparing with room temperature (~20°C) measurements. Data were collected for all circuit types, sides, and chips.
5：Data Analysis Methods:
Standard deviation and variation percentages were calculated to assess output current stability. Measured results were compared with SPICE simulation results to evaluate discrepancies.
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