You should look at that circuit more closely. I don't think it will do what you intended. For one thing, you have the output tied to the power input. All your input will do is vary the load on the power supply.
You could do this with a relay, analog switch, or fets. What are you design constraints (cost, loading, board space, signal levels, etc) Why are you replacing the analog switch?
the thing is, analog switch occupies more space and i want to replace it with an alternate component which gives same performance with reduced cost. the specs are: it must work for a supply of 0-25V.
A arbitrary analog switch will take more space than a pre-packaged one. You can get away with less if you don't need certain specs that the more general purpose pre-packaged analog switch has to meet.
What specs don't you need? Is the input voltage always within some range or polarity so that a single P FET or N FET would work? Note that you have to consider how the gate will be driven too. How much current must pass from input to output? How high can the output impedance be? How low is the source signal impedance. How slow can it be? How high does the off impedance need to be? Now much input to output offset voltage can you tolerate?
For example, a simple analog switch can be made with two diodes and a resistor if the specs are suitable.
the analog switch i'm using is DG470, it works in the range of 4-7V i/p Supply. its cost is $0.60, so i want to replce it with an alternate one which must work for i/p of 3-3.5V and whose Vcc or Vdd should be in the range of 0-26V. pls guide in this issue.....
OK, but what about the answer to my other questions? You can't get a good answer without good specs.
What do you mean by the "i/p" being from 3 to 3.5V? Is that the complete range the input analog signal will have? Would the simple two-diode switch work, for example?
The discussion addresses the feasibility of replacing an analog switch with two N-channel MOSFETs controlled by an enable signal. Initial feedback highlights circuit design issues, such as the output being tied directly to the power input, which would only vary the load on the supply rather than switch the signal. Suggestions include adding a resistor or other components between Vdd and the output to properly control the signal path. The original poster clarifies the requirement: to pass the input signal to the output only when the enable signal is low. The motivation for replacement is to reduce board space and cost while maintaining performance. The existing analog switch, a DG470, operates with a 4-7V input supply and costs approximately $0.60. The desired replacement should function with an input signal range of 3-3.5V and a supply voltage (Vcc or Vdd) from 0 to 26V. Further considerations include signal voltage range, gate drive method, current capacity, output impedance, and acceptable offset voltage. Alternative solutions such as relays, discrete FETs, or simple diode-resistor switches are mentioned depending on the required specifications. Summary generated by the language model.
