In the circuit for the 1 mA two-terminal current source, the leftmost PNP transistor (Q4) is a "bolt-on" to harvest the approximately 0 temperature-coefficient current in the left leg (a). The "glue" circuit allows the top current source to be m

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Other Materials from the Main Document

• Article «"Bolt-on" circuit, transistors create zero-drift current source»
• Figure 1. In the circuit for the 1 mA two-terminal current source, the leftmost PNP transistor (Q4) is a "bolt-on" to harvest the approximately 0 temperature-coefficient current in the left leg (a). The "glue" circuit allows the top current source to be m
• Figure 2. Current (and thus tempco) versus temperature for the basic two-terminal current sources are: at I = 250 µA, TC = -660 ppm/°C; at I = 500 µA, TC = -765 ppm/°C; at I = 1 mA, TC = -623 ppm/°C, at I = 2 mA, TC = -697 ppm/°C, and at
• Figure 3. This plot of output impedance Z_OUT (with independent current source I_SRC) for the designed current-source values shows both the steady-state performance over both input voltage and the minimum operating conditions
• Figure 4. The plot indicates ~0 tempco in the bolt-on MMT4403 (Q4) PNP transistor to the 1-mA I_SRC. The red plot line for the bolt-on shows a TC of -35 ppm/°C