Synthesis of a wireless communication analog back-end based on a mismatch-aware symbolic approach

In this paper, a methodology to automate the synthesis of an industrial-purpose analog integrated circuit, namely the back-end of an I&Q transmit interface, is presented. A good matching between both I and Q channels is desirable to ensure the correct circuit functioning. The proposed methodology combines the use of symbolic expressions with numerical approaches. While the symbolic expressions allow a fast iterative evaluation of the circuit performance, the numerical capabilities ensure a rapid optimization of the results. Unlike other approaches, the methodology uses symbolic expressions explicitly considering device mismatch, which are evaluated performing a Monte-Carlo analysis. The expressions have been obtained using an error-control process guided by the mean and standard deviation values of the circuit performance characteristics. This provides two benefits. First, smaller expressions are obtained. Second, expression evaluation is faster: smaller number of operations - symbol products and term sums - are carried out since, at each Monte-Carlo run, only those symbols related to device mismatch are to be changed, while the rest remains constant. A comparison between the presented synthesis technique and other purely numerical and numerical/symbolic approaches is also given.