Self-calibration of input-match in RF front-end circuitry

Abstract

The input match of RF front-end circuitry can degrade significantly due to process faults and parasitic package inductances at its input pad. The proposed technique ascertains the input match frequency of the circuit by using a built-in self-test (BiST) structure, determines the frequency interval by which it needs to be shifted to restore it to the desired value, and then feeds back a digital word to the low-noise amplifier (LNA), which adaptively corrects its input-match in real-time. The circuitry presented in the paper offers the advantages of low power overheads (the circuits can be powered off when not in use), robustness, no requirements of digital signal processing cores or processors, and fast calibration times (less than 30 s). This proof of concept is demonstrated by designing a cascode LNA and the complete self-calibration circuit in IBM 0.25-m CMOS RF process.Index Terms-Built-in self-test (BiST) for RF circuits, design for fault tolerance, reliability of RF circuits, RF circuit design.

Process and Temperature Compensation for RF Low-Noise Amplifiers and Mixers

“…11). However, this variability cannot be compensated for with adaptive biasing: a self-calibration technique such as [16] is required. The last column of Table III includes the improvement that would be achieved if such a calibration technique for input matching …”

Sensitivity Analysis for Fault-analysis and Tolerance in RF Front-end Circuitry

“…By quantifying dependencies and performance degradation patterns, it can be used for optimal design of self-test and fault-tolerant systems. We have previously demonstrated successful on-chip self-calibration of LNAs in [5] [6].…”

“…The digital nature of self-calibration developed in [5] [6] is briefly summarized thus: LNA performance is sensed on-chip using novel sensors and algorithms, and downconverted to DC. The DC signals are analyzed 2 The incremental gain is computed at three different input amplitudes, with 0 being the reference and +V and -V being the other two voltages.…”

“…This information is then used to digitally modify circuit parameters, and realign circuit performance to its desired value. For example, the circuit adaptability used in [5] uses a digitally tapped inductor to dynamically change gate inductor values, and correct the input-match frequency. The SA offers guidelines on the following issues:…”

“…Self-Test solutions can be optimized by focussing on these specific patterns and ranges. The paper also discusses the application of this analysis towards self-calibration methods (we have successfully demonstrated selfcalibration of RF circuits in [5] [6]). …”