A 55 dB range gain interpolating variable gain amplifier with improved offset cancellation

El-Shennawy, Mohammed; Joram, Niko; Ellinger, Frank

doi:10.1109/prime.2016.7519455

Cited by 10 publications

(5 citation statements)

References 4 publications

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“…The number of terms as well as the explicit form of v o (t) in (13) resulting from such an expansion being large, they are not shown here for the purpose of conciseness. However, after regrouping the output terms at the same frequency, a compact representation of the resulting v o (t) output signal and its bilateral equivalent will have the form given by (14) and (15)…”

Section: -Port Mathematical Representation a Derivation Of Equmentioning

confidence: 99%

“…Step 4: With G already known from Step 1, the V o vs. V e measurements of Step 2 and Step 3 are used in equations (12) to (15) to derive a new system of equations. The solution of this system of equations is the set of complex coefficients of the nonlinear polynomial P (p iql as defined in (11)) that relates V e with V a , and which translates into the PA's output signal V o under dynamic biasing.…”

Section: B Steps For Extracting Polynomials G and Pmentioning

confidence: 99%

“…For example, [13] improves PA linearity by using negative feedback through active elements for gain compensation when the PA's compression is significant. References [14] and [15] use negative feedback in VGA architecture to regulate the system's overall gain. Our proposed 3-port PA representation is useful for both PAs and VGAs under closed-loop operation, using either negative or positive feedback.…”

Section: Application To Closed-loop Pa With Experimental Verificmentioning

confidence: 99%

“…Examples of closed-loop systems that use dynamic feedback are not limited to PAs. References [14] and [15] are examples of gain control through closed-loop negative feedback in variable gain amplifier (VGA) implementations.…”

Section: Introductionmentioning

confidence: 99%

“…4]. Another key consideration is that the applicability of Volterra-based approach for closed-form analytical representation of closed-loop feedback systems such as [12]- [15] has not been demonstrated.…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear Three-Port Representation of PAs for Embedded Self-Calibration of Envelope-Dependent Dynamic Biasing Implementations

Sharma

Constantin

2019

IEEE Access

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This paper proposes a three-port power amplifier (PA) representation based on distinct sets of nonlinear complex polynomials that describe a combiner, a nonlinear baseband-to-RF converter and a nonlinear RF amplifying function, for processing the PA's input modulated signal and any envelope-dependent dynamic biasing signal. This novel representation of PA nonlinearities simplifies computation and renders possible analytical formulations to describe a 3-port PA system. It allows accurate prediction of the PA's output distortion components as a function of an input multi-tone excitation and a multi-tone dynamic biasing signal. The representation is intended for a context proposed, to the best of the authors' knowledge for the first time, and envisioned as promising for future mobile communication equipment-the automatic optimization of linearity performance in Radio Frequency Integrated Circuit (RFIC) PAs under any modulated excitation and employing envelope-dependent biasing, through implementation of embedded self-calibration within the transmitter front-ends. In this context, the representation introduced here compares favorably in terms of accuracy with respect to Volterra-based approaches and allows a simpler characterization, while the literature often points to the complexity inherent to Volterra-based approaches. The proposed representation allows the optimization of the PA's dynamic biasing for linearity improvement from one mobile unit to another through embedded self-calibration starting from quasi-static measurements alone of the PA's input/output power. Its applicability is highlighted through benchmarking against experimental results demonstrating accurate PA characterization for multiple PA platforms under different dynamic biasing techniques. In one implementation using an industry-designed GaAs PA, it accurately predicts the dynamic biasing adjustments to achieve more than 4dB reduction in the output intermodulation distortion (IMD 3). In another implementation using the recently introduced positive envelope feedback linearization scheme, the proposed representation allows, for the first time, analytically predicting the condition of closed-loop stability and the requirements for the feedback components with experimental verification.

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Section: -Port Mathematical Representation a Derivation Of Equmentioning

confidence: 99%