Precision thin film AC voltage divider
View Patent ↗A precision AC input voltage divider of input resistance R I and feedback resistance R F on a substrate is printed as a serpentine pattern for a thin line of resistive material. The input resistance is formed between a first and second terminal, and feedback resistance is formed between the second terminal and a third terminal. A first metallic conductor is formed on the substrate, connected to the first terminal, disposed to be adjacent to the input resistance, and having a distributed capacitive coupling to the input resistance that compensates for corresponding distributed stray capacitance from the input resistance to a circuit ground. A second metallic conductor is formed on the substrate, connected to the third terminal, disposed to be adjacent the feedback resistance, and having a distributed capacitive coupling to the feedback resistance that compensates for corresponding distributed stray capacitance from the feedback resistance to the circuit ground.
1. A resistive voltage divider comprising:
an insulating substrate;
a first terminal for application of an input voltage;
a second terminal;
a third terminal;
a first resistor formed on the insulating substrate and connected between the first and second terminals;
a second resistor formed on the insulating substrate and connected between the second and third terminals;
a first metallic conductor formed on the insulating substrate, connected at one end to the first terminal, disposed to be adjacent to at least part of the first resistor and having a distributed capacitive coupling to the first resistor that is selected to compensate for distributed stray capacitance from the first resistor to a circuit ground; and
a second metallic conductor formed on the insulating substrate, connected at one end to the third terminal, disposed to be adjacent to at least part of the second resistor and having a distributed capacitive coupling to the second resistor that is selected to compensate for distributed stray capacitance from the second resistor to the circuit ground.
2. A resistive voltage divider as in claim 1 wherein the insulating substrate is ceramic and the first and second resistors are serpentine patterns of nickel chromium.