Figure 1
Fingerprint sensor cell (A) circuit for isolation scheme of sensor cell (B) implemented layout of the sensor cell.
Figure 2
Top view layout of the 25 fingerprint sensor cell array with fingerprint sensor with isolation sensor cell scheme, an evaluation sensor cell, isolation sensor cells, and transmission sensor cells.
Figure 3
The implemented fingerprint sensor with pipelin scan driver hitecture.
Figure 4
The timing diagram and output voltage characteristics of the pipelined scan driver for the fingerprint sensor.
Figure 5
The implemented full chip layout of the 96 × 96 fingerprint sensor with standard CMOS 0.25 μm technology.
Figure 6
Fabricated fingerprint sensor (A) die photo, (B) LGA package front and back.
Figure 7
Fingerprint sensor test evaluation environment.
Figure 8
PC interface program.
Figure 9
Captured fingerprint image (A) original (B) histogram equalization.
Figure 10
Wiener filtered fingerprint image (A) local size of 3 × 3, (B) local size of 5 × 5.
Figure 11
Weight of 2D Gaussian filter (A) 3 × 3, (B) 5 × 5.
Figure 12
2D Gaussian filtered fingerprint images (A) local size of 3 × 3, (B) local size of 5 × 5.
Figure 13
Weight estimation of 2D FIR filter for 50 µm-thick molded fingerprint sensor.
Figure 14
Weight of 2D FIR filter (A) 3 × 3, (B) 5 × 5.
Figure 15
2D FIR filtered fingerprint images (A) 3 × 3, (B) 5 × 5.
Figure 16
The matching performance of the fingerprint sensor (FAR vs. FRR).
Table 1
Performance summary and comparisons.
| Parameter | This work | Ref. Hassan and Kim (2018) | Ref. Shimamura et al. (2010) | Ref. Jung et al. (2005) |
|---|---|---|---|---|
| Technology | 0.25 µm | 0.13 µm | 0.5 µm | 0.35 µm |
| Type of sensor | Capacitive | Capacitive | Capacitive | Capacitive |
| Supply voltage | 1.8~2.5 V | 1.5 V | 3.3 V | 3 V |
| Molding thickness | 80 µm | – | – | – |
| Operating frequency | 10 MHz (readout 30 MHz) | 1 MHz | – | 40 MHz |
| Power dissipation | <3 mA | 7.5 mA (25 mW) | 7.5 mA (25 mW) | – |
| Image capture timea | <20 ms | 0.2 ms | 20 ms | – |
| Array size | 96 × 96 | 20 × 16 | 224 × 256 | 160 × 192 |
| Image resolution | 508 ppi | 282 ppi | 508 ppi | 423 ppi |
| FRR@FAR = 10−4 | 2.2% | – | – | – |