SN74AUP1G00: XTAL PIERCE GATE OSCILLATOR

Berke Tosun

Prodigy 10 points

Part Number: SN74AUP1G00
Other Parts Discussed in Thread: SN74AUC1GU04, SN74AUC1G00

Tool/software:

Hello Everyone,

I am struggling to simulate the classical design shown as below:

I am using Pspice for TI to have the best results but could not get the square wave output as expected.

I have used the Pspice's original crystal library,
I have tried to model the resonator myself,
I choped the crystal and tried to build astable multivibrator,
I tried the simulation by skipping the bias point.
I tried different switching voltages
I tried to model it by using cmos topologies
I tried it one stage without buffer

It seems to me that, nand gate stays "LOW output" and just pushes crystal voltage to the output,

There should be feedbacking of low signal to the input and then there must be a switching action which's frequency determined by the crystal.

Can you help me to accomplish to get a square wave?

Thanks in advance!

10 months ago

0 Berke Tosun 10 months ago

Prodigy 10 points

+++ last issue I mentioned. There is only crystal's output with an offset:

I can try the same simulation with an ideal frequency source but that is not what I want:

second harmonic looks high but it can be expected with those repeated overshoots I guess:

Second stage looks helping:

I want to get similar results with a resonance circuit or resonator itself, then I would calculate the input impedances which is important for my main design.Maybe there could be a better analog model that you can suggest me. Thanks!

0 Clemens Ladisch 10 months ago in reply to Berke Tosun

Guru 317090 points

A Pierce oscillator requires an analog amplifier. The SN74AUP1G00 has some hysteresis and is unlikely to work.

You should use an unbuffered inverter, e.g., SN74AUC1GU04.

A Pierce oscillator requires some noise to start up. A simulation is likely to start up in an unrealistic, stable state.

0 Berke Tosun 10 months ago in reply to Clemens Ladisch

Prodigy 10 points

I am trying what you are suggested but same issue continues:

+1 Clemens Ladisch 10 months ago in reply to Berke Tosun

Guru 317090 points

The SN74AUC1G00 and SN74AUC1GU04 have different electrical characteristics.

0 Berke Tosun 10 months ago in reply to Clemens Ladisch

Prodigy 10 points

I know, I think what left to do is build it physically and then test. Thank you for your assistance..

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SN74AUP1G00: XTAL PIERCE GATE OSCILLATOR