4016 switches

I built and tested one of the programmable amplifiers. They consist of an opamp and a 4016 switch. It works but I found out that the 4016 don't like to switch negative voltages. The datasheet was not clear about this. So I added an offset. This solves the problem. Later I need to get rid of this offset by using a highpass filter.

Looking through several datasheet I found out that the 4016 can only be used when input or output is in the range of -0.5 V .. VCC. So I need to keep the amplification low. An opamp with fixed amplification will amplify the signal to the needed level.

I use 2 inverting programmable amplifiers. In this setup the voltages over the switches can be negative. To solve this I will use an inverter behind each programming amplifier. The TL-082 are dual opamps so I van use one of them as inverter. No extra chips are needed as I already planned to use 2 IC's.

So no fundamental changes are needed in my design. I just have change the gain distribution and add 2 inverters.