A modular programmable and linear charge pump with low current mismatch

Abstract

In this work, a new Charge Pump (CP) design including a Phase and Frequency Detector (PFD) is presented. The PFD is designed using the common topology of two D Flip Flops, AND gates and a controllable reset delay for the DFFs to compensate for process and tem-perature variations. The Charge Pump is using a bias cell which generates the necessary bias voltages, the clock driving cells which convert the single-ended UP and DOWN signals to differential and the core cell which comprises of six slices, each one contributing the same amount of current to the low pass filter. The output current is programmable with minimum and maximum values of 25 uA and 150 uA respectively. An extra option to double the output current is also added. A new technique has been adopted in terms of layout floorplan of the charge pump slices to eliminate the clock feedthrough mismatch between the differential UP and DOWN sig-nals. The technology used in this work is TSMC 65nm, while the supply voltage is 1 V. The main characteristics of the proposed design are modularity, low power, low noise, great linearity, small area, simplicity and performance.