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Part Number: OPA356-Q1
Our customer are considering that this device can drive coaxial cable at the following input conditions.
- Vin_pp=1Vpp @Vdd=3.3V
- Vcm=+1.5V (+/-0.5V=1Vpp)
If it is not possible to use this device at the above condition for cable driver, please give us some other device that you recommend.
(We are considering OPA355 and OPA354 as well.)
In reply to Sean Cashin:
In reply to K.Hamamoto:
Thank you for your support.
For those devices what we found, do you think the slew rate is enough at the following condition?
- Fsig = 125MHz (Max) : Sin wave
- Vout_pp = 1.5Vpp (Max)
Because OPA355 and OPA356 has ability 300V/us of slew rate. However for the above condition, I think the slew rate should be more than 600V/us. What do you think?
Is my understanding correct? (dt/dV = PI * Fsig * Vp = PI * 125[MHz] * 1.5Vpp = 589V/us)
Yes, your understanding is correct. The OPA355 and 356 will be slew rate limited under this condition. The slew rate is what causes the amplifier's large signal bandwidth to be less than its small signal bandwidth. To determine whether or not an amplifier can drive a coaxial cable at a desired signal voltage, just check to see how well it can drive a load of Rsig+Zcharacteristic, or in this case 50+50=100ohms. This is limited by the amplifier's linear current output rating and the signal voltage.
In reply to hasmukh kabariya:
I understood. And I confirmed the behavior at the 50+50 ohm capability with TINA-TI.
It looks the output is little bit smaller than I expected. However as you mentioned I think it is caused by slew rate.
Is there any other recommended device?
You could try a CFA buffer like BUF602. The simulation results look promising.
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