**Appendix A. Body-to-Gate (B2G) Interface**

This section aims to explain the body-to-gate (B2G) interface which is exploited in each stage *i*th−1, *i*th interface. Following the notation in Figure A1a, the current gain can be expressed as:

$$\frac{I\_{out}}{I\_{in}} = \frac{\mathcal{g}\_{m\_B}}{\mathcal{g}\_{mb\_A}} \left( \frac{1}{1 + \frac{1}{\mathcal{g}\_{mb\_A}\sqrt{\mathcal{g}\_{ds\_A}}}} \right) \frac{1}{1 + s\frac{\mathcal{C}\_{\mathcal{S}^o\_B} + \mathcal{C}\_{\mathcal{b}^o\_A} + \mathcal{C}\_{\mathcal{g}^d\_A} + \mathcal{C}\_{\mathcal{g}^d\_B}\chi\_a}} \tag{A1}$$

where *χα* derives from Miller approximation on *CgdB* and can be therefore expressed as:

$$\chi\_{\mathfrak{a}} = \frac{\mathcal{g}\_{m\_{\mathfrak{B}}}}{(\mathcal{g}\_{ds\_{\mathfrak{B}}} + \mathcal{g}\_{load})} \tag{A2}$$

where *gload* load conductance and as a consequence it could be equal to *gmbload* or *gdsload* (respectively, for stage1,2 and stage3). It is possible thereafter to conclude that the interface behaves as a small signal current-mirror with gain.

**Figure A1.** (**a**) Body-to-gate (B2G) interface; (**b**) body-to-body (B2B) mirror.
