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Advanced current mirrors IS IREF M3 M1 M2 Fig.. Concept diagram of high performance current sources IREF 1 IS 3 IREF 1 IS 3 3 IREF M4 2 M3 4 M4 2 M3 1 IB IS M3 4 2 4 M4 M1 (a) M2 M1 (b) M2 M1 M2 (c) Fig.. Standard high performance current sources (a) Wilson type, (b) cascode type, and (c) active feedback type 1 IREF + - IMA X IS M4 M3 M1 M2 M5 IREF IS M4 M3 M1 M2 VREF (a) (b) Fig. Cascode current sources with reference voltage (a) the concept and (b) an implementation. IREF I*REF IREF 1 M4 8 IS VDD IS M7 3 M3 M4 M8 M3 2 4 M5 0.25W/L (a) M1 M2 M2 M1 M6 M5 0.25W/L (b) Fig. Modification of the current source of Fig. 3(b) with dynamic range adjustment: (a) circuit controlled by two identical reference currents and (b) circuit with auxiliary current mirrors.(All unmarked transistors have the same W/L=5 ratios) 2 IREF 1 VDD IREF 1 M4 4W/L IS 6 VDD VREF 6 M6 IS 4W/L 3 3 M6 M4 2 M3 M7 8 M3 8 7 4 M5 M1 4 M5 2 M2 M1 M2 (b) (a) Fig.. Choi at al. circuits [2]: (a) original circuit and (b) modified circuit for low output voltage operation. (All unmarked transistors have the same W/L=5 ratios) IREF 1 M6 IREF VX M5 M5 W/3L IS 7 IS 3 M4 M3 M3 M4 6 M1 M2 4 M1 2 M2 (a) (b) Fig. Bruun and Shah circuits (a) concept circuit and (b) actual circuit for low output voltage operation. (All unmarked transistors have the same W/L=5 ratios) 3 IREF IS VR IREF 8 IS 1 3 M5 IS 1 +V DD IREF M5 7 3 M3 M4 M4 M3 M4 M3 2 4 6 M2 M1 M1 (b) (a) M2 + - Vb 4 2 M1 M2 (c) Fig. CMOS current mirrors: (a) simple CMOS mirror, (b) high quality CMOS current mirror and (c) gate of M5 transistor was connected to additional biasing voltage Vb for testing purposes. In actual implementation Vb is zero. IREF IS M6 M5 M7 M4 M1 M2 M3 Super high output resistance 4 IREF IS M4 M6 M5 M2 M1 M3 All transistors the same W/L except M4 where W/L4=0.25W/L W4=0.25W Low voltage high quality current mirror IREF IBIAS IS 1 5 M3 M4 6 3 M7 M5 M6 VREF 4 M1 M2 2 E:\spfiles\cursrc1.cir 5 Bi-directional current mirrors VDD M4 M6 IIN IBIAS IOUT M1 M5 M1 Fig @@ Bidirectional current mirror VDD M4 IIN M6 M3 VREF1 M2 VREF2 M1 IOUT M5 Bi-directional current inverter/amplifier 6 Current multipliers and dividers (by fixed ratio) VREF IREF IREF IS M3 M5 0.25W/L M1 M2 (a) 7
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