cmos集成电路设计2资料.ppt

Beijing Institute of Technology, China Prof. Y. HU 1 December, 2006 Current-Mode Analog Signal Processing ? Current-mode circuit techniques is an alternative to conventional and switched capacitor circuits for continuous and sampled-data analog signal-processing systems. Beijing Institute of Technology, China Prof. Y. HU 2 December, 2006 Why Current-Mode? ? Low-voltage makes it difficult to design voltage- mode circuits with high linearity and wide dynamic range ? Current-mode circuits can operate with low power- supply voltages because of the small voltage swings associated with the low impedance nodes. ? Current-mode meets the requirements of high- frequency and high-accuracy circuits. ? Current-mode is patible with digital systems. ? Low noise logic used in design of mixed-signal ICs Beijing Institute of Technology, China Prof. Y. HU 3 December, parison between V-M and C-M ? Voltage mode: ? High input impedance ? Low output impedance ? Current mode: ? Low input impedance ? High output impedance Beijing Institute of Technology, China Prof. Y. HU 4 December, 2006 Basic Current-mode Circuits ? Transfer function: ? It can perform 3 of the four basic processing operations ? Invert ? Scale (amplification) ? add M 1M 2 I RkI RI O UT (W/L) k(W/L) I in 1 I in 2)II(kI 2 in1 in OUT??? Beijing Institute of Technology, China Prof. Y. HU 5 December, 2006 Basic Switched-Current Circuits ? The fourth basic signal processing operation is delay. ? Switched-current circuit: (Track-and-hold) ? With M S" on " the circuit tracks the I in: ? With MS turned " off " the circuit holds the I OUT current on the M S gate. The circuit has a current memory. )II(kI 2 in1 in OUT??? M 1M 2 I RkI RI O UT (W/L) k(W/L) I in 1 I in 2M S Clock Beijing Institute of Technology, China Prof. Y. HU 6 December, 2006 Current Conveyors (CCI) (1) ? First generation current conveyor: ?i