Multiple output CMOS current amplifier

Abstract

Abstract. In this paper the multiple output current amplifier basic cell is proposed. The triple output current mirror and current follower circuit are described in detail. The cell consists of a split nMOS differential pair and accompanying biasing current sources. It is suitable for low voltage operation and exhibits highly linear DC response. Through cell devices scaling, not only unity, but also any current gains are achievable. As examples, a current amplifier and bandpass biquad section designed in CMOS TSMC 90nm technology are presented. The current amplifier is powered from a 1.2V supply. MOS transistors scaling was chosen to obtain output gains equal to -2, 1 and 2. Simulated real gains are -1.941, 0.966 and 1.932 respectively. The 3dB passband obtained is above 20MHz, while current consumption is independent of input and output currents and is only 7.77µA. The bandpass biquad section utilises the previously presented amplifier, two capacitors and one resistor, and has a Q factor equal to 4 and pole frequency equal to 100 kHz.Key words: current amplifier, current follower, current mirror, CMOS technology. Multiple output CMOS current amplifier Core of current amplifier circuitProposed current mirror/follower is based on nMOS differential pair and is presented in Fig. 1

Programmable Input Mode Instrumentation Amplifier Using Multiple Output Current Conveyors

“…2. It consists of an operational amplifier (OA) and − as the output stage − a current amplifier described in [11]. Due to the negative feedback loop in the signal path (which starts at X terminal and then passes through OA and an inverting MN1 device), voltages at Y and X terminals should be of the same value.…”

“…That is why any current flowing to the X terminal is also amplified and moved to output terminals ZP, ZPM1, and ZM2. It should be noted that − according to the current amplifier concept in [11] − if all MN1 − MN4 devices have identical dimensions, then, ideally, neglecting resistances of bias current sources IBIAS and 4IBIAS, the current gains to output terminals ZP, ZPM1, and ZM2 are equal to −1, 1 and 1, respectively. In a real circuit, which employs cascoded MOS current sources, the absolute values of those current gains are very close but not exactly equal to 1.…”

“…In a real circuit, which employs cascoded MOS current sources, the absolute values of those current gains are very close but not exactly equal to 1. It is also worth noticing that, according to the circuit in [11], the current gains to all outputs have similar frequency responses.…”

“…In this paper a new concept of multiple output second order current conveyor (MOCCII) is presented (Section 2). It uses, as the output stage, a current amplifier reported in [11]. Then MOCCII is used as the main active block of a programmable input mode instrumentation amplifier (Sections 3 and 4).…”