A -78dB THD 100 /spl Omega/ Differential Driver For ISDN Applications

A key circuit in mixed analog/digital CM OS systems is an off-chip buffer capable of driving low-resistive and/or high-capacitive loads. For example, the line driver of a U-Interface chip must drive a resistive load ranging from 50Q to a few hundred and up to a few hundred pF in a differential configuration.1.2 The key requirement is linearity of 70dB or more for a 6Vpp differential output swing on a 5V supply with a signal frequency in the 40kHz to 80kHz range. Low power consumption and small area are also important. In general, however, there is a trade-off between linearity on one hand and power consumption and silicon area on the other hand.