Area-efficient high-voltage switch using floating control ... - IEEE Xplore

Area-efficient high-voltage switch using floating control circuit for 3D ultrasound imaging systems Sung-Jin Jung, Seong-Kwan Hong and Oh-Kyong Kwon A high-voltage (HV) switch is proposed which adopts the floating control circuit to reduce area by removing the passive components and reducing the number of laterally diffused metal–oxide semiconductor field effects (LDMOSFETs). The proposed HV switch consists of three LDMOSFETs and three MOSFETs without any passive components. In addition, the routing complexity of the control signals is greatly reduced by sharing all control signals in the array of switches. The proposed HV switch is fabricated using a 0.18 μm CMOS process with 50 V devices and occupies 85 × 65 μm2. The measured off-isolation is −53 dB.

and source of HN1 and HN2 are discharged to the lowest voltage (−25 V). The HV switch is turned on by the charging gate and source of HN1 and HN2 to 1.8 V and 0 V, respectively. Accordingly, the voltage swings of the gate and source of HN1 and HN2 become −25–1.8 V and −25–0 V, respectively. Since VGS.MAX of n-channel LDMOSFET is only 1.8 V, VGS of HN1 and HN2 should be carefully controlled to protect the gate oxide of HN1 and HN2 during turn-on and turn-off operations of the HV switch. The proposed FCC reliably controls VGS of HN1 and HN2 using only one LDMOSFET, three LV MOSFETs, and four control signals (EN1–EN4). The FCC consists of an n-channel LDMOSFET (HN3) and three MOSFETs (LN1, LN2, and LP1) with control signals. HN3 discharges the source and body of HN1 and HN2 to −25 V, and LN1 and LP1 keep VGS of HN1 and HN2