doubt in 2 stage opamp desgin

[satyanitt]

im designing opamp wid gain > 50db UGB= 100Mhz
im going for two stage opamp...
first one is telescopic pmos input
second one is AB class ...
my slew rate is 25v/us
wid that slew rate im able to arive I bias to 100 uA at the output stage
bt im confused wat bias current shud i take for first stage....
any relation b/w the currents of first stage n second stage?
thank u

 

[ninju]

whats the required swing at the output?

 

[satyanitt]

1.5 to 0.2... if i wer to use simple cs amplifier as second stage explain me plzzzz

 

[ninju]

You haven't given enough parameters. Whats the expected load capacitance at the output?

There is a relation between the two stage currents. It does depend on the slew rate. The output stage current should support a slew rate greater than or equal to the specified slew rate while driving the compensation capactior and the load capacitor.

The first stage current should be able to support the slew rate with the compensation capacitor alone.

Please post some diagram and all the given parameters.

 

[satyanitt]

my load capacitance is 4 pF... can u tell me hw current the relation goes?...im concerned abt swing so i put a cs stage as second stage
and for gain i put pmos input telescopic ....bothh Cc and Cl are 4 pF

 

[ninju]

your slew rate is 25V/us. so, I in the outer stage must support I/(Cl+Cc) = 25V/us. Any power spec. given? Also tell supply voltage. Gotta see how much total current is available. Also, how much current does the reference current generator require?