This is a Building Block for our Quantum Experimenters. It can be used to switch between two dc voltages or dc coupled af. The TTL level can be chosen between 3.3 V or 5.0 V. It was designed for our Lithium Team, but the use is very universal.

This is a switch built around an ADG413 from Analog Devices. This is an LC² MOS Precision Quad SPST Switch. We use two in parallel to make use of the whole ic as well as to lower the series resistance.

The ouput is buffered with an opamp (e.g. OP07) to achieve a low output impedance. A series resistor of 47 Ω increses it to somewhat near 50 Ω - which is not necessary for dc / af applications, but it protects the circuit in case of a shorted output.

All inputs and outputs span a range of ±10 V.

The necessary logic level can be defined by the assembly of the voltage regulator. Use either a 7805 or a 7833 in a TO-220 case to supply the switch ic. Our model used a 7805.

• Power Supply, e.g. Leomod
• Lemo Cable, e.g. this or that.

S1 + S4 : +8 V. S2 + S3 : 0 V

Switching Speed, Low to High, (S2, S3) to (S1, S4) approx. 50 µs



Switching Speed, High to Low, (S1, S4) to (S2, S3) approx. 50 µs

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