文档介绍：614 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—II: ANALOG AND DIGITAL SIGNAL PROCESSING, VOL. 48, NO. 6, JUNE 2001
Transactions Briefs__________________________________________________________________
A CMOS Fully Balanced Differential Difference Amplifier II. DESIGN TRADEOFFS
and Its Applications The DDA is a five-terminal device as shown in Fig. 1(a). It has two
differential input ports, @ pp – pn A and @ np – nn A rather than two
Hussain Alzaher and Mohammed Ismail
single-ended inputs, as is the case in the conventional op-amp. The
output of the DDA can be expressed as
Abstract—This brief presents the fully balanced version of the differ-
ential difference amplifier (DDA) as an essential building block for imple- o a e o @ pp
pn A
@ np
nn A (1)
menting fully differential architectures of analog CMOS integrated circuits
(ICs). We demonstrate that the fully balanced differential difference ampli-
fier (FBDDA) provides the solution for systematically developing fully dif- where e o is the open-loop gain of the DDA. Analogous to the tra-
ferential versions of any single-ended op-amp based circuit. We also show ditional op-amp, when a negative feedback is applied, the differential
that, unlike the DDA, the FBDDA exhibits a wide input range without de- voltages of the two input ports e equal
plex circuitry. A low-power class AB CMOS realiza