A fully differential op amp with mismatch is connected in the feedback circuit in Fig. 12.32a With R₁= R₂=10 kΩ and R₃= R₄= 40 kΩ. The op amp model is shown in Fig. 12.37 where a_dm= ˆ’181, a_cm= ˆ’2.89, a_cmc= ˆ’226, a_{dm ˆ’ cm}= 8.95, a_cmˆ’dm = 0.15, and a_cmcˆ’dm = 11.6. If the gain of the CMFB circuit is a_cms= 0.76, find the closed- loop gains A_dm= v_od/v_sd, A_cm= v_oc/v_sc, A_dmˆ’cm= v_oc/v_sd, and A_cmˆ’dm= v_od/v_sc.

Fig. 12.32 (a):

Fig. 12.37:

R3 R1 V od V d R2 R4 (a) Vo1 Vi1 Vo2 Vi2 V emc Vo1 Vid a 2 Vic -d Vi1 V eme a cmc-dm 2 Vi2 - 2 Vic Vie a cm-dm a dm-cmVid Vid a 2 AcmcVem Vo2