In-Circuit Leakage Tests

[lewisP]

What are some good troubleshooting techniques on how to test circuit leakages, stage leakages and component leakages. Leakage current upsets bias circuits and upsets the next following stage bias. Mostly from what I read is how to measure leakage current is to insert a current meter in series and measure the circuits or stage leakage. What are some signs to knowing if your circuit or stage has leakage. What are some approaches to take when dealing with components that has leakage current and is upsetting a circuit and how to track it down.

 

[D.A.(Tony)Stewart]

The most popular methods are to use a switched current source alternating from,sink to source at safe levels and looking at the response time for excessive capacitance which can signal an "almost short "in CMOS or a low voltage swing.

Backdriving junction points incircuit are often done by ATE but this won't detect leakage, just transfer function. Guard circuits are often used with outer coax, in low frequency current sources to null or reduce the effect of cable capacitance.