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4-quad multiplier.

Muffassir

 hi all,

Here is below my attached schematic of the 4-quad multiplier using translinear principle in subthreshold operation.

[url=http://images.elektroda.net/64_1323247176.jpg][img]images.elektroda.net/.../url]

The above two oval marked are the Iin1=3nA , Iin2=3nA ,Vdd=0.4V , Ibias in the left of fig is Ibias=3nA , Vbias (below the FGMOS transistors) has the value Vbias=0.4V . input capacitors in the FGMOS are 150fF each at the input terminals (gate) of the PMOS .All MOS are of the same size.

I am doing the DC analysis(parametric) of the above circuit. for Iin1=-3nA to 3nA. And Iin2=-3nA to 3nA with 1nA steps. I expect to get the waveform(ignore the values of Iin1 and 2 in this image) as below.

[url=http://images.elektroda.net/48_1323248092.jpg][img]images.elektroda.net/.../url]

But i am getting constant 3nA for all values of Iin3 .

[url=http://images.elektroda.net/98_1323248000.png][img]images.elektroda.net/.../url]

Please correct my circuit where its going wrong and suggest me the answer.

Thanks .

Parents

  • I just had a thought as to what you might be doing wrong (lots of guesswork here since you've given so little information). You appear to be plotting the current through a current source. If you are trying to measure the output current from your circuit, that's clearly wrong, because then all you'll see is a constant current as delivered by that source. Instead you probably should be plotting the current through a voltage source (e.g. a zero volt source) or through the terminal of a device (e.g. one of the pins of a resistor, such as the one you circled in the schematic). If you've added a current source to the output of the circuit, you're actually driving current into that output and measuring it would not make any sense.

    Regards,

    Andrew.

Reply

  • I just had a thought as to what you might be doing wrong (lots of guesswork here since you've given so little information). You appear to be plotting the current through a current source. If you are trying to measure the output current from your circuit, that's clearly wrong, because then all you'll see is a constant current as delivered by that source. Instead you probably should be plotting the current through a voltage source (e.g. a zero volt source) or through the terminal of a device (e.g. one of the pins of a resistor, such as the one you circled in the schematic). If you've added a current source to the output of the circuit, you're actually driving current into that output and measuring it would not make any sense.

    Regards,

    Andrew.

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