The paper presents a high-voltage integrated-circuit driver capable of producing analog voltages up to 300 V, using Dalsa's 0.8-mu m HV CMOS/DMOS process, suitable for MEMS and medical systems. The IC driver includes a HV operational amplifier (op-amp) with a class-B output stage, and HV analog switches with improved off-isolation performance. In contrast to previous frequency compensation schemes, where only one dominant pole occurs below the unity-gain bandwidth, the HV op-amp employs a novel frequency compensation topology with three poles and two zeros located within the unity-gain bandwidth, and is capable of driving large capacitive loads from 100 pF to 10 nF. Theoretical analysis of off-isolation of the HV analog switches is also reported and confirms the improvement in off-isolation performance.