## 2 Proposed TSP Readout System
### Sensing Front-End  
Figure 3 illustrates the sensing front-end, consisting of a CCII and a C2V converter along with its timing diagram. The CCII, directly connected to the TSP electrode via SWCHG, has its X node (V\({}_{\rm X}\)) referenced to the Y node voltage (V\({}_{\rm Y}\)). When V\({}_{\rm Y}\) is driven by an AC-modulated VDRV, V\({}_{\rm X}\) achieves the same voltage level and drives C\({}_{\rm S}\)[n] with virtual V\({}_{\rm DBV}\). The V\({}_{\rm DBV}\) signal is generated by a unity-gain buffer and a resistor string in the reference generator, where V\({}_{\rm H}\) and V\({}_{\rm L}\) are alternately selected by VDRV,CTR to produce the AC-modulated VDRV. Another key feature of the CCII is its ability to copy the input current (I\({}_{\rm X}\)) to the Z node (I\({}_{\rm Z}\)) with a multiplication factor of K. Since C\({}_{\rm S}\)[n] is driven by the virtual V\({}_{\rm DBV}\), a proportional charge of V\({}_{\rm DBV}\)\(\times\) C\({}_{\rm S}\)[n] is generated and transferred to the X node as a current. However, due to the large C\({}_{\rm S}\)[n] of the TSP electrode, the I\({}_{\rm Z}\) (=K \(\times\) I\({}_{\rm X}\)) can saturate the subsequent front-end stage. To mitigate this, only the capacitive variation from C\({}_{\rm S}\)[n], approximately corresponding to the C\({}_{\rm F}\) of a finger, should be transferred to the next sensing stage. For this purpose, a dot-matrix C\({}_{\rm S}\)-compensator is designed, with its output connected to C\({}_{\rm S}\)[n]. Instead of fully transferring the charge of V\({}_{\rm DBV}\)\(\times\) C\({}_{\rm S}\)[n], the static portion of C\({}_{\rm S}\)[n] is eliminated by Q\({}_{\rm C}\)[p]. Since the charge of V\({}_{\rm DBV}\)\(\times\) C\({}_{\rm S}\)[n] is modulated by f\({}_{\rm TSP}\), the proposed compensator alternately generates sinking (QS\({}_{\rm K,O}\)) and sourcing (QS\({}_{\rm C,O}\)) charges for effective compensation. Once the sampling switch (SWCHG) is closed, only the differential charge of \(\Delta\)Q (=V\({}_{\rm DBV}\)\(\times\) C\({}_{\rm S}\)[n] - Q\({}_{\rm C,PO}\)) is transferred. The charge of Q\({}_{\rm C,DREF}\) is generated by a metal-insulator-metal (MIM) reference capacitor (C\({}_{\rm REF}\)) driven by virtual V\({}_{\rm DBV}\), while a current amplifier at the output boosts that current to Q\({}_{\rm C,PO}\) through fine and coarse tuning. The tuning ratio (M) can be reconfigured depending on the measurable channel-dependent size of C\({}_{\rm S}\)[n]. Figure 2: Proposed dot-matrix TSP analog front-end (AFE) architecture with frequency range of TSP signal and noise across the LCD display. To mitigate external noises, such as V\({}_{\text{COM}}\) noise, the sensing front-end incorporates a bandpass filter (BPF). The charge conversion from C\({}_{\text{S}}\)[n] to I\({}_{\text{X}}\) at the CCII input generates a transfer function's zero at DC. Conversely, the large parasitic capacitance combined with the input impedance of the CCII forms a high-frequency low-pass pole. The C2V converts this high-pass-filtered I\({}_{\text{Z}}\) to a proportional voltage. Simultaneously, R\({}_{\text{INT}}\) in parallel with C\({}_{\text{INT}}\) introduces a low-frequency high-pass pole, collectively shaping the bandpass filter response. The passband gain (A\({}_{\text{V}}\)) from V\({}_{\text{DRV}}\) to V\({}_{\text{C2V}}\) can be described by  
\[\text{A}_{\text{V}}=\frac{\text{K}(\text{C}_{\text{S}}[n]-\text{M}\times\text {C}_{\text{REF}})}{\text{C}_{\text{INT}}} \tag{1}\]  
where K is the current gain of CCII from the X node to the Z node, and M denotes the charge-boosting ratio of the dot-matrix C\({}_{\text{S}}\)-compensator, which can be reconfigured based on the size of C\({}_{\text{S}}\)[n].