Volterra series

About: Volterra series is a research topic. Over the lifetime, 2731 publications have been published within this topic receiving 46199 citations.

Partially decoupled Volterra filters: formulation and LMS adaptation

Abstract: The adaptation of Volterra filters by one particular method-the method of least mean squares (LMS)-while easily implemented, is complicated by the fact that upper hounds for the values of step sizes employed by a parallel update LMS scheme are difficult to obtain. In this paper, we propose a modification of the Volterra filter in which the filter weights of a given order are optimized independently of those weights of higher order. Using this approach, we then solve the minimum mean square error (MMSE) filtering problem as a series of constrained optimization problems, which produce a partially decoupled normal equation for the Volterra filter. From this normal equation, we are able to develop an adaptation routine that uses the principles of partial decoupling that is similar in form to the Volterra LMS algorithm but with important structural differences that allow a straightforward derivation of bounds on the algorithm's step sizes; these bounds can be shown to depend on the respective diagonal blocks of the Volterra autocorrelation matrix. This produces a reliable set of design guidelines that allow more rapid convergence of the lower order weight sets.

Linearization of monolithic LNAs using low-frequency low-impedance input termination

Abstract: This work investigates the linearization technique based on terminating the LNA input with low impedance at the low frequencies of the second-order mixing terms. This technique is analyzed using the Volterra series and is shown to be very effective in linearizing BJTs but not FETs if the latter are biased in the strong inversion region. Several methods to generate the low-frequency low-impedance input termination are reviewed. A SiGe BiCMOS cellular band CDMA LNA using this linearization technique is described. The LNA achieves +11.7dBm IIP3, 15.7dB gain and 1.4dB NF with a current consumption of only 3.9mA@3V.

An Improved High Linearity Active CMOS Mixer: Design and Volterra Series Analysis

Abstract: The linearity and noise requirements in multistandard applications make the design of mixers so challenging. In this paper a new highly linear CMOS mixer is proposed that utilizes second- and third-order distortion cancellation mechanisms using second harmonic injection technique, also an in-depth analysis of the mixer is presented too. The proposed circuit can work for wide channel bandwidth applications. Full Volterra series analysis of the transconductance stage of the proposed mixer is reported to show the effectiveness of the injection technique. The analysis of the mechanisms responsible for generating the fundamental tone, the second- and the third-order intermodulation distortions in the switching stage along with an LC filter is also reported. Simulations using TSMC 0.18 μm CMOS model technology demonstrate that IIP3 and IIP2 of the proposed mixer have 10 dB and 26 dB improvements in comparison with the conventional Gilbert-type mixer while the NF doesn't change significantly. The mixer achieves a conversion gain of 15 dB from a 1.8 V supply. The additional circuits used for the IM2 and IM3 cancellation mechanisms have a total current consumption of less than 1 mA.

Baseband Equivalent Volterra Series for Digital Predistortion of Dual-Band Power Amplifiers

Abstract: This paper proposes a new dual-band baseband equivalent (BBE) Volterra model devised to predict the behavior of dual-band power amplifiers (PAs) and/or to linearize their response. A series of derivations were applied to the original continuous passband Volterra-series expression to uncover a simple formulation that related the BBE envelopes of the output signals in each band to those at the input in the discrete domain. This yielded an inherently low-complexity dual-band Volterra-series model that does not require the empirical pruning commonly applied to the low-pass equivalent Volterra series. The proposed model was successfully applied to digitally predistort and linearize a dual-band 45-W class-AB GaN PA driven with different dual-band dual-standard test signals. For each band, the model necessitated less than 25 coefficients to reduce the adjacent channel leakage power ratio ACLR by up to 25 dB.