How can I make a 50Ω output buffer using cadence?

[test_out]

50 ohm buffer

Hi All ,


How can I make a 50Ω output buffer using cadence. I mean how can I know the output impadance of the buffer?
Please, tell me!!!

Thank you,


Test_out

 

[abcyin]

buffer 50 ohm output

Hi,

By .sp analysis, you can get what you need.

BR!

 

[test_out]

50 ohm Output buffer!

By SP ananlysis I can get only the S22 or Z22, it's not tht output impedance.(Zout)?
Am I rite?

 

[abcyin]

50 ohm Output buffer!

the Zm value is the output impedance, or you can add a AC current into the output, run ac simulation, then detect the ac voltage, it's just equal to the output impedance.

hope it helps!

 

[mba7]

50 ohm Output buffer!

i confirm,

add an ac current or an ac voltage into the output and read the voltage/current corresponding
and Zout = Vout/Iout

 

[resonator]

Re: 50 ohm Output buffer!

By SP ananlysis I can get only the S22 or Z22, it's not tht output impedance.(Zout)?
Am I rite?

For small signal, you can get the information from S22 just like an LNA.

 

[jecyhale]

Re: 50 ohm Output buffer!

Hi All ,


How can I make a 50Ω output buffer using cadence. I mean how can I know the output impadance of the buffer?
Please, tell me!!!

Thank you,


Test_out

Simualte the s22 to find if it can match the 50Ω load.

 

[lovexxnu]

50 ohm Output buffer!

why do you need output impedance ?

what you really need is S22， I think.

 

[layes2]

50 ohm Output buffer!

add RR11 netp 0 50

Added after 49 seconds:

you can also use poly res

 

[linkfox]

Re: 50 ohm Output buffer!

Hi All ,


How can I make a 50Ω output buffer using cadence. I mean how can I know the output impadance of the buffer?
Please, tell me!!!

Thank you,


Test_out

part of sample codes from my previous project, using hspice:

.ac dec 10 2g 3g
.noise v(97) vs
.net v(97) vs rin=50 rout=50
.tran 0.1ns 500ns
.print ac s11(db) s21(db) s22(db) zin(r) zin(i) zout(r) zout(i)

check the real part of zin, zout