Name
Title | ||
|---|---|---|
A 4.5 GΩ-Input Impedance Chopper Amplifier With Embedded DC-Servo and Ripple Reduction Loops for Impedance Boosting to Sub-Hz |
Abstract | ||
|---|---|---|
Achieving a high input impedance Z
<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in</sub>
is important for the instrumentation amplifier (IA) performing neural and biopotential signal sensing. Previously, impedance boosting techniques have been used with a positive feedback loop (PFL) driven by the output or auxiliary (AUX) path driven by the input. We propose that the conventional approach to DC-servo loop (DSL), which blocks the electrode offset (EOS), does not fully enable the function of a PFL or AUX path. This results in either limited impedance boosting or reduction of a low-frequency Z
<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in</sub>
in the sub-Hz band. To solve this problem and achieve Z
<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in</sub>
boosting down to sub-Hz, we propose a new approach to DSL for a capacitively-coupled chopper instrumentation amplifier (CCIA). The proposed DSL is realized using a 30-nA opamp, and the AUX path is designed using a 450-nA duty-cycled buffer. The CCIA achieves a gain of 40 dB and is implemented using a 0.18 μm CMOS process with an area of 0.19 mm
<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>
. The measured results show that Z
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is increased by 184 times up to 4.6 GQ at 0.01 Hz. Compared to the CCIA using conventional DSL, Z
<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in</sub>
is improved by 7.8 times. An input-referred noise of 2.1 μVrms is achieved at 2.14 μW. |
Year | DOI | Venue |
|---|---|---|
2021 | 10.1109/TCSII.2020.3007934 | IEEE Transactions on Circuits and Systems II: Express Briefs |
Keywords | DocType | Volume |
Instrumentation amplifier,neural sensing,chopping,input impedance,dc servo loop,input-referred noise | Journal | 68 |
Issue | ISSN | Citations |
1 | 1549-7747 | 0 |
PageRank | References | Authors |
0.34 | 0 | 5 |
Name | Order | Citations | PageRank |
|---|---|---|---|
| Xuan Thanh Pham | 1 | 0 | 1.35 |
| Duc Nha Duong | 2 | 0 | 0.34 |
| Ngoc Tan Nguyen | 3 | 0 | 0.34 |
| Van Truong Nguyen | 4 | 0 | 0.34 |
| Jong-Wook Lee | 5 | 66 | 11.45 |