Simple low-voltage high-speed high-linearity V-I converter with S/H for analog signal processing applications

This paper presents a simple, high-speed, high-linearity V-I converter that has a sample/hold (S/H) function and can be operated under low voltage supply. The converter can be used as the “front end” of current-mode signal processors. The proposed V-I converter circuit is comprised of a current copier and a small resistor that can be realized on chip by using polysilicon. The current copier employed in this implementation has a very small input impedance (≅50 Ω) and is settled within 0.1% in 15 ns under a power supply of 3.3 V. The high-linearity V-I conversion is achieved by using a small resistor (2 kΩ). Simulation results show that, with the transistor parameters of MOSIS 2 μm CMOS technology, the converter achieves a small low-frequency THD (<-65 dB) at a sample rate of 25 MSamples/s, and consumes about 2.5 mW under a power supply of 3.3 V