{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

240ln08 - COMPONENT MISMATCH IN DIFFERENTIAL...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 COMPONENT MISMATCH IN DIFFERENTIAL AMPLIFIERS LN #8 (Pages 231 – 246 in the text) I os 2 V os - + IDEAL BALANCED DIFFERENTIAL AMPLIFIER INPUT OFFSET VOLTAGE V os INPUT OFFSET CURRENT I os For an emitter coupled DA 2 1 2 1 2 1 ln s s c c T BE BE ID I I I I V V V V = = The definition of V os is value of V ID for zero output I c1 R 1 = I c2 R 2 1 2 2 1 c c c c R R I I = Then = ) ( ) ( ln 2 1 1 2 1 2 VCB Q VCB Q A A R R V V B B c c T os I s =(qn i 2 D n /Q B (V CB ))A Using perturbation and the approximation ln (1+x) x , we have + B B c c T os Q Q A A R R V V Note the dependence on temperature T Vos dT dVos = By definition the offset current is 0 2 1 2 1 = > −− > −− = od B B c c os V when I I I I I β β MOS SOURCE COUPLED PAIR Ios 0 by definition 2 2 1 1 2 1 2 1 ) / ( ' 2 ) / ( ' 2 L W k I L W k I V V V V V D D t t GS GS id + = = for 0 2 2 1 1 = = D D D D od R I R I V
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon