Characteristics of LNA Operation in Direct Delta–Sigma Receivers

Author

Ostman, Kim B. ; Englund, Mikko ; Viitala, Olli ; Stadius, Kari ; Koli, Kimmo ; Ryynanen, Jussi

Author_Institution

Dept. of Micro & Nanosci., Aalto Univ., Aalto, Finland

Volume

61

Issue

2

fYear

2014

fDate

Feb. 2014

Firstpage

70

Lastpage

74

Abstract

This brief analyzes the dual role and operation of the low noise amplifier (LNA) in the recently introduced direct delta-sigma receiver (DDSR). First, the LNA functions as a transconductor in an integrator stage, and in this role, we explore the effects of LNA output impedance on quantization noise shaping by the system. In the second role of a voltage preamplifier, we show how the closed-loop DDSR structure impacts LNA voltage gain and system noise. LNA and system properties are thus intertwined and lead to the need for careful codesign. The reliability of the utilized continuous-time DDSR approximation is verified by simulating a sample receiver model.

Keywords

delta-sigma modulation; low noise amplifiers; operational amplifiers; preamplifiers; radio receivers; reliability; LNA operation characteristics; LNA output impedance; LNA voltage gain; closed-loop DDSR structure; continuous-time DDSR approximation; direct delta-sigma receivers; integrator stage; low noise amplifier; quantization noise shaping; reliability; sample receiver model; system noise; transconductor; voltage preamplifier; Gain; Impedance; Modulation; Noise; Noise shaping; Radio frequency; Receivers; Circuit optimization; delta–sigma ($ DeltaSigma$) modulation; direct delta–sigma receiver (DDSR); noise; radio-frequency (RF) amplifiers; receivers;

fLanguage

English

Journal_Title

Circuits and Systems II: Express Briefs, IEEE Transactions on

Publisher

ieee

ISSN

1549-7747

Type

jour

DOI

10.1109/TCSII.2013.2291092

Filename

6683063