Why is the bandwith of a current conveyor larger than opamp?

[matrixon]

why the bandwith of current conveyor is larger than opamp?

I heard that the bandwidth of a current conveyor is higner than opamp because it work at open loop.I don't understand what's the reason.

The open loop 3dB BW of an opamp is 1/RoCo,where Ro and Co is the res and cap at the output node and the BW is wider in closed loop operation.
why a current conveyor has larger BW at open loop condition?

 

[dick_freebird]

Re: why the bandwith of current conveyor is larger than opamp?

1/RoCo is not the op amp bandwidth unless the load is
dominant. Not a good way to bet. Often the BW is set by
internal compensation in unity-gain stable or "gain of X
stable" op amps.

Because voltage mode op amps want high stage gain and
low power, Ro is made high and current made low (Ro is
maximized at low current, and low current is also a competitive
feature). But node capacitance is not so easily driven down,
and internal slew rates then are your sum critical node
capacitance and your available current to swing that node,
dV/dt=I/C. dV/dt at small signal going directly to bandwidth.

Current conveyors (current mirror cascades) may be built
with lower stage gains, and their construction makes them
low impedance so stage RC corners are high frequency. No
high impedance nodes, no long time constants.

 

[matrixon]

Re: why the bandwith of current conveyor is larger than opamp?

Current conveyors (current mirror cascades) may be built
with lower stage gains, and their construction makes them
low impedance so stage RC corners are high frequency. No
high impedgnance nodes, no long time constants.

but in the image,the z node has impedance as hign as opamp