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A 6‐bit 4 MS/s 26fJ/conversion‐step segmented SAR ADC with reduced switching energy for BLE
Author(s) -
Samadpoor Rikan Behnam,
Abbasizadeh Hamed,
Cho SungHun,
Kim SangYun,
Ali Imran,
Kim SungJin,
Lee DongSoo,
Pu YoungGun,
Lee MinJae,
Hwang KeumCheol,
Yang Youngoo,
Lee KangYoon
Publication year - 2018
Publication title -
international journal of circuit theory and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.364
H-Index - 52
eISSN - 1097-007X
pISSN - 0098-9886
DOI - 10.1002/cta.2388
Subject(s) - effective number of bits , spurious free dynamic range , successive approximation adc , capacitor , electronic engineering , computer science , electrical engineering , cmos , comparator , nyquist frequency , converters , voltage , engineering , filter (signal processing)
Summary This paper presents a 6‐bit 4 MS/s segmented successive approximation register analog‐to‐digital converter for Bluetooth low energy transceiver applications. To improve the linearity and reduce the switching power consumption, a segmented structure with new switching scheme is adopted in the capacitive digital‐to‐analog converter. The proposed switching sequence determines the MSBs according to the thermometer codes and skips some of the unnecessary steps while avoiding bubble errors. To ensure the common mode voltage remains comparatively steady, and to avoid employing power‐hungry common mode reference voltage circuits, each capacitor is divided into 2 identical small capacitors, connecting one of them to “high” and the other one to “low”. The switching sequence is straightforward, and a split capacitor with an integer value is applied, which almost halves the total number of capacitors while retaining the unit capacitor value intact. The prototype analog‐to‐digital converter is fabricated and measured in a 55‐nm (shrinked 65 nm) complementary metal‐oxide semiconductor process and achieves 5.48 to 5.92 Effective Number of Bits (ENOB) at a sampling frequency of 4 MS/s. The Signal to Noise and Distortion Ratio (SNDR) and Spurious Free Dynamic Range (SFDR) for Nyquist input frequency are 34.79 and 40.03 dB, respectively. The current consumption is 4.8 μA from a 1.0‐V supply, which corresponds to the figure of merit of 26 fJ/conversion‐step. The total active area of the analog‐to‐digital converters for the I and Q paths of the receiver is 105 μm × 140 μm.