Can I adjust R4 and R5 to maintain a 12k input impedance?

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To maintain a 12k input impedance, adjustments to resistors R4 and R5 are necessary. The discussion highlights that the input and return currents must be equal, but some current may appear to flow to ground due to the resistor network configuration. It is clarified that no current actually leaves the system; instead, the grounded resistors are in parallel with the 12k resistor. Increasing R4 and R5 is essential to keep the overall impedance close to the required 12k. Understanding this configuration is crucial for effective circuit design.
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How do I reduce this resistor network.

The input current and the return current should be equal. But in this case, some current will also flow to ground. Can't get my head around this.
 

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likephysics said:
How do I reduce this resistor network.

The input current and the return current should be equal. But in this case, some current will also flow to ground. Can't get my head around this.

No current flows "to ground" per se. Just connect the two ends of the resistors that have ground symbols with a wire -- that's the only other path for current. No current "leaves" the system the way it's drawn.
 
So the two grounded resistors are in parallel with the 12k resistor?
 
likephysics said:
So the two grounded resistors are in parallel with the 12k resistor?

Yep!
 
The 12K is the input impedance of a receiver IC. I got to increase R4,R5 to keep the impedance close to 12k.
 
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