LMC662

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SNOSC51C – APRIL 1998 – REVISED MARCH 2013

Figure 22. Guard Ring Connections: Follower

Figure 23. Guard Ring Connections: Howland Current Pump

The designer should be aware that when it is inappropriate to lay out a PC board for the sake of just a few

circuits, there is another technique which is even better than a guard ring on a PC board: Do not insert the

amplifier's input pin into the board at all, but bend it up in the air and use only air as an insulator. Air is an

excellent insulator. In this case you may have to forego some of the advantages of PC board construction, but

the advantages are sometimes well worth the effort of using point-to-point up-in-the-air wiring. See Figure 24.

(Input pins are lifted out of PC board and soldered directly to components. All other pins connected to PC board.)

Figure 24. Air Wiring

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