Low Power and Area Efficient Phase Accumulator for DDFS Applications

This paper presents a low power and area efficient ‘phase accumulator’ (PACC) with 32-bits frequency resolution and 10-bits phase resolution. The PACC is derived based on primitive phase accumulator architecture, using a novel "hybrid carry propagate adder" (HCPA). The HCPA consists 8 "full adder" (FA) cells in its carry propagate chain. Out of 8 FA cells, the "most significant bit (MSB)-FA" (MFA) cell uses 28-transistors and each of the remaining 7 "least significant bit (LSB)-FA" (LFA) cells uses 16-transistors. This hybrid combination of MFA with LFA cells provide both low transistor count as well as low power dissipation benefits. The proposed PACC has a maximum frequency of operation (fmax) =410 MHz, consumes an average power dissipation of 80.56 µWatts at supply (Vdd) =1.2 V and has a total "transistor count" (TC)=2096. All the circuit simulations are carried out using Cadence’s Spectre simulator based on 90 nm technology node.